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1.
  • Ahmed, Hesham, et al. (author)
  • Effect of carbon concentration and carbon bonding type on the melting characteristics of hydrogen- reduced iron ore pellets
  • 2022
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 21, s. 1760-1769
  • Journal article (peer-reviewed)abstract
    • Decarbonization of the steel industry is one of the pathways towards a fossil-fuel-free environment. The steel industry is one of the top contributors to greenhouse gas emissions. Most of these emissions are directly linked to the use of a fossil-fuel-based reductant. Replacing the fossil-based reductant with green H2 enables the transition towards a fossil-free steel industry. The carbon-free iron produced will cause the refining and steelmaking operations to have a starting point far from today's operations. In addition to carbon being an alloying element in steel production, carbon addition controls the melting characteristics of the reduced iron. In the present study, the effect of carbon content and form (cementite/graphite) in hydrogen-reduced iron ore pellets on their melting characteristics was examined by means of a differential thermal analyser and optical dilatometer. Carburized samples with a carbon content 2 wt%, the molten fraction is higher in the case of carburized samples, which is indicated by the amount of absorbed melting heat.
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2.
  • Almessiere, M. A., et al. (author)
  • Effects of Ce-Dy rare earths co-doping on various features of Ni-Co spinel ferrite microspheres prepared via hydrothermal approach
  • 2021
  • In: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854 .- 2214-0697. ; 14, s. 2534-2553
  • Journal article (peer-reviewed)abstract
    • The effects of Ce-Dy co-doping on the crystal structure, optical, dielectric, magnetic properties, and hyperfine interactions of Ni-Co spinel ferrite microspheres synthesized hydrothermally have been studied. A series of ferrites with the general formula Ni0.5-Co0.5CexDyxFe2-2xO4 were synthesized with x values ranging from 0.00 to 0.10. The phase, crystallinity, and morphology of ferrite microspheres were analyzed by X-ray powder diffractometry (XRD), scanning and transmission electron microscopes (SEM and TEM), respectively. The structural analyses of the synthesized ferrite microspheres confirmed their high purity and cubic crystalline phase. The Diffuse reflectance spectroscopic (DRS) measurements were presented to calculate direct optical energy band gaps (E-g) and is found in the range 1.63 eV - 1.84 eV. Fe-57 Mossbauer spectroscopy showed that the hyperfine magnetic field of tetrahedral (A) and octahedral (B) sites decreased with the substitution of Dy3+-Ce3+ ions that preferrentially occupy the B site. The impact of the rare-earth content (x) on the magnetic features of the prepared NiCo ferrite microspheres was investigated by analyzing M-H loops, which showed soft ferrimagnetism. The magnetic features illustrate a great impact of the incorporation of Ce3+-Dy3+ ions within the NiCo ferrite structure. The saturation magnetization (M-s), remanence (M-r), and coercivity (H-c) increased gradually with increasing Ce-Dy content. At x = 0.04, M-s, M-r, and H-c attain maximum values of about 31.2 emu/g, 11.5 emu/g, and 512.4 Oe, respectively. The Bohr magneton (n(B)) and magneto-crystalline anisotropy constant (K-eff) were also determined and evaluated with correlation to other magnetic parameters. Further increase in Ce3+-Dy3+ content (i.e., x >= 0.06) was found to decrease M-s, M-r, and H-c values. The variations in magnetic parameters (M-s, M-r, and H-c) were largely caused by the surface spins effect, the variations in crystallite/particle size, the distribution of magnetic ions into the different sublattices, the evolutions of magneto-crystalline anisotropy, and the variations in the magnetic moment (n(B)). The squareness ratios were found to be lower than the predicted theoretical value of 0.5 for various samples, indicating that the prepared Ce-Dy substituted NiCo ferrite microspheres are composed of NPs with single-magnetic domain (SMD). Temperature and frequency-dependent electrical and dielectric measurements have been done to estimate the ac/dc conductivity, dielectric constant, and tangent loss values for all the samples. The ac conductivity measurements confirmed the power-law rules, largely dependent on Ce-Dy content. Impedance analysis stated that the conduction mechanisms in all samples are mainly due to the grains-grain boundaries. The dielectric constant of NiCo ferrite microspheres give rise to normal dielectric distribution, with the frequency depending strongly on the Ce-Dy content. The observed variation in tangential loss with frequency can be attributed to the conduction mechanism in ferrites, like Koop's phenomenological model.
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3.
  • Arafa, Salaheddin, et al. (author)
  • Investigation into the permeability and strength of pervious geopolymer concrete containing coated biomass aggregate material
  • 2021
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 15, s. 2075-2087
  • Journal article (peer-reviewed)abstract
    • Waste palm oil products can be recycled in the production of pervious geopolymer concrete (PGC) for long-term sustainable development. PGC is a non-slip porous pavement concrete that allows water to pass through. Biomass aggregate (BA) is produced by burning palm oil biomass and is introduced as a replacement for natural aggregate (NA). BA is mixed with fly ash (FA) and alkaline liquid (AL) and heated in an oven at 80 °C for 24 h to produce coated biomass aggregate (CBA). PGC containing CBA is commonly used as a cement substitute in concrete. This study aims to develop and evaluate the effect of rainfall intensity on the ability of PGC to reduce stormwater runoff. Coating BA with geopolymer paste resulted in improved properties, better Aggregate crushing value (ACV), Aggregate impact value (AIV), water absorption and higher compressive strength compared with BA. Results indicated, a PGC with a FA/CBA ratio of 1:7, CBA of 5–10 mm, NaOH molarity of 10 M, Na2SiO3/NaOH ratio of 2.5, and AL/FA ratio of 0.5 when cured in an oven for 24 h at 80 °C, gave the optimum ratio for compressive strength of 13.7 MPa and water permeability of 2.1 cm/s. Both BA and CBA revealed a viable alternative aggregates for producing PGC and that the compressive strength of PGC made with CBA was 51% greater than cement pervious concrete containing NA. The results also showed that the reduction in runoff was due to the permeable concrete and decreased runoff with the increased rainfall intensity.
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4.
  • Arya, Pradyumn Kumar, et al. (author)
  • Development of high strength and lightweight Ti6Al4V5Cr alloy : Microstructure and mechanical characteristics
  • 2024
  • In: Journal of Materials Research and Technology. - : Elsevier Editora Ltda. - 2238-7854 .- 2214-0697. ; 28, s. 3526-3540
  • Journal article (peer-reviewed)abstract
    • This article explains development of high strength and lightweight Ti6Al4V5Cr alloy by μ-plasma powder additive manufacturing (μ-PPAM) process for automotive, aerospace, military, dies and moulds, and other similar applications. Microstructure, formation of phases, porosity, microhardness, tensile properties, abrasion resistance, and fracture toughness of multi-layer deposition of Ti6Al4V5Cr alloy are studied and compared with Ti6Al4V alloy. Results reveal that the presence of chromium in Ti6Al4V5Cr alloy refined the grains of its β-Ti and α-Ti phases, increased volume % of β-Ti phase, and promoted formation of its equiaxed grains. It also increased tensile strength, microhardness, abrasion resistance, and fracture toughness of Ti6Al4V5Cr alloy. It enhanced solid solution strengthening and formed higher hardness imparting intermetallic Cr2Ti phase and changed fracture mode to mixed ductile and brittle mode with larger size dimples, cleavage facets, and micropores. But it decreased formation temperature of β-Ti phase and % elongation as compared to Ti6Al4V alloy. Chromium and vanadium content in β-Ti phase of Ti6Al4V5Cr alloy is 7 % and 2.1 % more than its α-Ti phase. This study demonstrates that inclusion of limited amount of chromium content to Ti6Al4V5Cr alloy by μ-PPAM process is very beneficial to enhance microstructure, mechanical properties, crack propagation resistance, and abrasive wear resistance of the Ti6Al4V5Cr alloy. It makes Ti6Al4V5Cr alloy very useful in many commercial applications that require higher strength than Ti6Al4V alloy along with lightweight requirement.
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5.
  • Baghdadchi, Amir, 1994-, et al. (author)
  • Corrosion resistance and microstructure analysis of additively manufactured 22% chromium duplex stainless steel by laser metal deposition with wire
  • 2023
  • In: Journal of Materials Research and Technology. - 2238-7854 .- 2214-0697. ; 26, s. 6741-6756
  • Journal article (peer-reviewed)abstract
    • Microstructure characteristics and pitting corrosion of a duplex stainless steel (DSS) manufactured by laser metal deposition with wire (LMDw) were studied. The layer-by-layer LMDw process resulted in a mixed microstructure of predominantly ferrite with 2% austenite and chromium-rich nitrides, and reheated regions with ~33% austenite. The high cooling rate of LMDw restricted the distribution of Cr, Mo, and Ni, in ferrite and austenite, while N diffuses from ferrite to austenite. Subsequent heat treatment at 1100 C for 1 h resulted in homogenized microstructure, dissolution of nitrides, and balanced ferrite/austenite ratio. It also led to the redistribution of Cr and Mo to ferrite, and Ni and N to austenite. At room temperature, cyclic potentiodynamic polarization measurements in 1.0 M NaCl solution showed no significant differences in corrosion resistance between the as-deposited and heat-treated samples, despite the differences in terms of ferrite to austenite ratio and elemental distribution. Critical pitting temperature (CPT) was the lowest (60 C) for the predominantly ferritic microstructure with finely dispersed chromium-rich nitrides; while reheated area with ~33% austenite in as-deposited condition achieved higher critical temperature comparable to what was obtained after heat treatment (73 and 68 C, respectively). At temperatures above the CPT, selective dissolution of the ferrite after deposition was observed due to depletion of N, while after heat treatment, austenite preferentially dissolved due to Cr and Mo concentrating in ferrite. In summary, results demonstrate how microstructural differences in terms of ferrite-to-austenite ratio, distribution of corrosion-resistant elements, and presence of nitrides affect corrosion resistance of LMDw DSS.
