| 1. |
- Andersson, K., et al.
(författare)
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Failure Investigation of an Airline Engine Failure During Take Off
- 2013
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Ingår i: Praktische Metallographie/Practical Metallography. - : Walter de Gruyter GmbH. - 0032-678X. ; 50:12, s. 821-830
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Tidskriftsartikel (refereegranskat)abstract
- An Iran Airlines CF6-8002A2F engine had a turbine failure during takeoff from the Arlanda airport in Sweden, in January 2010. Failure investigation of the engine was performed by Lufthansa Technik AG (LHT). The Swedish Accident Investigation Board (SHK) requested a second opinion of the available High Pressure Turbine (HPT) Diffuser Aft Seal hardware, received from LHT, and because of GKN Aerospace Sweden's extensive experience as Original Equipment Manufacturer (OEM) of Swedish fighter engines this second failure analysis work was performed by GKN. The failure investigation of the Diffuser Aft Seal pieces and fragments received from LHT revealed no fractures or fatigue cracks which are believed to be evidences of the primary cause to the failure. However, a secondary fatigue crack was found in an aft tooth fragment from the Diffuser Aft Seal. This tooth fragment has also a machining step on the forward surface, between a repair weld and the original tooth, with a geometry which gives a stress concentration factor of about 2.5 for radial and bending stresses in this area. This machining step may have contributed to initiate a fatigue crack in the seal tooth.
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| 2. |
- Andersson, Thorvald, 1946, et al.
(författare)
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Preparation and characterization of the ITO surface and the Al/Alq3/ITO heterostructure for OLEDs
- 2007
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Ingår i: Materials Science and Engineering B. ; 145, s. 48-56
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Tidskriftsartikel (refereegranskat)abstract
- We have made a detailed investigation of structure and chemical composition in thermally grown Al/Alq3/ITO layer structures intended for light emission. The different parts of the structure were studied by X-ray photoelectron spectroscopy and microscopical techniques. The indium tinoxide substrate surface consisted of grains 20–50 nm in diameter and about 5 nm in height, which also showed molecular sized sub-grain features. Due to the ambient the ITO surface was covered by a 1 nm thick hydrocarbon layer which serves as the actual surface on which an organic layer is deposited for device fabrication. A structural model for the indium tin oxide surface, on which the small molecules were deposited, was suggested. The substrate surface was treated to study the relation between the surface manipulation and the hole injection barrier. Such surface modification significantly improved the performance of a single layer Alq3 organic light emitting diode. Depth profiling of the complete structure, revealed that the aluminium contact mostly consisted of aluminium oxide with some intermixing of carbon. Further, variations of the atomic concentration of the elements In, Sn, C and O and a minor shift in their binding energies were measured. Both, position and shape of the oxygen and indium peaks were changed during argon ion sputtering. At the Alq3/ITO interface an indium–oxygen compound, different from that on the original surface, hadformed. Various effects of the compositional findings on the light emission are discussed.
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| 3. |
- Baiamonte, Lidia, et al.
(författare)
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Carbide-laden coatings deposited using a hand-held high-velocity air-fuel (HVAF) spray gun
- 2021
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 406
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Tidskriftsartikel (refereegranskat)abstract
- Driven by sustainability and cost considerations, there is growing interest in power generation utilizing renewable sources, especially biomass and waste. While premature degradation of power plant components due to corrosion is well-known, erosion can be a dominant damage mechanism in plants that use “pure” biomass with less corrosive elements like Cl, K, etc. Circulating fluidized bed (CFB) parts are prone to erosion-driven damage and demand periodic re-protection or replacement. In response to the above, this preliminary study evaluates a selection of complex carbide-based coatings to enhance protection against erosion to prolong service life of boiler components. Recognizing on-site coating requirements of real boiler applications, a specific focus is on evaluating performance of a hand-held high-velocity air-fuel (HVAF) spray gun and compare it with the current state-of-the-art high-velocity oxy-fuel (HVOF) deposition. Coatings developed by the above routes have been characterized with microstructural analyses, and their performance evaluated and ranked in an air-jet erosion rig at various impact angles.
