| 1. |
- Andersson, Joel Håkan, 1981, et al.
(författare)
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Solidification of alloy 718, ati 718Plus® and waspaloy
- 2014
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Ingår i: 8th International Symposium on Superalloy 718 and Derivatives 2014. - Hoboken, NJ, USA : John Wiley & Sons, Inc.. - 9781634396424 ; , s. 181-192
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Konferensbidrag (refereegranskat)abstract
- Alloy 718, ATI 718Plus® and Waspaloy have been investigated in terms of what their respective solidification process reveals. Differential thermal analysis was used to approach the task together with secondary electron and back scattered electron detectors equipped with an energy dispersive X-ray spectroscopy detector. These experimental methods were used to construct pseudo binary phase diagrams that could aid in explaining solidification as well as liquation mechanisms in processes such as welding and casting. Furthermore, it was seen that Waspaloy has the smallest solidification range, followed by Alloy 718, and finally ATI 718Plus® possessing the largest solidification interval in comparison.
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| 2. |
- Donnadieu, P., et al.
(författare)
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Deformation at ambient and high temperature of in situ Laves phases-ferrite composites
- 2014
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Ingår i: Science and Technology of Advanced Materials. - : Informa UK Limited. - 1468-6996 .- 1878-5514. ; 15:3
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical behavior of a Fe80Zr10Cr10 alloy has been studied at ambient and high temperature. This Fe 80Zr10Cr10 alloy, whoose microstructure is formed by alternate lamellae of Laves phase and ferrite, constitutes a very simple example of an in situ CMA phase composite. The role of the Laves phase type was investigated in a previous study while the present work focuses on the influence of the microstructure length scale owing to a series of alloys cast at different cooling rates that display microstructures with Laves phase lamellae width ranging from ∼50 nm to ∼150 nm. Room temperature compression tests have revealed a very high strength (up to 2 GPa) combined with a very high ductility (up to 35%). Both strength and ductility increase with reduction of the lamella width. High temperature compression tests have shown that a high strength (900 MPa) is maintained up to 873 K. Microstructural study of the deformed samples suggests that the confinement of dislocations in the ferrite lamellae is responsible for strengthening at both ambient and high temperature. The microstructure scale in addition to CMA phase structural features stands then as a key parameter for optimization of mechanical properties of CMA in situ composites. © 2014 National Institute for Materials Science.
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| 3. |
- Gyhlesten Back, Jessica, et al.
(författare)
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Microstructure analysis of martensitic low alloy carbon steel samples subjected to deformation dilatometry
- 2019
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Ingår i: Materials Characterization. - : Elsevier. - 1044-5803 .- 1873-4189. ; 157
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Tidskriftsartikel (refereegranskat)abstract
- Low alloy martensitic steels are commonly used in structural and wear resistant applications due to their excellent mechanical properties and abrasion resistance. Martensite phase is generally achieved by rapid cooling, and prior deformation in the austenite region also affects the martensite transformation. It is important to understand the martensite transformation when there is deformation above Ae3. Deformation and quenching simulations have been performed using dilatometry on a low alloy carbon steel. The aim was to determine the influence of deformation above Ae3 (prior deformation) on, firstly, the austenite grain size and shape, and secondly, the martensitic microstructure and variant selection. In addition, the hardness of the martensitic structure due to prior deformation has been investigated. The experimental results obtained from electron backscatter diffraction and microhardness tests on the deformation dilatometry test samples were analysed. The orientation relationship Kurdjumov-Sachs has been used to analyse the martensitic variants. The results revealed a deeper understanding of prior austenite grain structure's effect on the martensitic transformation kinetics and its morphology. The martensite laths' misorientation interval 15–48° were used to visualise the prior austenite grain size. The martensitic lath structure is more refined due to increased prior deformation. Shorter martensite formation time promotes a single dominating packet within the prior austenite grain.
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| 4. |
- Habainy, Jemila, et al.