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6.
  • Baghdadchi, Amir, 1994-, et al. (author)
  • Ductilization and grain refinement of AA7075-T651 alloy via stationary shoulder friction stir processing
  • 2023
  • In: Journal of Materials Research and Technology. - 2238-7854 .- 2214-0697. ; 27, s. 5360-5367
  • Journal article (peer-reviewed)abstract
    • This study investigates the microstructural evolution, mechanical properties, and fracture behavior of AA7075-T651 aluminium alloy subjected to stationary shoulder friction stir processing (SSFSP). SSFSP samples were produced at three different rotational speeds in a range of 600–1000 rpm. The results reveal that SSFSP leads to a uniform grain refinement within the Stir Zone (SZ), reducing the grain size to approximately 2–3 μm from the initial 15 μm in the base material (BM) irrespective of the probe rotational speeds. After SSFSP, the elongation increased by over 50 % at the cost of 10 % reduction in the ultimate tensile strength for all samples. It was worth to note that variations in tool rotational speed exhibited minimal influence on the microstructure and mechanical properties, offering wide range of probe rotational speeds. This could be attributed to the use of non-rotating shoulder with prob dominated microstructure in the SZ. Fractographic analysis confirmed the ductile nature of fractures, revealing development of fine dimples due to grain refinement. This work underscores the effectiveness of SSFSP in achieving significant grain refinement followed by drastic increase in ductility, which offers valuable insights for using stationary shoulder at wider range of rotational speed.
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7.
  • Bartels, Dominic, et al. (author)
  • Development of a novel wear-resistant WC-reinforced coating based on the case-hardening steel Bainidur AM for the substitution of carburizing heat treatments
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 26, s. 186-198
  • Journal article (peer-reviewed)abstract
    • Laser-based directed energy deposition of metals (DED-LB/M) supports the synthesis of functional materials with tailored properties and performance through in-situ modification of the alloying composition within the processing zone. In this investigation, a low-alloyed steel was modified stepwise to analyse the influence of carbon and tungsten carbide (WC) addition on the resulting material properties. A moderate carbon concentration of 0.4 wt.-% improved the average hardness (520 HV0.5). WC particles on the other hand were dissolved within the matrix and resulted in a fine microstructure with high hardness (780 HV0.5). A combined addition of carbon and WC led to the highest material hardness (840 HV0.5). Scratch tests showed that the wear resistance rises with increasing hardness but is improved the most by the addition of hard particles. Furthermore, these tests revealed an anisotropic abrasive wear resistance which correlates with the direction of the weld tracks. Loading the material parallel to the weld track direction led to a homogeneous wear. When the material is scratched perpendicularly to the weld tracks, an inhomogeneous wear with periodic characteristics occurred. The periodicity can be explained by the different microstructural characteristics and hardness at the transition zone between adjacent weld tracks deposited in DED-LB/M. For all materials, the transition between two weld tracks was characterized by a columnar microstructure with low microhardness while the adjacent weld tracks possessed a finer microstructure and higher microhardness. These microstructural differences were mirrored in scratch testing since wear peaks can be observed at the transition zone between two weld tracks.
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8.
  • Çelik, Ali İhsan, et al. (author)
  • Use of waste glass powder toward more sustainable geopolymer concrete
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 24, s. 8533-8546
  • Journal article (peer-reviewed)abstract
    • The influence of waste glass powder (WGP) with fly ash in certain proportions on geopolymer concrete (GPC) was investigated by exchanging different proportions of molarity and WGP percentages in GPC. For this objective, fly ash was altered with WGP having percentages of 10%, 20%, 30%, and 40%, and the effect of molarity of sodium hydroxide (NaOH) was examined. The compressive strength tests, splitting tensile tests, and flexural strength tests were conducted. The workability and setting time were also evaluated. With the addition of WGP, the workability for molarities (M) of 11, 13, and 16 NaOH reduced by an average of 17%, 10%, and 67%, respectively. The findings showed that the slump values decreased as the molarity and WGP percentages increased. Molarity significantly affected the setting time, but WGP had no effect on the setting time. Although high molarity increased the capacity, this had a noticeable negative effect on the setting time and workability. This study demonstrated that WGP had a slight negative effect on the capacity and workability. Furthermore, when the combined effects of WGP and NaOH molarity were taken into account, the use of 10% WGP with M13 NaOH was recommended to obtain the optimum sustainable GPC considering both fresh and hardening properties. Scanning electron microscopy (SEM) analysis was done on the samples, too.
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9.
  • Chaudhary, Bhavesh, et al. (author)
  • Friction stir powder additive manufacturing of Al 6061 alloy : Enhancing microstructure and mechanical properties by reducing thermal gradient
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 26, s. 1168-1184
  • Journal article (peer-reviewed)abstract
    • Additive manufacturing of Al alloys by fusion-based processes often leads to higher thermal gradients along the build direction resulting in anisotropy, and solidification-related defects such as porosity, hot-cracking, and lack of inter and intra-layer fusion. Therefore, this paper focuses on solid state multi-layer manufacturing of Al 6061 alloy by friction stir powder additive manufacturing (FSPAM) process and enhancing its microstructure and mechanical properties through reduction of thermal gradient along the build direction by maintaining the substrate close to its artificial aging temperature using external heat source in a close-loop with it. The continuous dynamic recrystallization along with reduced thermal gradient led to homogenous microstructure, fine and equiaxed grains of Al 6061 alloy multi-layer deposition. The inherent compressive forces in FSPAM process promoted intimate contact among the powder particles presenting 0.19% porosity. Energy dispersive spectroscopy showed absence of agglomeration of alloying elements due to better mixing of feedstock material beneath the tool. Phase analysis revealed presence of Al and hardening phase Mg2Si with slight shifting of peaks towards higher angle indicating compressive residual stresses. Tensile properties and microhardness of Al 6061 alloy are closer to AA6061-T4 and better than AA6061-O alloy. Reduced thermal gradient contributed to minimal variations in microhardness (8.8%) along the build direction. Fracture morphology analysis exhibited a significant number of dimples indicating ductile nature of Al 6061 alloy with 16.7% elongation. The study presented a new approach for manufacturing Al alloys using their feedstock in powder form and with improved microstructure and mechanical properties.
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10.
  • Ciurans Oset, Marina, 1993-, et al. (author)
  • Role of the microstructure and the residual strains on the mechanical properties of cast tungsten carbide produced by different methods
  • 2024
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 30, s. 3640-3649
  • Journal article (peer-reviewed)abstract
    • Cast tungsten carbide (CTC) is a biphasic, pearlitic-like structure composed of WC lamellae in a matrix of W2C. Besides excellent flowability, spherical CTC powders exhibit superior hardness and wear resistance. Nevertheless, the available literature generally fails to explain the physical mechanisms behind such a phenomenon. In the present work, the microstructure and the mechanical properties of the novel centrifugally-atomized spherical CTC have been extensively investigated. This material exhibited an extremely fine microstructure, with WC lamellae of 27-29 nm in thickness and bulk lattice strains of 1.0-1.4 %, resulting in a microindentation hardness of 31.4 ± 1.6 GPa. The results of this study clearly show that centrifugally-atomized CTC is mechanically superior to both spheroidized CTC and conventional cast-and-crushed CTC. In addition, the effect of a series of heat treatments on the bulk fracture toughness and the fatigue life of entire CTC particles was also investigated. The reduction of residual stresses in the bulk of particles upon annealing dramatically increased the indentation fracture toughness, whereas the bulk microindentation hardness remained essentially unaffected. Regarding the fatigue life of entire particles under uniaxial cyclic compressive loading, local phase transformation phenomena at the surface of the particles upon heat treatment were concluded to play the most critical role. Indeed, the cumulative fatigue damage was minimized in surface-carburized CTC powders, where compressive stresses were induced at the outermost surface.
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11.
  • Das, Atanu Kumar, et al. (author)
  • A review on wood powders in 3D printing : processes, properties and potential applications
  • 2021
  • In: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854 .- 2214-0697. ; 15, s. 241-255
  • Journal article (peer-reviewed)abstract
    • Three-dimensional (3D) printing is a technology that, for a multitude of raw materials, can be used in the production of complex structures. Many of the materials that currently dominate 3D printing (e.g. titanium, steel, plastics, and concrete) have issues with high costs and environmental sustainability. Wood powder is a widely available and renewable lignocellulosic material that, when used as a fibre component, can reduce the cost of 3D printed products. Wood powder in combination with synthetic or natural binders has potential for producing a wide variety of products and for prototyping. The use of natural binders along with wood powder can then enable more sustainable 3D printed products. However, 3D printing is an emerging technology in many applications and more research is needed. This review aims to provide insight into wood powder as a component in 3D printing, properties of resulting products, and the potential for future applications.
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12.
  • Das, Atanu Kumar, et al. (author)
  • A review on wood powders in 3D printing: processes, properties and potential applications
  • 2021
  • In: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854 .- 2214-0697. ; 15, s. 241-255
  • Research review (peer-reviewed)abstract
    • Three-dimensional (3D) printing is a technology that, for a multitude of raw materials, can be used in the production of complex structures. Many of the materials that currently dominate 3D printing (e.g. titanium, steel, plastics, and concrete) have issues with high costs and environmental sustainability. Wood powder is a widely available and renewable lignocellulosic material that, when used as a fibre component, can reduce the cost of 3D printed products. Wood powder in combination with synthetic or natural binders has potential for producing a wide variety of products and for prototyping. The use of natural binders along with wood powder can then enable more sustainable 3D printed products. However, 3D printing is an emerging technology in many applications and more research is needed. This review aims to provide insight into wood powder as a component in 3D printing, properties of resulting products, and the potential for future applications.