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| 4. |
- Battabyal, Manjusha, 1979, et al.
(författare)
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Comparison of microstructure in Ni-Al single splats and millimeter sized drops
- 2011
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Ingår i: Surface Modification Technologies XXV. - 9788191057140 ; , s. 3-12
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Konferensbidrag (refereegranskat)abstract
- Splat studies are a central area of research because they can provide fundamental knowledge on the phenomena controlling the final coating properties such as coating microstructure and adhesion. Wetting and heat transfer are expected to influence the final splat shape while they are in turn controlled by the presence of oxides and adsorbed species on the substrate surface. It is however difficult to follow the flattening of a sprayed droplet at the micrometer scale. Since the mid nineties, so-called free falling experiments have been developed with which it is possible to simulate the thermal spray process. The millimetre sized drops allow investigating the flattening and solidification occurring in milliseconds instead of in microseconds.In this study, the microstructure of plasma sprayed Ni-Al splats and millimetre sized droplets produced on TiAlV and pure Ti substrates, respectively, are compared. By use of scanning electron microscopy (SEM), especially the cross-section of splats and droplets has been investigated. In the splats, diffusion across the splat-substrate interface and the formation of an interface layer is detected. In the droplets, up to 3 different layers are formed at the interface to the substrate. The microstructure at the interface and the phases present are discussed and their influence on heat transfer and coating properties are described.In this study, the microstructure of plasma sprayed Ni-Al splats and millimetre sized droplets produced on TiAlV and pure Ti substrates, respectively, are compared. By use of scanning electron microscopy (SEM), especially the cross-section of splats and droplets has been investigated. In the splats, diffusion across the splat-substrate interface and the formation of an interface layer is detected. In the droplets, up to 3 different layers are formed at the interface to the substrate. The microstructure at the interface and the phases present are discussed and their influence on heat transfer and coating properties are described.
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| 5. |
- Björkeborn, Karin, 1978, et al.
(författare)
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Effects on machining due to microstructure variations in a case hardening steel
- 2008
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Ingår i: Proceedings of the Swedish Production Symposium - 2008.
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Konferensbidrag (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. However, material batches showing a decreased machinability often have properties within the material specification. Thus, for an increased machinability and a more robust production of case hardening steel parts, the relationship between microstructure and machinability needs to be further investigated. In this study, machinability has been evaluated for a specific case hardening steel with respect to pearlite nodular size, phase distribution and interlamellar spacing of pearlite. These variations in microstructure have been achieved by altering the annealing cycle, i.e. austenitizing temperature, holding time and temperature for pearlite formation. The criterions for machinability which are taken into consideration in this investigation are tool wear and chip formation. Furthermore, a comparison of cutting forces and surface integrity for the tested microstructures will be presented. The results from tests show a difference between material with larger pearlite nodules and a material with smaller pearlite nodules. For tool wear, the material with larger pearlite nodules has a decreased machinability. However, for chip formation the result is opposite, and a material with larger pearlite nodules has an increased machinability.
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| 6. |
- Björkeborn, Karin, 1978, et al.
(författare)
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Ranking of materials by their machinability applying a short term test
- 2008
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Ingår i: Proceedings of 2nd International Conference on Innovative Cutting Processes and Smart Machining (INTERCUT 2008), Cluny, France.
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Konferensbidrag (refereegranskat)abstract
- For case hardening steel, the relationship between microstructure and machinability is investigated. To be able to determine the influence of morphology, i.e. grain size, phase distribution and interlamellar spacing in pearlite, homogeneous material is required. However, a homogeneous microstructure can only be guaranteed when small material volumes are used. For that reason the Volvo Standard Machinability Test has been applied, as it allows ranking of materials with respect to their machinability by removing only small amounts of material (~800 mm of a bar with 50 mm diameter for each material). In addition to what is described in the standard of the test, a number of observations and experiences have been made. In this article the observations in connection with the Volvo Standard Machinability Test are critically discussed. Furthermore, the results of the machinability test of the case hardening steels are presented.