(författare)
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Formation of oxide layers on tungsten at low oxygen partial pressures
- 2018
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 506:SI, s. 26-34
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Tidskriftsartikel (refereegranskat)abstract
- This work focuses on the oxidation of tungsten in inert gas atmospheres containing oxygen and moisture. It is particularly relevant for the European Spallation Source where the tungsten target is cooled by purified helium gas and the 5 MW proton beam can raise the maximum target temperature beyond the threshold for oxidation. Tungsten discs were oxidized isothermally at 400° to 900 °C for 2 h in pure helium and helium mixed with oxygen and water vapor, with varying partial pressures up to 500 Pa. Tungsten was oxidized even with a small amount of oxygen (≤5 ppm) present in industrially pure helium. Non-isothermal oxidation of tungsten foils was carried out in water vapor (∼100 Pa), in situ in an environmental scanning electron microscope. On specimens oxidized in inert gas containing water vapor (2 h, pH2O" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 14.4px; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">pH2O ∼790 Pa), Auger electron spectroscopy studies confirmed the presence of a thin oxide layer (40 nm) at 400 °C. At 500 °C the oxide layer was 10 times thicker. A dark, thin and adherent oxide layer was observed below 600 °C. Above this temperature, the growth rate increased substantially and the oxide layer was greenish, thick and porous. Oxide layers with varying stoichiometry were observed, ranging from WO3 at the surface to WO2 at the metal-oxide interface. For comparison, oxidation of tungsten alloysin He-5%O2 was studied. The implications of this work on the design and operation of the helium loop for cooling the target are discussed.
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| 5. |
- Habainy, J., et al.
(författare)
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Study of heavy ion beam induced damage in tungsten for high power target applications
- 2019
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 439, s. 7-16
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Tidskriftsartikel (refereegranskat)abstract
- The spallation material at ESS is pure tungsten, which is cooled by gaseous helium flow. To study the behaviour of tungsten under dynamic beam conditions at ESS, pure tungsten specimens have been irradiated at the M3-beamline of the UNILAC facility at GSI Helmholtz Centre for Heavy Ion Research. Tungsten specimens of two thicknesses, 26 μm and 3 mm, were exposed to pulsed uranium and gold ion beams for fluences up to 7.5 · 1013 ions·cm−2 at 4.8 MeV/nucleon. Nanoindentation tests were performed on the cross section of the irradiated 3 mm sample, and microhardness was measured on the top surface. The measured data are compared with the calculated damage values, and a correlation between the radiation induced damage and the observed mechanical property is presented. Thermal diffusivities of foil samples irradiated up to four different fluences were measured with a Laser Flash Apparatus (LFA). The observed changes in the mechanical and thermal properties of irradiated tungsten were used to estimate the changes of operational temperature and mechanical stresses in the ESS target material with the progress of radiation damage, using coupled thermal and mechanical simulations. From the pulsed beam induced dynamic oscillations of thin tungsten specimens, information on fatigue properties of tungsten under irradiation was drawn. In addition to pure tungsten, oxidised tungsten samples were irradiated. This is to investigate the stability of the adhesive oxide layer under pulsed beam conditions, which would be formed due to oxygen impurities in the helium cooling loop. The irradiated oxide scale was examined using Auger Electron Spectroscopy (AES) and Scanning Electron Microscopy (SEM).
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| 6. |
- Heinrichs, Jannica, et al.