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13.
  • Derazkola, Hamed Aghajani, et al. (author)
  • The effect of temperature and strain rate on the mechanical properties and microstructure of super Cr13 martensitic stainless steel
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 24, s. 3464-3476
  • Journal article (peer-reviewed)abstract
    • In this study, the formability of super Cr13 martensitic stainless steel (MSS) is examined by means of hot tensile tests at different temperatures (900oC-1100oC) and t strain rates (0.01s-1-10s-1). The potential effect of strain rates and temperatures on the mechanical properties, microstructure and fracture surface of super Cr13 MSS were examined. The post-test analysis, which includes hardness measurements, X-ray diffraction (XRD), fracture analysis by scanning electron microscope (SEM), and Energy-dispersive X-ray spectroscopy (EDS), was carried out. Results show that ultimate tensile stress (UTS) decreases with temperature, this way, the highest UTS was obtained at 900oC-10s-1 (187MPa), while the lowest UTS (38MPa) was obtained in the 1100oC-0.01s-1 sample. By contrast the elongation of the material increases with strain rate, since the elongation of the sample at 900oC-10s-1 was near 16% and the elongation of the sample at 1100oC-0.01s-1 was 57%. The XRD and EDS analysis indicated that Cr23C6 and Cr2N are formed inside the microstructure of samples tested between 900oC and 1000oC, and these carbides are dissolved above 1000º C. Temperature affects also retained austenite which increases with temperature. Fractography analysis indicated that the δ-ferrite phase has a primary role in high-temperature rapture. Fracture surface evaluation of samples revealed semi-ductile fracture behaviour below 1000°C and low strain rates, while ductile fracture was detected on the tensile samples at temperatures higher than 1000°C and high strain rates. Furthermore, the ductility of super Cr13 MSS was increased by increasing strain rate.
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14.
  • Dhakal, Nayan, et al. (author)
  • Impact of processing defects on microstructure, surface quality, and tribological performance in 3D printed polymers
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 23, s. 1252-1272
  • Journal article (peer-reviewed)abstract
    • Additive manufacturing (AM), also known as three-dimensional (3D) printing, of polymer-based materials is growing as a time-efficient, economical, and environmentally sustainable technique for prototype development in load-bearing applications. This work investigates the defects arising from the processing in material extrusion-based AM of polymers and their impact on the part performance. The influence of raster angle orientation and printing speed on tribological characteristics, microstructure, and surface finish of acrylonitrile butadiene styrene (ABS) fabricated in a heated build chamber was studied. Comprehensive analysis with fractography and tomography revealed the formation, distribution, and locations of internal voids, while surface defects were studied with the topography analysis of as-printed surfaces. Surface roughness and tribological results show that printing speed can be optimally increased with a minimal impact on interlayer bonding and part performance. Increased printing speed allowed up to 58% effective reduction in printing time obtaining comparable mechanical properties at varying process parameters. 3D printed ABS exhibited dry sliding friction coefficients in the range of 0.18–0.23, whilst the maximum specific wear rate was 6.2 × 10−5 mm3/Nm. Higher surface roughness and increased printing speed exhibited delayed running-in during dry sliding, while insignificant influence was observed for steady-state friction and wear behaviors. The findings indicate that improved surface finish and reduced internal defects can be achieved with a controlled build environment allowing for higher printing speed. The observations in this study are evidence that 3D printing can be adapted for the sustainable manufacturing of polymeric components for tribological applications.
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15.
  • Kim, Shin, et al. (author)
  • Development of boron doped diamond electrodes material for heavy metal ion sensor with high sensitivity and durability
  • 2023
  • In: JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY. - : Elsevier BV. - 2238-7854 .- 2214-0697. ; 23, s. 1375-1385
  • Journal article (peer-reviewed)abstract
    • We report on the optimized substrate pretreatment and deposition process conditions for boron-doped diamond (BDD) electrodes fabricated by hot-filament chemical vapor deposition (HFCVD). The optimized BDD electrode with a doping concentration of 8000 ppm showed high accuracy and precision in detecting Cd(II), Pb(II), and Cu(II) ions. In addition, this demonstrates excellent selectivity against external metal ions under the optimized stripping voltammetry measurement conditions. The detection limits of the target ions of Cd(II), Pb(II), and Cu(II) were 0.55 (+/- 0.05), 0.43 (+/- 0.04), and 0.74 (+/- 0.06) mg/L (S/N = 3), respectively. In real samples spiked with 100 mg/L Cd(II), Pb(II), and Cu(II), both the accuracy and precision of the BDD electrode were within 5%; the interference with organic matter was also negligible. The excellent selectivity and long-term stability indicate that the BDD electrode developed in this study are potentially useful for online water environment monitoring systems.
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16.
  • Lindwall, Johan, et al. (author)
  • Simulation of phase evolution in a Zr-based glass forming alloy during multiple laser remelting
  • 2022
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 16, s. 1165-1178
  • Journal article (peer-reviewed)abstract
    • Additive manufacturing by laser-based powder bed fusion is a promising technique for bulk metallic glass production. But, reheating by deposition of subsequent layers may cause local crystallisation of the alloy. To investigate the crystalline phase evolution during laser scanning of a Zr-based metallic glass-forming alloy, a simulation strategy based on the finite element method and the classical nucleation theory has been developed and compared with experimental results from multiple laser remelting of a single-track. Multiple laser remelting of a single-track demonstrates the crystallisation behaviour by the influence of thermal history in the reheated material. Scanning electron microscopy and transmission electron microscopy reveals the crystalline phase evolution in the heat affected zone after each laser scan. A trend can be observed where repeated remelting results in an increased crystalline volume fraction with larger crystals in the heat affected zone, both in simulation and experiment. A gradient of cluster number density and mean radius can also be predicted by the model, with good correlation to the experiments. Prediction of crystallisation, as presented in this work, can be a useful tool to aid the development of process parameters during additive manufacturing for bulk metallic glass formation.
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17.
  • Majeed, Samadar S., et al. (author)
  • Development of ultra-lightweight foamed concrete modified with silicon dioxide (SiO2) nanoparticles: Appraisal of transport, mechanical, thermal, and microstructural properties
  • 2024
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 30, s. 3308-3327
  • Journal article (peer-reviewed)abstract
    • Over the last few decades, researchers have devoted significant consideration to the use of nanoscale elements in concrete. Silicon dioxide nanoparticles (SDNs) have been a popular subject of study among the several types of nanoparticles. This article describes the findings of a laboratory investigation that examined the properties of ultra-lightweight foamed concrete (ULFC) including different proportions of SDNs. Wide range of the properties was evaluated specifically the slump flow, density, consistency, flexural strength, modulus of elasticity, compressive strength, split tensile strength, thermal properties, porosity, water absorption, sorptivity, intrinsic air permeability, and chloride diffusion. Additionally, the scanning electron microscopy (SEM) and pore distributions analyses of different mixes were done. Results confirmed a noticeable increase in the mechanical properties of ULFC, with respective improvements in the 28-day compressive, split tensile, and flexural strengths of up to 70.49%, 76.19%, and 51.51%, respectively, at 1.5% of the SDNs inclusion. However, further increases in the SDNs percentage did not result in remarkable enhancements. As the SDN percentage increased from 1.5% to 2.5%, the ULFC’s sorptivity, porosity, water absorption, intrinsic air permeability, and chloride diffusion showed substantial improvements. When compared to the control sample, ULFC with SDNs demonstrated higher thermal conductivity values. The reason for this occurrence was determined to be the smaller pore size observed in the ULFC specimens containing SDNs. A great adjustment in the distribution of pore diameters was witnessed in the ULFC mixes when the percentages of SDNs were adjusted. The ULFC specimens, which included SDNs at the percentages of 0.5%, 1.0%, and 1.5%, indicated a reduction in the total number of large voids measuring 500 nm or more, compared to the control ULFC specimen. The findings of this study highlight the potential benefits of incorporating SDNs into ULFC, which may improve its overall properties.
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18.
  • Paidar, M., et al. (author)
  • Dissimilar modified friction stir clinching of AA2024-AA6061 aluminum alloys : Effects of materials positioning
  • 2020
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 9:3, s. 6037-6047
  • Journal article (peer-reviewed)abstract
    • Modified friction stir clinching (MFSC) process was employed to joint dissimilar AA2024-T3 and AA6061-T6 Al sheets by interchanging the upper and the lower sheets during the joining process. The material flow, microstructure, tensile strength and fracture behaviors of the MFSC joints were studied. The results reveal that material positioning significantly affects the material flow behavior of the MFSC joint due to the disparity in the properties (flow stress) of the AA2024-T3 and AA6061-T6 Al alloys. The flow-induced hook path and proximity of hook tip to the geometric differential flow-induced defect (at the refilled end of the keyhole) are undesirable in the welded AA6061-T6/AA2024-T3 joint as compared to the AA2024-T3/AA6061-T6 joint. The microstructure (precipitate dispersion, dislocation density, and tangles), hardness distribution, and fracture morphology of the joints are altered by the material positioning-induced flow behavior. Improved tensile strength (97.88 MPa) is obtained in the AA2024-T3/AA6061-T6 joint as compared to the AA6061-T6/AA2024-T3 joint (86.65 MPa). (C) 2020 The Authors. Published by Elsevier B.V.