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| 7. |
- Björkeborn, Karin, 1978, et al.
(författare)
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Study of machinability of case hardening steel in production environment
- 2009
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Ingår i: Proceedings of the Swedish Production Symposium - 2009.
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Konferensbidrag (refereegranskat)abstract
- The investigation is based on field studies in full scale production and machinability is evaluated in terms of tool wear of cemented carbide inserts. The aim of this study was to investigate how rather small variations in chemical composition between different batches of a case hardening steel affect machinability. Continuous wear is observed to be low for all of the investigated inserts. However, some of the tools show discontinuous wear, like spalling of coating. The discontinuous wear is believed to be caused by unevenness of the forged scale of the machined component and not by variations in the material workpiece bulk properties. Since this wear mechanism may cause a premature tool breakage, it is very important to investigate this finding in more detail. To be able to evaluate the effect of chemical composition on machinability further experiments are necessary, in a more controlled environment with a material having a larger variation in composition.
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| 8. |
- Björkeborn, Karin, 1978, et al.
(författare)
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Study of microstructural influences on machinability of case hardening steel
- 2010
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Ingår i: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 49:5-8, s. 441-446
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Tidskriftsartikel (refereegranskat)abstract
- The overall aim of this study is to establish knowledge about how the material specificationof case hardening steel should be modified in order to create a robust and predictable productionprocess with focus on machinability. In this study, emphasis is laid on studying microstructurevariations produced by changing holding time and temperature in the annealing process. Astandardized milling test was used to assess machinability (with respect to tool wear) as this methodhas the advantage of only needing small diametrical samples and low material volumes. From theresults of the test, it can be concluded that machinability is more influenced by pearlite nodular sizethan by pearlite morphology. Furthermore, it can be stated that hardness is not a suitable criterion fordetermining machinability of case hardening steel. In the manufacturing process of transmission parts(such as gear milling/hobbing) high speed steel tools are commonly used. The same type of tool isapplied in the standardized milling test. However, the obtained ranking (of machinability) for thedifferent materials is also applicable if other types of cutting tools are used.
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| 9. |
- Bouwhuis, Brandon, et al.
(författare)
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Microstructure in work-hardened micro-truss materials given post-forming annealing treatments
- 2010
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Ingår i: Proceedings of 2010 TMS Annual Meeting. ; CD
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Konferensbidrag (refereegranskat)abstract
- Micro-truss cellular materials can be used as structurally efficient cores in light-weight sandwich panels. These sandwich cores have been produced using deformation-forming approaches, which introduce plastic strain into the truss struts. While this imparted strain can be used to strengthen the overall micro-truss core, it also drives recrystallization and grain growth if sandwich panel assembly involves conventional brazing treatments that subject the truss core to elevated temperatures. In addition to losing a potential strengthening mechanism, brazing can also result in the grain size of the annealed microstructure approaching the cross-sectional dimensions of the micro-truss struts. The present study is an examination of the strut microstructures in aluminum alloy and stainless steel micro-truss materials fabricated using a deformation-forming approach, and following a post-fabrication annealing step. These results serve as a guideline for future sandwich panel thermal processing to minimize the reduction of strength due to annealing and detrimental size effects.
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| 10. |
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| 11. |
- Choi, Pyuck-Pa, et al.