(författare)
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Exploring the tribochemical wear and material transfer caused by Cu15Zn alloys on shearing tools
- 2024
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Ingår i: Wear. - : Elsevier. - 0043-1648 .- 1873-2577. ; 542
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Tidskriftsartikel (refereegranskat)abstract
- Cemented carbide tools are extensively used in the zipper industry, including shearing of a pre-formed Cu15Zn wire into individual zipper elements. Although the work material is significantly softer than the tool, wear is the life limiting factor for the tools and is considered to be of tribochemical nature. So far it has not been explained, however, it is known that the wear rate of uncoated, as well as CrC and CrN coated, cemented carbide increases dramatically when Zn is omitted from the Cu alloy. In this paper, worn tool surfaces, including any transferred material, were studied to investigate the tribochemical wear mechanism in detail. Material transfer occurred onto all tool surfaces. Cu and Zn were separated on the sub-micron scale, and preferential transfer of one of the constituents was observed. This is reflected in the outermost surface of the sheared element, which shows a homogeneous composition elsewhere. Oxidation was observed of all tool surfaces, which indicates elements of oxidative wear. Further, any Zn transferred to the tool surfaces was oxidized. Thus, it is suggested that the presence of Zn reduces the oxygen available and consequently reduces the oxidation rate of the tool surfaces, leading to the protective effect previously observed. © 2024 The Authors
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| 7. |
- Hoier, Philipp, 1988, et al.
(författare)
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Tool wear by dissolution during machining of alloy 718 and Waspaloy: a comparative study using diffusion couples
- 2020
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Ingår i: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 106:3-4, s. 1431-1440
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Tidskriftsartikel (refereegranskat)abstract
- The wear of metal cutting tools is known to take place by the combined and simultaneous effects of several wear mechanisms. Knowledge of the relative contribution of the individual wear mechanisms is required to understand and predict the tool wear during cutting different workpiece materials and alloys. It has been shown previously that machining two heat resistant superalloys, alloy 718 and Waspaloy, leads to distinctively different tool wears. Even though the subject has been addressed in various studies, there are still open questions regarding the underlying reasons for the differing tool wear rates. In particular, the relative contributions of diffusion/dissolution when machining the two alloys have not been addressed so far. Therefore, a qualitative comparison of the chemical interaction between the tool material and the two superalloys was made by using diffusion couple tests. The aim was to mimic the high temperatures and intimate contact between workpiece and tool material at the tool rake and flank faces during cutting under controlled and static conditions. The obtained results suggest that it is unlikely that differences in flank wear rate when machining the two superalloys are caused by significantly varying magnitudes of tool atoms dissolving into the respective workpiece. Analysis of the tool/superalloy interfaces in the diffusion couples revealed diffusion-affected zones of similar size for both tested superalloys. Increasing test temperature led to enhanced interdiffusion which suggests an increase in tool wear by diffusion/dissolution for higher cutting temperature. For alloy 718, the higher test temperature also led to depletion of carbon together with formation of tungsten within the tool in close vicinity to the interface with the superalloy.
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| 8. |
- Jayamani, Jayaraj, et al.
(författare)
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Electrochemical and passivation behavior of a corrosion-resistant WC-Ni (W) cemented carbide in synthetic mine water
- 2023
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Ingår i: International journal of refractory metals & hard materials. - : Elsevier BV. - 0263-4368. ; 114
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Tidskriftsartikel (refereegranskat)abstract
- Two different grades, WC-20 vol.% Ni and WC-20 vol.% Co cemented carbides, respectively were systematically investigated concerning their microstructure, binder composition, and corrosion behavior. SEM-EBSD analysis verified that both grades have similar WC grain sizes (0.9-1.1 mu m). AES analysis confirmed that the binder phase of the respective grade is an alloy of Ni-W and Co-W and that the concentration of W in the Ni-and Co-binder is 21 and 10 at. %, respectively. In synthetic mine water (SMW), the EIS behavior of WC-Ni(W) at the open circuit potential (OCP) conditions was studied for different exposure periods (up to 120 h). The EIS data fitting estimates low capacitance and high charge transfer resistance (Rct) values, which indicate that the passive film formed on WC-Ni(W) is thin and exhibits high corrosion resistance. At the OCP and potentiostatic-passive conditions, SEM investigations confirm the uncorroded microstructure of the WC-Ni(W). The AR-XPS studies confirmed the formation of an extremely thin (0.25 nm) WO3 passive film is responsible for the high corrosion resistance of WC-Ni(W), at OCP conditions. However, above the transpassive potential, the microstructure instability of WC-Ni(W) was observed, i.e., corroded morphology of both WC grains and Ni(W) binder. The electrochemical parameters, Rct, corrosion current density, and charge density values, confirmed that the WC-Ni(W) is a far better alternative than the WC-Co(W) for application in SMW.