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19.
  • Saadat, Nazmus, et al. (author)
  • Enhancing performance of advanced fuel cell design with functional energy materials and process
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 26, s. 1723-1735
  • Journal article (peer-reviewed)abstract
    • Efficiency enhancement of hydrogen based electric powertrain is becoming highly relevant for medium to heavy duty transportation due to advantages of eminent electrochemical cell design and advances in infrastructure accessibility. Herein, a facile and highly effective fabrication process has been reported for the first time to demonstrate an outstanding mechanical strength and electrical conductivity simultaneously in the carbon rich composite designed to enhance the fuel cell performance. Improvement of composites with different advanced reinforced materials such as carbon veil, recycled carbon fiber as well as functional additives such as carbon black, multiwalled nanotube, etc. Was investigated through a holistic approach of optimized parameters. Advanced composite plates have been designed to be mechanically flexible, electrically conductive and cost effective; this newly designed composite for bipolar plate supersedes by far the US Department of Energy (DOE) target for fuel cell bipolar plate with a flexural strength of over 64 MPa and exceeding electrical conductivity of 200 S/cm. Notably, tuned process parameters as well as novel architecture of materials such as continuous carbon fiber and carbon veil can facilitate the fabrication of a light-weight high-performance carbon polymer composite for a wide range of applications including battery electrodes, supercapacitors, fuel cells and solar cell.
  •  
20.
  • Yu, Yang, et al. (author)
  • Research of TE behaviour and compression property of porous Ni–Al–Cr intermetallic compounds in the β phase region
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier Editora Ltda. - 2238-7854 .- 2214-0697. ; 25, s. 3537-3550
  • Journal article (peer-reviewed)abstract
    • Ni–Al–Cr alloys in the β phase (B2–NiAl) region exhibit remarkable stability and mechanical property. Through thermal explosion (TE) reaction, Ni–Al–Cr intermetallic compounds with high porosity can be obtained. In this study, the focus lies on analyzing the macroscopic morphology, microstructure, phase distribution, TE behaviour, and the mechanical property of porous Ni–Al–Cr in the β phase region. Following the TE reaction, the Al-rich sintered product demonstrates a uniform phase composition and high porosity, reaching 44.39%. The vigorous TE reaction promotes the formation of interconnected pores, while the high porosity structure compromises the mechanical properties of the sample. Conversely, the Al-poor sintered product, due to a moderate TE reaction and low porosity structure, maintains its complete morphology and exhibits excellent compression resistance (yield stress reaching 538 MPa). This study offers valuable insights for the fabrication of porous Ni–Al–Cr materials with exceptional structure and performance.
  •  
21.
  • Özkılıç, Yasin Onuralp, et al. (author)
  • Optimum usage of waste marble powder to reduce use of cement toward eco-friendly concrete
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854 .- 2214-0697. ; 25, s. 4799-4819
  • Journal article (peer-reviewed)abstract
    • In this study, waste marble powder (WMP) was used to replace cement of concrete in specific amounts. To accomplish this aim, WMP was replaced at 10%, 20%, 30%, and 40% of the cement weight, and a reference concrete sample without WMP (REF) was created to compare the compressive strength, splitting tensile strength, and flexural strength. The replacement of WMP at 10%, 20%, 30%, and 40% of the cement weight resulted in 5.7%, 21.7%, 38.1%, and 43.6% decreases in the compressive strength compared with REF. Furthermore, the splitting tensile strength results commonly followed the same trend as the compressive strength. However, WMP at 10%, 20%, 30%, and 40% led to 5.3%, 8.6%, 19.4%, and 26.7% decreases in the flexural strength compared with REF. In addition, three different calculations, ranging from simple to complex, were proposed to compute mechanical resistances of concrete with WMP. These proposed calculations for practical applications were validated using values from the literature and the implications obtained from the current research. While the simple calculations were based on the strength of REF and the WMP percentages, the complex calculations were dependent on the design of the concrete mixture, age of the samples, and the WMP percentages. For the complex calculations, the ANN approach was used with the help of the coefficient of determination (R2) for the K-fold cross validation method. All the proposed methods provided high accurate estimation to predict the properties of concrete with WMP. Based on the studies, utilizing 10% WMP as the replacement of cement is recommended to obtain the optimum benefits considering both mechanical and environmental aspects. Moreover, scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analyses were then conducted to observe the interaction of WMP in concrete. According to the SEM analyses, some pores were detected and the interfacial transition zone was observed in the reaction zone. On the other hand, based on the EDX analyses, the presence of WMP in concrete was manifested by the presence of high levels of calcium.
  •  
22.
  • Sathvik, S., et al. (author)
  • Evaluation of asphalt binder and mixture properties utilizing fish scale powder as a biomodifier
  • 2024
  • In: Case Studies in Construction Materials. - : Elsevier. - 2214-5095 .- 2214-0697. ; 20
  • Journal article (peer-reviewed)abstract
    • Fish represents an abundant and underutilized waste product from the fishing industry. This study investigated the effects of incorporating fish scale powder (FSP) at various dosages (3%, 6%, 9%, and 12%) on the properties of asphalt binder and mixtures. Conventional tests, viscosity, storage stability, Fourier transform infrared spectroscopy, and multiple stress creep recovery tests were conducted on the binder. Mix design, wheel tracking, indirect tensile strength, fatigue, and ultrasonic pulse velocity tests were evaluated for the asphalt mixtures. The results showed that FSP increased the binder’s stiffness and reduced the temperature susceptibility but compromised the low-temperature performance and workability regardless of the dosages. The storage stability test results demonstrated the improved high-temperature storage stability. In the mixtures, the permanent deformation resistance enhanced with increasing the FSP content, decreasing the rut depth from 4.3 mm for the control sample to 2.9 mm at 12% FSP. The moisture damage resistance, indicated by the tensile strength ratio, increased from 90% for the control sample to 94.1% at 12% FSP. However, the fatigue life decreased from 14010 cycles for the control sample to 11190 cycles at 12% FSP. The dynamic and elastic modulus values before conditioning increased with higher FSP dosages, and this increasing trend was also observed after conditioning, signifying greater stiffness retention and moisture resistance of the asphalt mixtures containing higher amounts of FSP. Numerically, the 6–9% FSP range offered the optimum balance, improving the rutting resistance by 18% and the moisture resistance by 3.2% compared to those of the control sample, while limiting the fatigue life to 12% and maintaining the workability. Overall, FSP has potential for use as an asphalt biomodifier by transforming an environmental liability into a value-added sustainable paving material.
  •  
23.
  • Abutalib, M. M., et al. (author)
  • Fe3O4/Co3O4-TiO2 S-scheme photocatalyst for degradation of organic pollutants and H-2 production under natural sunlight
  • 2022
  • In: Journal of Materials Research and Technology. - : Elsevier Editora Ltda. - 2238-7854. ; 20, s. 1043-1056
  • Journal article (peer-reviewed)abstract
    • Sunlight responsible mono-and co-doped TiO2 nanoparticles (Con+ and Fen+) were prepared via sol-gel technique. The X-ray diffraction (XRD) results showed no phase change of TiO2 was observed after the addition of Con+ and Fen+ ions. Diffuse reflectance spectra (DRS) results showed a significant red-shift of the absorption edge after doping TiO2 by Co(n )and Fen+ and the band gap energy reduced sharply from 3.10 to 1.72 eV. X-ray photoelectron spectroscopy (XPS) results emphasized the existence of multivalent states of Co2+, Co3+, Fe2+ and Fe3+. The results of ultraviolet photoelectron spectroscopy (UPS), work function, electron spin resonance (ESR) illustrated the Fe3O4/Co3O4-TiO2 formed of ternary hetero-junctions. The photocatalytic performance of the prepared photocatalysts was determined for photodegradation of tetracycline (TC) and phenol (Pl) and production of hydrogen. The results illustrated the existence of multivalent states of Fe and Co ions (Co2+, Co3+, Fe2+ and Fe3+) together improved the solar light absorption, inhibited the recombination of photo -generated charges and consequently enhanced the photocatalytic efficiency of TiO2 compared with mono-doped TiO2 (Co3O4/TiO2 and Fe3O4/TiO2). The sample with 5%Fe3O4/ Co(3)O(4)4-TiO2 showed the highest photoactivity. The mineralization (TOC), photodegradation mechanism and reusability of prepared photocatalysts were also studied. The Fe3O4/Co3O4-TiO2 nanoparticles showed high photoactivity and stability and can be adopted as a promising materials for different environmental and H-2 production applications. (C) 2022 The Author(s). Published by Elsevier B.V.
  •  
24.
  • Ahmed, Hesham, et al. (author)
  • Injection of H2-rich carbonaceous materials into the blast furnace : devolatilization, gasification and combustion characteristics and effect of increased H2–H2O on iron ore pellets reducibility
  • 2020
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 9:6, s. 16029-16037
  • Journal article (peer-reviewed)abstract
    • Increasing the share of hydrogen in reduction of iron oxide in the blast furnace iron making will directly reduce the share of blast furnace greenhouse gas emissions. In the present study, injection of H2-rich biomass and plastic materials was studied in terms of its devolatilization, gasification and combustion characteristics. The released gases were identified using mass spectroscopy attached to a thermogravimetric analyzer and the corresponding kinetics parameters were estimated.The devolatilization was found to occur through two or more steps. The first step is always associated with the release of CO2, CO, H2, H2O and hydrocarbons while only CO and H2 were detected during the later steps. Combustion and gasification starting temperatures of char of H2-rich carbonaceous materials were lower than that of pulverized coal char by ≥ 100 °C. The estimated activation energies suggested that, under the present conditions, devolatilization, gasification and combustion were chemically controlled. Carbon reactivity of the char of the studied H2-rich carbonaceous materials were higher than that of pulverized coal. Moreover, increased H2–H2O content in the blast furnace gas, due to injected H2-rich carbonaceous materials, was found to improve the iron ore pellets reduction kinetics.