(författare)
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Thermal stability of electrodeposited nanocrystalline Co-1.1at%P
- 2005
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Ingår i: Acta Materialia. ; 53:16, s. 4473-4481
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Tidskriftsartikel (refereegranskat)abstract
- Nanocrystalline Co-1.1at.%P prepared by pulsed electrodeposition was investigated with respect to thermal stability. Several characterization methods such as differential scanning calorimetry, X-ray diffraction, transmission electron microscopy, field ion microscopy and tomographic atom probe were applied. Between 673 and 733 K, the allotropic phase transformation (hcp-Co to fcc-Co) sets in and abnormal grain growth is observed. It is suggested that there is a synergistic effect between abnormal grain growth and the allotropic phase transformation. Between 733 and 753 K, the P excess of the grain boundaries decreases, Co2P and CoP precipitates form, and normal grain growth occurs. Thus, the P-segregation to the grain boundaries is held responsible for the increased thermal stability of Co-1.1at.%P at temperatures below 753 K. The thermal stability of this alloy can be mainly attributed to the reduction of grain-boundary energy.
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| 12. |
- Cialone, Matteo, et al.
(författare)
-
Tailoring magnetic properties of multicomponent layered structure via current annealing in FePd thin films
- 2017
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Multicomponent layered systems with tailored magnetic properties were fabricated via current annealing from homogeneous Fe67Pd33 thin films, deposited via radio frequency sputtering on Si/SiO2 substrates from composite target. To promote spontaneous nano-structuring and phase separation, selected samples were subjected to current annealing in vacuum, with a controlled oxygen pressure, using various current densities for a fixed time and, as a consequence, different phases and microstructures were obtained. In particular, the formation of magnetite in different amount was observed beside other iron oxides and metallic phases. Microstructures and magnetic properties evolution as a function of annealing current were studied and interpreted with different techniques. Moreover, the temperature profile across the film thickness was modelled and its role in the selective oxidation of iron was analysed. Results show that is possible to topologically control the phases formation across the film thickness and simultaneously tailor the magnetic properties of the system.
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| 13. |
- da Silva, Melina, 1978, et al.
(författare)
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A comparison of thermal stability in nanocrystalline Ni- and Co-based materials
- 2005
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Ingår i: International Journal of Materials Research. - : Walter de Gruyter GmbH. - 1862-5282 .- 2195-8556. ; 96:09, s. 1009-1014
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Tidskriftsartikel (refereegranskat)abstract
- In this paper the microstructural development upon annealing of nanocrystalline Ni- and Co-based electrodeposits is described. New investigations on Ni, Ni - Fe, and Co-P are compared with previous results on Ni, Co, and Ni -P in terms of microstructural changes and stabilizing mechanisms. The conclusions are: pure nanocrystalline Ni and Co are stabilized by impurities in the grain boundaries. In the case of Co, also an allotropic phase transformation influences the occurrence of abnormal grain growth. Alloying and/or adding solutes is found to increase thermal stability. While in Ni-20 at.% Fe the ordering transformation is expected to be the reason for stabilization, in strongly segregating systems (Ni -P and Co-P) the stabilizing effect is the decrease in grain boundary energy due to solute segregation. After precipitation, Zener pinning still hinders grain boundary migration, but not sufficient to stabilize the nanocrystalline structure.
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| 14. |
- da Silva, Melina, 1978, et al.
(författare)
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Analytical TEM study of annealed nanocrystalline cobalt–phosphorous electrodeposits
- 2007
-
Ingår i: Journal of Microscopy. ; 228, s. 338-344
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Tidskriftsartikel (refereegranskat)abstract
- Investigation of thermal stability of two nanocrystallineCo–P alloys shows that P atoms segregate to the grainboundaries upon annealing until precipitation of Co2Pand CoP precipitates takes place. The P-rich precipitatesformed have been investigated by analytical transmissionelectron microscopy to obtain statistical results of precipitate size, volume fraction and spatial distribution. Electron spectroscopic imaging maps show that the P-rich precipitates are 33 ± 9 nm in Co–1.1at.%P and 33 ± 12 nm in Co–3.2at.%P. The main differences between the alloys are the precipitate size distribution (Co–3.2at.%P having broader distribution) and precipitate volume number density (Co–3.2at.%P has 1.8 times more precipitates than Co–1.1at.%P). The volume fraction of precipitates is 3.0% in Co–1.1at.%P and 4.4% in Co–1.1at.%P. Most of the precipitates are of nearly spherical or slightly elongated shape, and only a few have a plateletlike shape as expected from previous tomographic atom probe measurements. Due to the truncation and projection effects, the composition of the precipitates could not be determined.