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| 9. |
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| 10. |
- Lin, Zeyu, 1991-, et al.
(författare)
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Influence of Electron Beam Powder Bed Fusion Process Parameters on Transformation Temperatures and Pseudoelasticity of Shape Memory Nickel Titanium
- 2023
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Ingår i: Advanced Engineering Materials. - : John Wiley & Sons. - 1438-1656 .- 1527-2648. ; 25:12
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Tidskriftsartikel (refereegranskat)abstract
- Electron beam powder bed fusion (PBF-EB) is used to manufacture dense nickel titanium parts using various parameter sets, including the beam current, scan speed, and postcooling condition. The density of manufactured NiTi parts is investigated in relation to the linear energy input. The results imply that the part density increases with increasing linear energy density to over 98% of the bulk density. With a constant energy input, a combination of low power and low scan speed leads to denser parts. This is attributed to lower electrostatic repulsive forces from lower number density of the impacting electrons. After manufacturing, the densest parts with distinct parameter sets are categorized into three groups: 1) high power with high scan speed and vacuum slow cooling, 2) low power with low scan speed and vacuum slow cooling, and 3) low power with low scan speed and medium cooling rate in helium gas. Among these, a faster cooling rate suppresses phase transformation temperatures, while vacuum cooling combinations do not affect the phase transformation temperatures significantly. Herein, all the printed parts exhibit almost 8% pseudoelasticity regardless of the process parameters, while the parts cooled in helium have a higher energy dissipation efficiency (1 − η), which implies faster damping of oscillations. © 2023 The Authors. Advanced Engineering Materials published by Wiley-VCH GmbH.
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| 11. |
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| 12. |
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| 13. |
- Nath, Deo, et al.
(författare)
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Structure and properties of Al–Ni PM composites
- 2004
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Ingår i: Powder Metallurgy. - : Taylor & Francis. - 0032-5899 .- 1743-2901. ; 47:3, s. 247-252
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Tidskriftsartikel (refereegranskat)abstract
- Al–Ni powder mixtures containing 2, 4, 6 and 8 wt-% nickel were compacted at 125, 250, 375 and 500 MPa and sintered at 620, 630 and 640°C in a nitrogen atmosphere. The sintered density, sintered hardness and strength of composites thus produced were determined as a function of compaction pressure and sintering temperature. Wear rates of the composites were evaluated as a function of applied load and sliding velocity. Optical and scanning electron microscopy were used to reveal the morphology of powder and microstructures of green and sintered compacts. X-ray diffraction studies of the sintered compacts were made to confirm the phases formed on sintering. Sintered density, sintered hardness and strength increased with an increase in compaction pressure and nickel content. X-ray diffraction indicated the presence of Al3Ni phase in the sintered alloy. The wear rate of the sintered Al–Ni PM composite was found to increase with increasing load and decrease with increasing nickel content.
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| 14. |
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| 15. |
- Olsson, Mikael, et al.
(författare)
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Scratch testing of cemented carbides - Influence of Co binder phase and WC grain size on surface deformation and degradation mechanisms
- 2018
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Ingår i: Proceedings of The 18th Nordic Symposium on Tribology - Nordtrib 2018. - Uppsala : Uppsala University.
-
Konferensbidrag (refereegranskat)abstract
- In the present study, the microstructural response of some commercial cemented carbide grades during scratchinghas been analyzed and evaluated by a number of post-test characterization techniques. The influence of Co binder phase content and WC grain size on the deformation and degradation on a WC grain size scale and on a composite scaleare evaluated. The results clearly illustrate the complexity of deformation, degradation and wear of cemented carbide and the dynamics of the diamond stylus / cemented carbide contact during the scratching event. For all cementedcarbide grades the microstructure has a strong impact on the observed degradation mechanisms and the resistance to deformation and degradation was found to increase with decreasing Co content and decreasing WC grain size.