  •  
25.
  • Akman, Adnan, et al. (author)
  • Effect of minor gallium addition on corrosion, passivity, and antibacterial behaviour of novel β-type Ti–Nb alloys
  • 2023
  • In: Journal of Materials Research and Technology. - 2238-7854. ; 25, s. 4110-4124
  • Journal article (peer-reviewed)abstract
    • Metastable Ti–Nb alloys are promising bone-implant materials due to improved mechanical biofunctionality and biocompatibility. To overcome increasing bacterial infection risk, alloying with antibacterial elements is a promising strategy. This study investigates the effect of minor gallium (Ga) additions (4, 8 wt% Ga) to as-cast and solution-treated β-type Ti–45Nb-based alloy (96(Ti–45Nb)-4Ga, 92(Ti–45Nb)-8Ga (wt.%)) on corrosion and passive film properties, as well as cytocompatibility and antibacterial activity. The electrochemical properties were evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analyses in phosphate-buffered saline (PBS). X-ray photoelectron spectroscopy (XPS) was performed to analyze the chemical composition of passive films. Early adhesion and viability of macrophages and Staphylococcus aureus were assessed by nucleocounting and colony-forming unit counting, respectively. The results showed that high corrosion resistance and passive film properties of Ti–45Nb are retained and even slightly improved with Ga. EIS results revealed that Ga addition improves the passive film resistance. XPS measurements of 92(Ti–45Nb)-8Ga show that the passive film contains Ti-, Nb- and Ga-based oxides, implying the formation of mixed (Ti–Nb-Ga) oxides. In addition, marginal Ga ion release rate was detected under free corrosion conditions. Therefore, it can be assumed that Ga species may contribute to passive film formation on Ga-containing alloys. The 92(Ti–45Nb)-8Ga elicited an antibacterial effect against S. aureus compared to cp-Ti at 4 h. Moreover, Ga-containing alloys showed good cytocompatibility with THP-1 macrophages at 24 h. In conclusion, it was demonstrated that Ga additions to Ti–45Nb are beneficial to corrosion resistance and showed promising initial host and bacterial interactions.
  •  
26.
  • Alghamdi, Haifa Mohammed, et al. (author)
  • Modification and development of high bioactivities and environmentally safe polymer nanocomposites doped by Ni/ZnO nanohybrid for food packaging applications
  • 2022
  • In: JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T. - : ELSEVIER. - 2238-7854. ; 19, s. 3421-3432
  • Journal article (peer-reviewed)abstract
    • This study aimed to develop a sodium alginate (50%NaAlg)/polyethylene oxide (50%PEO) blend-based film loaded with nickel and zinc oxide nanoparticles (Ni/ZnO NPs) as a rein-forcing and antibacterial agent. The Ni/ZnO NPs as nanohybrid were synthesized via the sol-gel method at different concentrations (0.0, 5.0, 10.0, 15.0, 20.0 wt.%). The solution cast approach was utilized to create polymer nanocomposites samples from NaAlg/PEO/Ni/ZnO NPs for application in bioactive food packaging. The films were characterized using various procedures in detail. With the addition of Ni/ZnO, the XRD confirms the expansion of amorphous nature within NaAlg/PEO. The crystallinity degree of NaAlg/PEO-Ni/ZnO nanocomposite were decreased from 47 to 25%. The interactions between the compo-nents of NaAlg/PEO and Ni/ZnO NPs are revealed by FTIR findings. The bio-degradable nanocomposites dielectric behavior, electrical conductivity as well as mechanical prop-erties, were investigated. With the addition of Ni/ZnO NPs, the dielectric and AC conduc-tivity properties of the nanocomposites improved with the increase in the concentrations of Ni/ZnO NPs. The loading of Ni/ZnO nanoparticles increased the mechanical character-istics of the nanocomposite, such as tensile strength increased from 30.18 to 72.34, stiff-ness increased from 18.78 to 38.42, and Youngs Modulus increased from 8.24 to 29.76. The antibacterial activity of nanocomposites films was examined against Gram-negative (Escherichia coli), Gram-positive (Staphylococcus aureus), Aspergillus niger (fungus) and Candida albicans (yeast). Though the tested NaAlg/PEO blend did not indicate any activity against the microbial strains, when Ni/ZnO NPs were added, activity against E. coli, S. aureus, fungus and yeast was enhanced. The water solubility of nanocomposites films reduced from 65.5% to 9.81% with increasing of Ni/ZnO NPs content. The present study shown that NaAlg/PEO-Ni/ZnO films were more effective in inhibiting bacteria growth than pure NaAlg/PEO film, confirming the nanocomposites films potential application as anti-microbial food packaging.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
  •  
27.
  • Alhourani, A., et al. (author)
  • Thermal modeling of friction stir welding of thick high-density polyethylene plates
  • 2024
  • In: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854. ; 28, s. 4186-4198
  • Journal article (peer-reviewed)abstract
    • The process temperatures in the friction stir welding of thick polymer plates play a significant role in the joint's quality since the process is characterized by mixed solid and viscous flow states. The heat generation mechanism in each state is fundamentally different, with heat being generated by friction in the solid-state and by viscous shear flow in the viscous state. In this study, the heat generation and dissipation in the friction stir welding of 14 mm thick high-density polyethylene plates were studied numerically through solving the direct heat conduction problem. Two models of heat generation were used in the numerical solution and the effect of the pin rotational speed on the process temperatures was investigated. It was shown that the utilization of a mixed heat generation model consisting of both the solid state and the viscous shear flow considerably improves the numerical model predictions. The temperature predictions were validated through welding experiments and showed a temperature difference of 3 %. Furthermore, it was found that the welding process stabilizes at rotational speeds higher than 800 rpm, where no considerable change occurs in the volume of the viscous flow region and the welding power requirement. The numerical results based on the combined solid-viscous heat model were in good agreement with the experimental thermal histories.
  •  
28.
  • Aslam, Marryam, et al. (author)
  • Physical characteristics of CdZrO3 perovskite at different pressure for optoelectronic application
  • 2020
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 9:5, s. 9965-9971
  • Journal article (peer-reviewed)abstract
    • A comprehensive investigation of the physical characteristics of any material provides beneficial information regarding its application viewpoint in different industries. Herein, we report the tunable mechanical and optoelectronic properties of cubic CdZrO3 under variable pressure up to 80 GPa using density functional theory (DFT). The pressure-induced band gap engineering reveals a fantastic fact of transformation of the indirect to direct band gap with increasing pressure. The dielectric response disclosed that optical parameters dragged towards higher energy with an increase of pressure, which unveiled the potential of CdZrO3 for optoelectronic applications. Effective change in optoelectronic is attributed to indirect to direct band gap transition. This study provides a gateway to how the optoelectronic properties of cubic CdZrO3 could be tuned by employing external pressure.
  •  
29.
  • Atefi, S., et al. (author)
  • A study on microstructure development and mechanical properties of pure copper subjected to severe plastic deformation by the ECAP-Conform process
  • 2022
  • In: JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T. - : Elsevier. - 2238-7854. ; 21, s. 1614-1629
  • Journal article (peer-reviewed)abstract
    • Commercially pure copper rod was successfully subjected to severe plastic deformation by applying the continuous equal channel angular pressing (ECAP-Conform) method at room temperature. Microstructural characterizations of copper rod samples at various stages of plastic deformation were carried out by optical microscopy and electron backscatter diffraction methods. X-ray diffractometry and Kernal average misorientation were used for dislocation density estimations. Microstructural evaluations revealed grain size change of 30 mm for the initial annealed copper rod to less than 5 mm and even 100 nm for severely deformed samples. Mechanical behaviors of samples after different deformation stages were characterized using tensile and hardness tests. The ultimate tensile strength of the severely deformed copper rod was increased threefold by ECAP-Conform while elongation halved in comparison to the initial annealed copper. Low-temperature annealing of severely plastic deformed samples led to bi-modal grain size distribution and lowering of strength accompanied by the increase of elongation. Tensile properties of severely deformed and then annealed copper samples showed around a 40% increase in both ultimate tensile strength and elongation in comparison to the initial annealed copper rod.
  •  
30.
  • Baghdadchi, Amir, 1994-, et al. (author)
  • Identification and quantification of martensite in ferritic-austenitic stainless steels and welds
  • 2021
  • In: Journal of Materials Research and Technology. - : Elsevier Editora Ltda. - 2238-7854. ; 15, s. 3610-3621
  • Journal article (peer-reviewed)abstract
    • This paper aims at the phase identification and quantification in transformation induced plasticity duplex stainless steel (TDSS) base and weld metal containing ferrite, austenite, and martensite. Light optical microscopy (LOM) and electron backscatter diffraction (EBSD) analysis were employed to analyze phases. Samples were either mechanically or electrolytically polished to study the effect of the preparation technique. Mechanical polishing produced up to 26% strain-induced martensite. Electrolytic polishing with 150 g citric acid, 300 g distilled water, 600 mL H3PO4, and 450 mL H2SO4 resulted in martensite free surfaces, providing high-quality samples for EBSD analysis. Martensite identification was challenging both with LOM, due to the similar etching response of ferrite and martensite, and with EBSD, due to the similar lattice structures of ferrite and martensite. An optimized Beraha color etching procedure was developed that etched martensite distinctively. A novel step-by-step EBSD methodology was also introduced considering grain size and orientation, which successfully identified and quantified martensite as well as ferrite and austenite in the studied TDSS. Although here applied to a TDSS, the presented EBSD methodology is general and can, in combination with knowledge of the metallurgy of the specific material and with suitable adaption, be applied to a multitude of multiphase materials. It is also general in the sense that it can be used for base material and weld metals as well as additive manufactured materials.