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| 15. |
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| 16. |
- da Silva, Melina, 1978, et al.
(författare)
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Enhanced thermal stability of a cobalt-boron carbide nanocomposite by ion-implantation
- 2007
-
Ingår i: International Journal of Materials Research. ; 98:11, s. 1124-1130
-
Tidskriftsartikel (refereegranskat)abstract
- A first investigation of the thermal stability in a wear resistant cobalt-boron carbide (Co–B4C) nanocomposite hasbeen performed by the combination of calorimetry andtransmission electron microscopy. The calorimetric measurements show that the thermal stability of Co–B4C is not influenced by the presence of the 10 vol.% lm-sized boron carbide particles. However, grain growth is shifted to significantly higher temperatures during in-situ annealing (in the transmission electron microscope), and abnormal grain growth is not observed to be as extensive as in conventional nanocrystalline Co. This effect is mainly attributed to the observed implantation of Ga atoms during transmission electron microscope specimen thinning by focused ion beam. Grain boundary segregation mechanisms are discussed as possible reasons for the retarded grain growth.
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| 17. |
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| 18. |
- Deckers, Tobias, et al.
(författare)
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Impact of processing gas composition on process stability and properties of PBF-LB/M processed alloy 718
- 2024
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Ingår i: Journal of Manufacturing Processes. - 1526-6125. ; 120, s. 712-718
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Tidskriftsartikel (refereegranskat)abstract
- The almost unlimited design freedom of the laser-based powder bed fusion of metals (PBF-LB/M) makes this technology very attractive for industry. However, as a developing technology, it still faces some challenges when it comes to productivity and robustness, to name some. Whereas numerous studies covered the impact of laser-based parameters on material properties and robustness, the effect of the processing gas received limited attention. The objective of this study was to evaluate the effect of processing gas composition, containing helium (He) and hydrogen (H2), compared to conventionally used argon (Ar), during PBF-LB/M processing of virgin alloy 718 powder, on printing behavior and part properties. The four gases studied were Ar, Ar +30%He, Ar +30%He +2%H2, and Ar +70%He. Optical Tomography (OT) was used to monitor process stability, which unveiled a significant decrease in process-by products (spatters) between 51 % and 89 % using He and H2-containing gases. It was also found that the process gas decreased the bulk porosity from an average value of 0.08 % when processed with Ar to 0.04 % when using Ar + 70%He. The oxygen pickup by the spatter particles was reduced from 630 ppm (Ar) to 331 ppm (Ar +70%He). EBSD analysis revealed that there were no evident changes in microstructure with the processing gas. The samples processed also had similar tensile properties with yield and ultimate tensile strength of 1180 MPa and 1395 MPa, respectively. However, there was a slight increase in ductility from 16.5 % to 17.2 %, when processed with pure Ar and Ar + 70%He, respectively. This study shows that utilizing standard Ar processing atmosphere with He addition leads to a more stable process with reduced spatter, porosity and a marginal increase in ductility for Alloy 718.
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| 19. |
- Ekberg, Johanna, 1987, et al.
(författare)
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Analysis of single splats produced by axial suspension plasma spraying
- 2018
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Ingår i: Surface Engineering. - : Informa UK Limited. - 1743-2944 .- 0267-0844. ; 34:5, s. 407-411
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Tidskriftsartikel (refereegranskat)abstract
- Axial suspension plasma spraying (ASPS) is a relatively new, innovative technique with which microstructures have been produced that are similar to the ones produced by electron beam physical vapor deposition. They have a columnar structure and consist of nm- and µm-sized pores. However, so far the formation of the microstructure is not fully understood because fragmentation and vaporisation of the liquid significantly affects the deposition process. Analysis of single splats can provide important information on the phenomena controlling the coating formation process and the final coating properties. Therefore, the present study aims at providing first results of 8 wt-% yttria-stabilised zirconia single splats sprayed onto a steel substrate by use of ASPS. Scanning electron microscopy and atomic force microscopy have been used to characterise the splats with respect to appearance, shape, and size distribution.