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| 16. |
- Olsson, Mikael, et al.
(författare)
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Thin hard CVD and PVD coatings and their potential in steel wire drawing applications
- 2018
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Ingår i: Proceedings of The 18th Nordic Symposium on Tribology - NORDTRIB 2018. - Uppsala : Uppsala University.
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Konferensbidrag (refereegranskat)abstract
- In the present work, the potential of using thin hard CVD and PVD coatings in order to improve the performance of cemented carbide steel wire drawing nibs is evaluated. Coating materials include some state-of-the-art CVD and PVD coatings and pre- and post-coating treatments were used to improve the surface topography of the coated functional surfaces. The tribological performance of the coatings has been evaluated by sliding wear tests and wire drawing experiments under well controlled conditions. Post-test characterization of the coated nibs using 3D optical surface profilometry, scanning electron microscopy and energy dispersive X-ray spectroscopy illustrates the pros and cons of the two deposition techniques but also that the coatings have a potential to improve the performance of cemented carbide nibs in steel wire drawing applications.
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| 17. |
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| 18. |
- Prashanth, K.G., et al.
(författare)
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Microstructure and mechanical properties of Al-12Si produced by selective laser melting: Effect of heat treatment
- 2014
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Ingår i: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - : Elsevier BV. - 0921-5093 .- 1873-4936. ; 590, s. 153-160
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Tidskriftsartikel (refereegranskat)abstract
- Al-12Si specimens are produced by selective laser melting (SLM) from gas atomized powders. An extremely fine cellular structure is observed with residual free Si along the cellular boundaries. Room temperature tensile tests reveal a remarkable mechanical behavior: the samples show yield and tensile strengths of about 260. MPa and 380. MPa, respectively, along with fracture strain of ~3%. The effect of annealing on microstructure and related tensile properties is examined and the results demonstrate that the mechanical behavior of the Al-12Si SLM samples can be tuned within a wide range of strength and ductility through proper annealing treatment.
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| 19. |
- Prashanth, Konda Gokuldoss, et al.
(författare)
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Powder metallurgy of high-strength Al90.4Y4.4Ni4.3Co0.9 gas-atomized powder
- 2012
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Ingår i: 13th International Conference on Aluminum Alloys (ICAA13). - Cham : Springer, Cham. ; , s. 1017-1022
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Konferensbidrag (refereegranskat)abstract
- Al90.4Y4.4Ni4.3Co0.9 gas-atomized powder was hot pressed (HP) to produce highly dense bulk samples through combined devitrification and consolidation. The microstructure of the as-atomized powder is a mixture of amorphous phase with nanocrystalline fcc Al, whereas the consolidated samples consists of fcc Al and a series of intermetallic phases with or without residual amorphous phase depending on the hot pressing temperature (673 or 723 K). The HP samples exhibit a remarkable high strength of ~ 925 MPa (HP at 673 K) and ~ 820 MPa (HP at 723 K) combined with a plastic strain ranging between 14 and 30%. The reduction in strength for the sample HP at 723 K is linked to the complete crystallization of the powder with no residual amorphous phase.
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| 20. |
- Prashanth, K.G., et al.
(författare)
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Structural and Mechanical Characterization of Zr 58.5Ti 8.2Cu 14.2Ni 11.4Al 7.7 Bulk Metallic Glass
- 2012
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Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 5:1, s. 1-11
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Tidskriftsartikel (refereegranskat)abstract
- Thermal stability, structure and mechanical properties of the multi-component Zr 58.5Ti 8.2Cu 14.2Ni 11.4Al 7.7 bulk metallic glass have been studied in detail. The glassy material displays good thermal stability against crystallization and a fairly large supercooled liquid region of 52 K. During heating, the alloy transforms into a metastable icosahedral quasicrystalline phase in the first stage of crystallization. At high temperatures, the quasicrystalline phase undergoes a transformation to form tetragonal and cubic NiZr 2-type phases. Room-temperature compression tests of the as-cast sample show good mechanical properties, namely, high compressive strength of about 1,630 MPa and fracture strain of 3.3%. This is combined with a density of 6.32 g/cm 3 and values of Poisson's ratio and Young's modulus of 0.377 and 77 GPa, respectively. The mechanical properties of the glass can be further improved by cold rolling. The compressive strength rises to 1,780 MPa and the fracture strain increases to 8.3% for the material cold-rolled to a diameter reduction of 10%.