  •  
31.
  • Bahrami, Ataallah, et al. (author)
  • Effect of different reagent regime on the kinetic model and recovery in gilsonite flotation
  • 2019
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 8:5, s. 4498-4509
  • Journal article (peer-reviewed)abstract
    • Gilsonite is a natural fossil resource, similar to an oil asphalt high in asphaltenes. To determine the effect of reagent regime on the kinetic order and rate of flotation for a gilsonite sample, experiments were carried out in both rougher and cleaner flotation process. Experiments were conducted using different combinations of reagent: Oil-MIBC; gasoline-pine oil; and one test without any collector and frother. According to results, kinetic in the test performed using the oil-MIBC and without any collector and frother were found to be first-order unlike the kinetic in the test conducted using the gasoline-pine oil. Five kinetic models were applied to the modeling of data from the flotation tests by using MATrix LABoratory software. The results show that all experiments are highly in compliance with all models. The kinetic constants (k) in rougher stage were calculated as 0.1548 (s-1), 0.2300 (s-1) and 0.2163 (s-1) for oil-MIBC, gasoline-pine oil, and test without any collector and frother, respectively. These amounts in the cleaner stage were 0.0450 (s-1), 0.1589 (s-1) and 0.0284 (s-1), respectively. The relationship between k, maximum combustible recovery (R) and particle size was also studied. The results showed that the R and k were obtained with a coarse particle size of (-250 + 106) μm in the rougher and (-850 + 500) μm in cleaner flotation processes.
  •  
32.
  • Cao, Yu, 1969, et al. (author)
  • The influence of temperatures and strain rates on the mechanical behavior of dual phase steel in different conditions
  • 2015
  • In: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854. ; 4:1, s. 68-74
  • Journal article (peer-reviewed)abstract
    • This study deals with the mechanical behavior of DP steel. A commercial dual phase steel (DP 800) was strained to 3.5% followed by annealing at 180 degrees C for 30 min to simulate the pressing of the plates and the paint bake cycle involved in the manufacturing process of automobile body structures. The effect of temperarure and strain rate on the machanical behavior of this material was investigated by uniaxial tensile tests, covering applicable temperatures (-60 degree C to +100 degree C) and strain rates (1x10exp-4 s-1 to 1x10exp+2 s-1) experienced in automotive crash situations. Yield and ultimate tensile strength, ductility, temperature effects and strain rate sensitivity as well as strain rate hardening rate have been determined and discussed.
  •  
33.
  • Chaudhari, Rakesh, et al. (author)
  • Effect of multi-walled structure on microstructure and mechanical properties of 1.25Cr-1.0Mo steel fabricated by GMAW-based WAAM using metal-cored wire
  • 2022
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 21, s. 3386-3396
  • Journal article (peer-reviewed)abstract
    • Wire-arc additive manufacturing (WAAM) offers multiple benefits, such as high metal deposition, low capital cost, suitable mechanical properties, and reasonable costs. In the present work, Gas metal arc welding (GMAW) based WAAM was employed to manufacture a multi-walled component of 1.25Cr-0.5Mo at optimized parameters using metal-cored wire. The fabricated multi-walled structure was observed with seamless fusion and free from disbonding. The fabricated multi-walled component was studied through microstructure investigations, mechanical properties such as microhardness (MH), tensile test, and impact test at various positions (top side, middle side, and bottom side) of the built structure. Microstructure results have shown a tempered martensite structure in the bottom zone with coarse grains and finer microstructures in the middle and top zones. MH values throughout the component were uniform and thus indicated a similar nature to the multi-walled component. A comparison of tensile properties was carried out among the results of metal-cored wires and multi-walled structures to check the internal eminence of the obtained component. For all sides of the multi-walled structure, all the tensile properties were found to be in the range values of 1.25Cr-0.5Mo metal-cored wire. The results of all three conditions for impact toughness showed far better strength than the requirement. Fracture surface morphologies of tensile and impact test parts showed the presence of large dimples with the homogenous distribution. Thus, all the obtained results have suggested the suitability of the GMAWAM process for the fabrication of a multi-walled structure of 1.25Cr-0.5Mo metal-cored wire for various industrial applications.  
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34.
  • Chaudhary, Bhavesh, et al. (author)
  • Exploring temperature-controlled friction stir powder additive manufacturing process for multi-layer deposition of aluminum alloys
  • 2022
  • In: Journal of Materials Research and Technology - JMR&T. - : Elsevier. - 2238-7854. ; 20, s. 260-268
  • Journal article (peer-reviewed)abstract
    • This paper presents preliminary study on multi-layer deposition of aerospace grade Al 6061 alloy by novel friction stir powder additive manufacturing process. Minimum temperature of deposition was in-situ maintained using close loop temperature-controlled system for minimizing thermal gradient in the build direction. Maximum temperature during the deposition was monitored in-situ using pyrometer and thermal imaging camera. Use of a tool with circumferential and radial grooves and continuous external heating facilitated smooth three-layer deposition of Al 6061 alloy with 60% deposition efficiency and 417 degrees C as maximum deposition temperature. Larger value of temperature at deposition zone improved material flowability and deposition quality. Microstructure of multi-layer deposition found to consist of fine sub-grains. Element analysis showed uniform distribution of major alloying elements in it. Phase analysis revealed Al along with Mg2Si hardening precipitates. Tensile strength and microhardness were close to the commercially available wrought AA6061-T4 alloy. It showed ductility with 16% elongation. The presented process is a viable alternative to fusion-based additive manufacturing processes for multi-layer depositions of aerospace grade and other lightweight alloys which are difficult-to-additively-manufacture. 
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35.
  • Chelgani, Saeed Chehreh, et al. (author)
  • A comparative study on the effects of dry and wet grinding on mineral flotation separation : a review
  • 2019
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 8:5, s. 5004-5011
  • Research review (peer-reviewed)abstract
    • Water scarcity dictates to limit the use of water in ore processing plants particularly in arid regions. Since wet grinding is the most common method for particle size reduction and mineral liberation, there is a lack of understanding about the effects of dry grinding on downstream separation processes such as flotation. This manuscript compiles various effects of dry grinding on flotation and compares them with wet grinding. Dry grinding consumes higher energy and produces wider particle size distributions compared with wet grinding. It significantly decreases the rate of media consumption and liner wear; thus, the contamination of pulp for flotation separation is lower after dry grinding. Surface roughness, particle agglomeration, and surface oxidation are higher in dry grinding than wet grinding, which all these effects on the flotation process. Moreover, dry ground samples in the pulp phase correlate with higher Eh and dissolved oxygen concentration. Therefore, dry grinding can alter the floatability of minerals. This review thoroughly assesses various approaches for flotation separation of different minerals, which have been drily ground, and provides perspectives for further future investigations.
  •  
36.
  • Chen, Xu, et al. (author)
  • Ductility deterioration induced by L21 phase in ferritic alloy through Ti addition
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier Editora Ltda. - 2238-7854. ; 25, s. 3273-3284
  • Journal article (peer-reviewed)abstract
    • Ductility deterioration induced by L21-Ni2AlTi precipitates in the aged ferritic alloys was examined systematically by using a combination of scanning transmission electron microscope (STEM), mechanical tests and first-principles thermodynamic calculations. The experimental studies revealed that the strength and hardness of the aged Fe–10Cr–5Ni–1Al–1Ti ferritic alloy containing B2–NiAl and L21-Ni2AlTi precipitates were higher than that of the aged Fe–10Cr–5Ni–1Al ferritic alloy containing NiAl precipitates, whereas the elongation-to-failure decreased dramatically from 9.3% to 0.3% indicating an obvious ductility deterioration due to the formation of L21-Ni2AlTi precipitates. This was also confirmed by the observation of fracture transition mode from dimpled failure to cleavage failure. The first-principles calculations, concerning the precipitate/matrix interface, were carried out to provide a theoretical analysis for the ductile–brittle transition by means of empirical ductility criteria ratios G/B and (C12–C44)/B as well as cleavage energy. The cleavage energy results indicated an intrinsic brittleness of the L21-Ni2AlTi phase and the L21-Ni2AlTi/BCC-Fe interface. Our analysis revealed that the intrinsic brittleness of L21-Ni2AlTi phase and L21-Ni2AlTi/BCC-Fe interface plays a vital role in determining the deformation behavior of the aged Fe–10Cr–5Ni–1Al–1Ti alloy.
  •  
37.