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| 20. |
- Ekberg, Johanna, 1987, et al.
(författare)
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Porosity investigation of yttria-stabilized zirconia topcoats using NMR cryoporometry
- 2017
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Ingår i: Surface and Coatings Technology. - : Elsevier BV. - 0257-8972. ; 315, s. 468-474
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Tidskriftsartikel (refereegranskat)abstract
- Axial suspension plasma spraying (ASPS) is a new, innovative plasma spray technique using a feedstockconsisting of fine powder particles suspended in a liquid. With ASPS, thermal barrier coating (TBC) topcoatswith columnar structures have been produced that are built up by fine powder particles. The microstructure consistsof micro-,meso-, and macro-pores. Due to thewide pore size range including nano-porosity it is challengingto measure porosity and pore size distribution in TBC topcoats. However, it is important to characterize the porousstructure as it affects the thermal conductivity. Nuclear magnetic resonance (NMR) cryoporometry is apromising method for performing such measurements because of its capability of measuring pores down tonanometer size and providing information about the pore geometry. The aim of this paper is to introduce NMRcryoporometry as a newcharacterization technique for determining porosity, pore size distribution and pore geometryof TBC topcoats produced by ASPS. The study includes the comparison of two different yttria-stabilizedzirconia topcoats and NMR cryoporometry is complemented by microstructural characterization using scanningelectron microscopy.
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| 21. |
- Ekberg, Johanna, 1987, et al.
(författare)
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Porosity measurements on heat treated suspension plasma sprayed YSZ coatings using NMR cryoporometry
- 2017
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Ingår i: International Thermal Spray Conference 2017 Proceedings. - 9783961440009 ; DVS-Berichte Volume 336, s. 308-313
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Konferensbidrag (refereegranskat)abstract
- Suspension plasma sprayed (SPS) coatings can be produced with fine powder particles and tailor-made porosity.This allows to achieve low thermal conductivity which makes the coatings attractive as e.g. topcoats in thermalbarrier coatings (TBCs). Used in gas turbine applications, the TBCs are exposed to high temperatures which leadsto alterations of the microstructure. To obtain coatings with optimized properties, possible microstructurealterations like closing of pores and opening of cracks have to be taken into account. Hence, in this study, TBCtopcoats consisting of 8 wt.% yttria-stabilized zirconia (YSZ) were heat treated in air at 1150°C and thereafterinvestigated using scanning electron microscopy, X-ray diffraction, and nuclear magnetic resonance (NMR)cryoporometry. For all investigated samples, the porosity decreased as a result of the heat treatment. The finerpores and cracks disappeared and the larger pores grew slightly and achieved a more distinct shape as thematerial seemed to become more compact.
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| 22. |
- Ekberg, Johanna, 1987, et al.
(författare)
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The Influence of Heat Treatments on the Porosity of Suspension Plasma-Sprayed Yttria-Stabilized Zirconia Coatings
- 2018
-
Ingår i: Journal of Thermal Spray Technology. - : Springer Science and Business Media LLC. - 1059-9630 .- 1544-1016. ; 27:3, s. 391-401
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Tidskriftsartikel (refereegranskat)abstract
- Suspension plasma-sprayed coatings are produced using fine-grained feedstock. This allows to control the porosity and to achieve low thermal conductivity which makes the coatings attractive as topcoats in thermal barrier coatings (TBCs). Used in gas turbine applications, TBCs are exposed to high temperature exhaust gases which lead to microstructure alterations. In order to obtain coatings with optimized thermomechanical properties, microstructure alterations like closing of pores and opening of cracks have to be taken into account. Hence, in this study, TBC topcoats consisting of 4 mol.% yttria-stabilized zirconia were heat-treated in air at 1150 °C and thereafter the coating porosity was investigated using image analysis (IA) and nuclear magnetic resonance (NMR) cryoporometry. Both IA and NMR cryoporometry showed that the porosity changed as a result of the heat treatment for all investigated coatings. In fact, both techniques showed that the fine porosity decreased as a result of the heat treatment, while IA also showed an increase in the coarse porosity. When studying the coatings using scanning electron microscopy, it was noticed that finer pores and cracks disappeared and larger pores grew slightly and achieved a more distinct shape as the material seemed to become more compact.