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| 21. |
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| 22. |
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| 23. |
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| 24. |
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| 25. |
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| 26. |
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| 27. |
- Scudino, Sergio, et al.
(författare)
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High-strength Al87Ni8La5 bulk alloy produced by spark plasma sintering of gas atomized powders
- 2009
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Ingår i: Journal of Materials Research. - : Cambridge University Press. - 0884-2914 .- 2044-5326. ; 24:9, s. 2909-2916
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Tidskriftsartikel (refereegranskat)abstract
- In situ devitrification and consolidation of gas atomized Al87Ni8La5 glassy powders into highly dense bulk specimens was carried out by spark plasma sintering. Room temperature compression tests of the consolidated bulk material reveal remarkable mechanical properties, namely, high compression strength of 930 MPa combined with plastic strain exceeding 25%. These findings demonstrate that the combined devitrification and consolidation of glassy precursors by spark plasma sintering is a suitable method for the production of Al-based materials characterized by high strength and considerable plastic deformation.
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| 28. |
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| 29. |
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| 30. |
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| 31. |
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| 32. |
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| 33. |
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| 34. |
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| 35. |
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| 36. |
- Scudino, Sergio, et al.
(författare)
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Solid-state processing of Al-Mg alloys
- 2009
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Ingår i: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 144:1
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Tidskriftsartikel (refereegranskat)
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| 37. |
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| 38. |
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| 39. |
- Sokkalingam, Rathinavelu, et al.
(författare)
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Microstructure and properties of in-situ high entropy alloy/tungsten carbide composites by mechanical alloying.
- 2020
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Ingår i: Material Design & Processing Communications. - : John Wiley & Sons. - 2577-6576. ; n/a:n/a, s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Al0.1CoCrFeNi-high entropy alloy (HEA) /tungsten carbide (WC)metal matrix composite was successfully prepared by mechanical alloying and subsequent spark plasma sintering. The different volume fraction of WC was distributed evenly by varying the powder milling parameters from gentle milling (~1.37% WC) and intensive milling (~14.27% WC). Sintering of gently milled powder has resulted in the evolution of three-phased microstructure: α-fcc and Cr- rich σ-phase with some WC-phase distributed in the HEA matrix. On the other hand, the sintering of intensively milled powder has resulted in a two-phased microstructure: α-fcc phase with even and dense distribution of WC-phased particles without any Cr- rich σ-phase. The absence of σ-phase is attributed to a complete alloying of Cr in the HEA matrix. Microhardness analysis and compression test indicate that a ~ 13% difference in WC fraction has resulted in an enhancement in hardness (46%) and compressive strength (~ 500 MPa).
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| 40. |
- Sokkalingam, Rathinavelu, et al.
(författare)
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Powder metallurgy of Al0.1CoCrFeNi high-entropy alloy
- 2020
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Ingår i: Journal of Materials Research. - : Springer Science and Business Media LLC. - 0884-2914 .- 2044-5326. ; 35:21, s. 2835-2847
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Tidskriftsartikel (refereegranskat)abstract
- Al0.1CoCrFeNi high-entropy alloy (HEA) was synthesized successfully from elemental powders by mechanical alloying (MA) and subsequent consolidation by spark plasma sintering (SPS). The alloying behavior, microstructure, and mechanical properties of the HEA were assessed using X-ray diffraction, electron microscope, hardness, and compression tests. MA of the elemental powders for 8 h has resulted in a two-phased microstructure: α-fcc and β-bcc phases. On the other hand, the consolidated bulk Al0.1CoCrFeNi-HEA sample reveals the presence of α-fcc and Cr23C6 phases. The metastable β-bcc transforms into a stable α-fcc during the SPS process due to the supply of thermal energy. The hardness of the consolidated bulk HEA samples is found to be 370 ± 50 HV0.5, and the yield and ultimate compressive strengths are found to be 1420 and 1600 MPa, respectively. Such high strength in the Al0.1CoCrFeNi HEA is attributed to the grain refinement strengthening.