  • Chipakwe, Vitalis, et al. (author)
  • A critical review on the mechanisms of chemical additives used in grinding and their effects on the downstream processes
  • 2020
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 9:4, s. 8148-8162
  • Research review (peer-reviewed)abstract
    • Grinding aids (GAs) have been an important advent in the comminution circuits. Over the last few decades, in order to address the high energy consumption and scarcity of potable water for mineral processing, chemical additives have become a promising alternative. Using GAs can have some advantages such as enhancing grinding efficiency, reducing water usage, improving material flowability, and narrowing the particle size distribution of the grinding products. A study on the effect of GAs on size reduction units is crucial for the beneficiation value chain of minerals and the impact on downstream processes. However, our understanding of the effects of these materials on the particle size reduction is quite limited. This article analyses the literature, which used GAs and provides a comprehensive review of their applications in the ore beneficiation processes. The outcomes of this investigation indicated that the current understanding on the mechanism of GA effects focuses only on their impacts on the product fineness and size distribution, and neglecting the aspect of energy expended and physicochemical environment. The application of GAs is mainly for rationalisation of energy where the type of reagent, pH, and ionic strength of the grinding environment is important. Gaps in knowledge of GAs are discussed in the context of addressing their use in the mineral industry, considering the mechanism of their effect, effect on grinding efficiency, and effect on the downstream processes. Addressing these gaps will pave the way for the application of GAs in improving size reduction efficiencies, which ultimately reduces environmental impacts.
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38.
  • Dalibon, Eugenia. L., et al. (author)
  • Characterization of DLC coatings over nitrided stainless steel with and without nitriding pre-treatment using annealing cycles
  • 2019
  • In: JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMRandT. - : ELSEVIER SCIENCE BV. - 2238-7854. ; 8:2, s. 1653-1662
  • Journal article (peer-reviewed)abstract
    • Amorphous hydrogenated diamond-like carbon (DLC) coatings were deposited using plasma assisted chemical vapour deposition (PACVD) on precipitation hardening (PH) stainless steel.Plasma nitriding has been used as pre-treatment to enhance adhesion and mechanical properties. Chemical and mechanical properties of DLC coatings are dependent on the hydrogen content and so on the relation between sp(3)/sp(2) bondings. The bondings and the structure of the DLC film change with temperature. In this work, a study of the thermal degradation and the evolution of the mechanical properties of DLC coatings over PH stainless steel have been carried out, including the effect of an additional nitrided layer. Nitrided and non-nitrided steel samples were subjected to the same coated in the same conditions, and they were submitted to the same thermal cycles, heating from room temperature to 600 degrees C in several steps. After each cycle, Raman spectra and surface topography measurements were performed and analyzed. Nanohardness measurements and tribological tests, using a pin-on-disc machine, were carried out to analyze variations in the friction coefficient and the wear resistance. The duplex sample, with nitriding as pre-treatment showed a better thermal stability. For duplex sample, the coating properties, such as adhesion, and friction coefficient were sustained after annealing at higher temperatures; whereas it was not the case for only coated sample. (C) 2018 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda.
  •  
39.
  • Das, Subhash, et al. (author)
  • Experimental investigation on welding of 2.25 Cr-1.0 Mo steel with regulated metal deposition and GMAW technique incorporating metal-cored wires
  • 2021
  • In: Journal of Materials Research and Technology. - : Elsevier Editora Ltda. - 2238-7854. ; 15, s. 1007-1016
  • Journal article (peer-reviewed)abstract
    • The regulated Metal Deposition (RMD) process is a variant of the gas metal arc welding process (GMAW), which was developed to effectively control the metal transfer in the short-circuiting mode. The process is fundamentally a modified short-circuit GMAW process wherein a uniform droplet deposition, making it easier for the welder to control the puddle and hence achieve an enhanced quality of welded joints. In the present study, the RMD technique has been established for the low alloy steel grade 2.25 Cr - 1.0 Mo particularly for depositing the root pass on a 10 mm thick joint. In addition to this, the RMD technique is attempted with metal-cored wires to enhance the deposition rates and hence productivity. The joint fill-up is further attempted with the GMAW technique using metal-cored wires and analysed. The weldments were subjected to post-weld heat treatment followed by mechanical and metallurgical characterization. Mechanical characterization such as tensile properties, impact properties, bend test as well as all weld tensile properties of the weld joint was evaluated and found to be acceptable. The ductile to brittle transition temperature (DBTT) testing was carried out by breaking series of impact specimen till negative temperatures. The DBTT temperature for the weld joint was found well below -30°C which indicated the strength and soundness of the welded joint. Optical microscopy and scanning electron microscopy was carried out for and favourable results were achieved in microanalysis. The study proposes the use of metal-cored wires for potential applications in the welding of high thickness joints for enhancing the overall productivity. 
  •  
40.
  • de Andrade Schwerz, Claudia, 1992, et al. (author)
  • Mechanical properties of Hastelloy X produced by laser powder bed fusion and affected by spatter redeposition
  • 2024
  • In: Journal of Materials Research and Technology. - : ELSEVIER. - 2238-7854. ; 29, s. 4200-4215
  • Journal article (peer-reviewed)abstract
    • Defects in materials manufactured via laser powder bed fusion challenge this manufacturing process' dependability and may prevent it from being comprehensively used for structural components, particularly those intended to operate under dynamic loading conditions. This study aims to investigate the effect of spatter-driven lack of fusion on the mechanical properties of Hastelloy X, with a particular focus on fatigue performance. Mechanical test specimens were manufactured in two builds with different build rates and monitored through in-situ optical tomography. The images acquired in situ were analyzed to detect spatter redeposits to predict the defect content in the gauge section. Selected specimens were measured ex-situ using X-ray computed tomography to map the defect populations. Afterward, the specimens were tensile and fatigue tested, and their performance was analyzed based on the measured and expected defect populations. It was confirmed that a higher build rate is associated with more extensive detection of spatter redeposits in optical tomography images and lack of fusion defects. The fatigue lives of specimens manufactured at higher build rates presented higher scatter but significantly higher average, despite the more critical defect population. Surprisingly, the confirmed presence of lack of fusion defects in the gauge section of test specimens did not necessarily result in a poorer fatigue performance. It was concluded that the grain refinement obtained through the increase in nominal layer thickness has a life-prolonging effect that overrides the effects of spatter-induced lack of fusion defects.
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41.
  • de Andrade Schwerz, Claudia, 1992, et al. (author)
  • Reduction of oxygen content in laser powder bed fusion process atmosphere – Effects on stochastic defect formation and mechanical properties
  • 2024
  • In: Journal of Materials Research and Technology. - : ELSEVIER. - 2238-7854. ; 30, s. 4667-4681
  • Journal article (peer-reviewed)abstract
    • Stochastic defects in materials manufactured via laser powder bed fusion (LPBF) can severely compromise mechanical performance and are challenging to predict and detect, thus motivating the development of defect mitigation strategies. Particle oxidation is a factor well-known to generate defects by disturbing melt pool dynamics. If the particles are spatters, additional disturbances increase the likelihood of defect formation. In this study, restricting oxygen content in the process atmosphere to 50 ppm is investigated to minimize stochastic spatter-induced defects and improve the mechanical properties of Hastelloy X. Specimens were manufactured under this condition at two nominal layer thicknesses, analyzed for internal defects, and mechanically tested. Contrary to expectations, reducing the oxygen content did not prevent spatter-induced defect formation; rather, it could exacerbate the formation of more numerous and larger defects. Nevertheless, this tighter control of the process atmosphere led to significant microstructural refinement, which, when combined with sparse defects, resulted in improved fatigue performance. Despite the inherent ductility of Hastelloy X, the presence of abundant defects significantly larger than the microstructural characteristic size proved detrimental to fatigue performance. Notably, the occurrence of defects exhibited considerable variation across the build area, contributing to scatter in fatigue data. However, quantitative analysis of in-situ monitoring data enabled prediction of variability in defect content and mechanical performance.
  •  
42.
  • Faramarzpour, A., et al. (author)
  • Calcite in froth flotation - a review
  • 2022
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 19, s. 1231-1241
  • Research review (peer-reviewed)abstract
    • Calcite is a semi-soluble mineral that can be considered one of the main problematic gangue phases for several different types of valuable sulfides and oxides. Since froth flotation is the main beneficiation technique for upgrading these valuable minerals, calcite flotation separation has been widely investigated. Semi solubility property of calcite makes its flotation complicated. Through the flotation process, calcium particles release cations into the pulp solution, generate similar surface properties throughout ore minerals, consume reagents, and lockdown flotation beneficiation. Over the years, to tackle this complexity, calcite reverse flotation (calcite depression) has become the main technique for its rejection; therefore, there is a gap in its direct flotation investigations. In addition, the low selectivity of the existing depressants enhanced the importance of detailed calcite surface chemistry analyses and the development of more selective depressants. These studies can use various cations and explore their interactions with calcite surface depression. Ultrasonic and leaching pretreatments have been reported to enhance calcite depression as well, although several rooms are still empty in this area. As a review article, this study generally discussed the existing challenges in detail and provided suggestions for future investigation in calcite flotation.
  •  
43.
  • Fuse, Kishan, et al. (author)
  • Dual sided composite formation in Al 6061/B4C using novel bobbin tool friction stir processing
  • 2021
  • In: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854. ; 13, s. 1709-1721
  • Journal article (peer-reviewed)abstract
    • A novel material processing approach using the bobbin tool technique called bobbin tool friction stir processing (BTFSP) was developed to simultaneously fabricate two-side composites. The feasibility of simultaneous fabrication of composites on the top and bottom sides of the workpiece using B4C reinforcement particles into Al 6061 alloy was successfully studied in the present paper. Excellent dispersion of the B4C particles obtained at the bottom side of the workpiece by this technique. The metallurgical investigation of Al 6061/B4C double side composites was carried out using optical and scanning electron microscopy. The mechanical properties include sliding wear behavior, and microhardness of the fabricated composites was studied in detail. The results indicated a more uniform distribution of B4C particles with 3 passes. The grain refinement and homogeneous distribution of the B4C significantly improved microhardness and wear properties of the fabricated composites compared to as-received Al.
  •  
44.