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| 23. |
- Farooq, Muhammad, 1973, et al.
(författare)
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EBSD and EDX analysis at the cladding-substrate interface of a laser clad railway wheel
- 2006
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Ingår i: International Journal of Materials Research. - : Walter de Gruyter GmbH. - 1862-5282 .- 2195-8556. ; 97:11, s. 1512-1518
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Tidskriftsartikel (refereegranskat)abstract
- Electron backscatter diffraction and energy-dispersive X-ray spectrometry were used to investigate the intermixed interface produced during laser cladding of a Co - Cr -Mo alloy on a steel substrate. A multi-component system and rapid solidification conditions together lead to a complex microstructure at the interface. The solidification of the cladding starts with the formation of an interface layer, which is about 75 mu m in thickness and consists of randomly oriented equiaxed grains of Co-Cr -Fe solid solution and martensite. Orientation analysis of the grains in the interface layer revealed that some grains have a special orientation relationship with the former austenite grains in the heat affected zone but the cladding is not formed by epitaxial growth on the substrate. Intermixing of the materials at the interface is providing a strong bond between the substrate and the cladding. For a grain from the interface layer to emerge as columnar grain in the cladding, it was determined that its crystallographic direction is not supposed to deviate more than 25 degrees from the sample normal direction.
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| 24. |
- Farooq, Muhammad, 1973, et al.
(författare)
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Microstructural characterisation of a Co-Cr-Mo laser clad applied on railway wheels
- 2006
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Ingår i: International Journal of Materials Research. - 1862-5282. ; 97:6, s. 838-844
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Tidskriftsartikel (refereegranskat)abstract
- A Co - Cr -Mo laser cladding applied on railway wheels is characterised by a combination of EBSD and EDX. A complete pass of the cladding is investigated to achieve a better understanding of the microstructure evolution during laser cladding. A microstructure with columnar grains extending over the whole thickness of the cladding is observed. The grains have a -fibre texture with the fibre axis parallel to the normal of the substrate surface, and a substructure consisting of cells/dendrites. During the cladding process, two different kinds of precipitates form in the cell walls, which can be identified as M6C and a non-equilibrium phase. Furthermore, stacking faults are observed to occur in the cladding grains and are discussed with respect to the laser cladding process.
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| 25. |
- Farooq, Muhammad Umar, 1973, et al.
(författare)
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EBSD characterization of carbide-carbide boundaries in WC-Co
- 2004
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Ingår i: Journal of Microscopy. ; 213:March, s. 306-312
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Tidskriftsartikel (refereegranskat)abstract
- A sample of WC-6wt%Co was investigated for grain boundary character distribution and occurence of coincidence site lattice (CSL) boundaries on a statistical basis. For this purpose orientation measurements of the grains were carried out using electron back-scattered diffraction (EBSD). The dominant misorientation relationships were determined by complementary EBSD data representation tools such as orientatin maps, misorientation angle distribution histograms and the sectioned three-dimensional misorientation space. It was found that the grain boundary character distribution of the material is nearly random and the CSL boundaries are not present in statistically significant amounts. It was also found that the amount of binder phase does not play a role in the formation of special boundaries. The paper focuses on the methodology of characterizing grain boundaries in a hexagonal material using EBSD.
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