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| 41. |
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| 42. |
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| 43. |
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| 44. |
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| 45. |
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| 46. |
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| 47. |
- Surreddi, Kumar Babu, 1977-, et al.
(författare)
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Characterization of surface degradation and wear damage Of cemented carbide in rock drilling
- 2018
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Ingår i: The 18th Nordic Symposium on Tribology – NORDTRIB 2018.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this work, worn top hammer drill bit buttons after underground drifting in Granodiorite are analysed using scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and electron backscatter diffraction (EBSD) to understand the dominant surface failure and wear mechanisms on the flank wear land region, i.e. the outer side of the gauge row cemented carbide buttons. SEM shows that the worn surface of the flank wear land is partly covered with islands of a thin rock material transfer layer and that the exposed cemented carbide show deformed, cracked and fragmented WC grains. AES gives that the transferred rock material is mainly located on the surface but may penetrate into cemented carbide microstructure to a depth of 1-2 WC grain diameters. Finally, EBSD reveals that the deformation of the cemented carbide in the flank wear land region is located to a thin zone, about ~10 μm in depth.
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| 48. |
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| 49. |
- Surreddi, Kumar Babu, 1977, et al.
(författare)
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Effect of Heat Treatment on Chip Formation in a Case Hardening Steel
- 2013
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Ingår i: Journal of Materials and Chemical Engineering. - 2310-063X .- 2310-0621. ; 1:1, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- In manufacturing industry, variations in machinability are regularly observed when producing the same part out of different material batches of a case hardening steel. Some batches result in variations in chip breakability which leads to a non-robust production process with unforeseen stops of automatic machining process. The aim of the present study is to investigate the influence of the microstructure on chip formation in case hardening steel. Different microstructures were produced from the same batch of material by varying heat treatment. Chips were collected after machining at different feed rates and depths of cut. The cross sections of the chips have been analyzed with respect to overall deformation pattern, mean thickness, and degree of segmentation. Also, the influence of manganese sulfide on machinability has been investigated. The microstructural investigation of the chips has shown that there is a clear difference in the deformation behavior between a case hardening steel with larger and smaller pearlite nodular structure. Chips from the material with larger pearlite nodular size and lower amount of pro-eutectoid ferrite are by far more segmented as compared to chips from materials with smaller pearlite nodular size.
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| 50. |
- Surreddi, Kumar Babu, 1977-, et al.
(författare)
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In-situ micro-tensile testing of additive manufactured maraging steels in the SEM : Influence of build orientation, thickness and roughness on the resulting mechanical properties
- 2018
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Ingår i: La Metallurgia Italiana. - : ASSOC ITALIANA METALLURGIA. - 0026-0843. ; :3, s. 27-33
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Tidskriftsartikel (refereegranskat)abstract
- Selective laser melting (SLM) is frequently used additive manufacturing technique capable of producing various complex parts including thin-wall sections. However the surface roughness is a limiting factor in thin sections produced by SLM process when strength is the main criterion. In this study, the influence of build orientation, thickness and roughness on the resulting mechanical properties of as-built test samples was investigated. Various thin sheets of EN 1.2709 maraging steel built in horizontal and vertical orientations produced by SLM were investigated using in-situ micro-tensile testing in a scanning electron microscope. The mechanical strength and deformation mechanisms were analyzed and explained based on thickness and build orientation. Increased ductility was observed in thicker samples as well as in the horizontal build samples. The results illustrate the potential of the in-situ test technique and aspects important to consider in design guidelines for thin AM structures.
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