  • Grubova, I. Y., et al. (author)
  • Process window for electron beam melting of Ti–42Nb wt.%
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 25, s. 4457-4478
  • Journal article (peer-reviewed)abstract
    • Pre-alloyed β-phase Ti˗42Nb alloy was successfully produced for the first time by E-PBF. The study focuses on the determination of the processing parameter window by varying the beam current, beam speed, layer thickness, and line offset to achieve the defect-free manufacturing of new material with desired properties. Overall, 49 regimes were investigated. The Ti˗42Nb powder were characterized using the DSC/TG, XRD, and SEM/EDX analyses to evaluate its suitability for E-PBF manufacturing. The alloys with the best-built quality fall into the narrow zone between the line energies of 0.30 and 0.34 J/mm. The predicted optimal process parameters were I = 4 mA, v = 700–800 mm/s, h = 100 μm, U = 60 kV, and t = 100 μm. Detailed microstructural characterization was carried out to gain insights into the fundamental mechanisms that govern the behavior of the studied alloys. TEM identified the α'' martensitic phase nucleation occurred preferentially at the β grain boundaries. Un-melted ellipsoidal NbC (∼10 μm) particles were detected with no preferential segregation sites. EBSD revealed coarse microstructures and <001> fiber texture, as well as epitaxial grain growth of columnar grains of about 300 μm. The optimal regime demonstrated a texture composed of a high amount of low aspect ratio grains (50%), which yielded a microindentation hardness of 3.0 GPa and a low elastic modulus of 68 GPa. Hence, these results provide opportunities to design novel alloys to be of interest for biomedical applications. Moreover, this study extends the scope of AM by establishing the process parameter window that yields a material with favorable mechanical properties.
  •  
45.
  • Hanif, Imran, et al. (author)
  • High-temperature corrosion of weld overlay coating/bulk FeCrAl exposed in O2 + H2O + KCl(s) at 600 °C – A microstructural investigation
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier Editora Ltda. - 2238-7854. ; 25, s. 7008-7023
  • Journal article (peer-reviewed)abstract
    • This work investigates the impact of high-temperature corrosion behavior of the newly developed FeCrAl alloy Kanthal® EF101 bulk material and weld overlay coating in the presence of KCl(g)/KCl(s) at 600 °C. The oxide scale formed within the secondary corrosion regime after exposure and the impact of alloy microstructure on corrosion behavior was investigated using scanning transmission electron microscopy. The findings indicated the key microstructural differences is the alloy grain size which influences the formation of a protective scale. In addition, It is indicated that coating exhibited inferior performance than the bulk material, primarily attributed to the microstructural differences. © 2023 The Author(s)
  •  
46.
  • Harwani, Deepika, et al. (author)
  • Developing superplasticity in magnesium alloys with the help of friction stir processing and its variants : A review
  • 2021
  • In: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 12, s. 2055-2075
  • Journal article (peer-reviewed)abstract
    • Friction stir processing (FSP), an adaption of the solid-state joining process friction stir welding (FSW), is now a widely recognized severe plastic deformation (SPD) technique. It induces microstructural refinement in the metallic materials which enhances their formability and other mechanical properties. Dynamic recrystallization occurs during the stirring phase which leads to reduction in the grain size and texture modification. Breaking up of the intermetallics and precipitates with their homogeneous distribution in the matrix is also accompanied. This further improves the material's ability to attain maximum ductility during plastic deformation at higher temperatures, resulting in very large uniform elongations (>200%) termed as ‘superplasticity’. Optimization of FSP parameters activates superplastic behaviour in different magnesium alloys at low temperatures and high strain rates. It has become the focal point of the recent researches owing to its huge potential in the light-weight structural applications. In addition to the essential aspects of superplasticity, this article highlights the major explorations in the area of superplasticity of magnesium alloys using FSP method and it's recently developed variants.
  •  
47.
  • He, Junjing, et al. (author)
  • Application of soft constrained machine learning algorithms for creep rupture prediction of an austenitic heat resistant steel Sanicro 25
  • 2023
  • In: JOURNAL OF MATERIALS RESEARCH AND TECHNOLOGY-JMR&T. - : Elsevier BV. - 2238-7854. ; 22, s. 923-937
  • Journal article (peer-reviewed)abstract
    • Creep rupture extrapolation is crucial for high-temperature materials served in power plants. Many analytical models can be used for creep rupture analysis, and fundamental models are also available. Machine learning is also an alternative. However, unphysical prediction curves occur readily in common machine learning algorithms, where one must manipulate the best results or ignore the less satisfactory ones. Using just high regression coefficients and low errors is not enough to obtain high accuracy of the methods. Never-theless, five soft constrained machine learning algorithms (SCMLAs), where soft con-straints, stability analysis by culling long-time or low-stress data, extrapolation from short to long times, and errors of solutions and algorithms are considered, are used for creep rupture prediction in this work. The models can generate reasonable results for fitting all data, extrapolating from short to long times, and stability analysis for Sanicro 25 after a number of tests. The errors of solutions for all the analyses are in a quite reasonable range, including extrapolation and stability analysis. The average relative standard deviation of the five SCMLAs is less than 2.5% at three times the maximum experimental creep rupture time. Creep rupture strength of the austenitic stainless steel Sanicro 25 can be predicted quantitatively by taking the average predicted stresses of the five SCMLAs. The method can also be used for other high-temperature alloys with similar creep degradation mechanisms.
  •  
48.
  • He, Junjing, et al. (author)
  • Evaluating creep rupture life in austenitic and martensitic steels with soft-constrained machine learning
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854. ; 27, s. 5165-5176
  • Journal article (peer-reviewed)abstract
    • Machine learning is extensively utilized for predicting creep rupture of high-temperature steels. Recently, five soft-constrained machine learning algorithms (SCMLAs) have been developed to enhance the extrapolation capabilities of machine learning. These SCMLAs were applied to the austenitic steel Sanicro 25, showing their potential. To improve SCMLAs, this study has introduced new guidelines that address temperature culling within the input range and temperature extrapolation beyond the input range. Leveraging these guidelines, the SCMLAs were extended to various austenitic and martensitic stainless steels. The predicted results of TP316H, the data of which is representative of austenitic stainless steels, were validated through error estimates. Furthermore, notable agreement has been reached for temperature culling and temperature extrapolation, as demonstrated for TP91 and TP92 martensitic steels. The effects of single casts and the temperature dependence of the predictions have been analyzed for the studied materials. Consistent results can be readily achieved through systematic evaluations of SCMLAs for extrapolating up to 300,000 h or three times the maximum experimental rupture time for the studied materials. It is demonstrated that SCMLAs can provide reliable creep rupture life prediction across various high-temperature materials.
  •  
49.
  • He, Junjing, et al. (author)
  • The role of strength distributions for premature creep failure
  • 2023
  • In: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854. ; 25, s. 3444-3457
  • Journal article (peer-reviewed)abstract
    • Premature and unexpected creep damage is a significant concern in high-temperature engineering. Identifying outliers in creep rupture data is essential for assessing the risk of premature creep failure. This study proposes a new method to evaluate premature creep failure using log-logistic distribution fit of prediction errors and outlier positions. Fitting results for seven different alloys were obtained from extrapolation procedures using soft-constrained machine learning algorithms (SCMLAs) and constrained time-temperature parameters (TTPs) based on prior research. A comprehensive statistical analysis was conducted for all materials. The log-logistic distribution was validated as a suitable method for fitting prediction error distributions. Regression plots demonstrate effective residual balance and accurate outlier capture. The best fitting methods were identified based on the width of the distributions. Outlier positions were used to evaluate the probability of premature creep failure quantitatively. For example, a 0.5% probability of observing creep rupture strengths that are approximately 50% lower than the standardized creep stress was found for TP316H, T321H, and high Cr steels SUH616B. These findings offer valuable insights for estimating premature creep failure in materials.
  •  
50.
  • Hosseini, Vahid, 1987-, et al. (author)
  • Precipitation kinetics of Cu-rich particles in super duplex stainless steels
  • 2021
  • In: Journal of Materials Research and Technology. - : Elsevier BV. - 2238-7854. ; 15, s. 3951-3964
  • Journal article (peer-reviewed)abstract
    • Complex precipitation behavior of Cu-rich particles (CRPs) was investigated and simulated in continuously cooled and quench-aged super duplex stainless steel. Atom probe tomography (APT) and scanning electron microscopy showed that slow cooling resulted in nonuniform multimodal CRP precipitation and spinodal decomposition, while in the fast cooled and quench-aged conditions, more uniform precipitation of CRPs with no visible spinodal decomposition was found. Depletion of Cu, Ni, and Mn was observed in the ferrite next to the CRPs during growth, but not during dissolution. Some evidence of Ostwald ripening was seen after slow cooling, but in the quench-aged condition, particle coalescence was observed. Large CRPs disappeared next to a ferrite–austenite phase boundary after slow cooling when Cu was depleted due to the diffusion to austenite as also predicted by moving boundary Dictra simulation. Comparing Cu depleted areas next to CRPs analyzed by APT and moving boundary Dictra simulation of CRP–ferrite showed that the effective Cu diffusion coefficient during the early-stage precipitation was about 300 times higher than the Cu diffusion coefficient in ferrite at 475 °C. Using the effective diffusion coefficient and a size-dependent interfacial energy equation, CRP size distribution was successfully predicted by the Langer–Schwartz model implemented in Thermo-Calc Prisma. Applying a short aging time and continuous cooling increased the hardness and decreased the toughness values compared to the solution annealed condition. A nonuniform distribution of Cu in ferrite, the duplex structure, and partitioning of alloying elements among different phases are factors making CRP precipitation in duplex stainless steels complex.
  •  
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