Effect of nitrogen on the microstructure and mechanical properties of a CoCrMo alloy (original) (raw)
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Effect of nickel content on the processing and microstructure evolution of Co–Cr–Mo–Ni alloys
Materials Science and Engineering: A, 2019
Two type cobalt-chromium-molybdenum-nickel (Co-Cr-Mo-Ni) alloys were prepared by the powder metallurgy technology. The effect of the element powder nickel content on the milling process and then the microstructure evolution and mechanical properties of the sintered alloys was examined. The increase of the element powder Ni promotes the work harden of the product powders and then decreases the porous defects of the sintered samples. With the increase of the nickel content, the morphology of the sintered alloys changes from coarsely nonuniform grains to finer equiaxial grains with fault striations and the phase changes from single hcp phase to a dual phase of hcp and fcc structure. Obvious improvements in the tensile strength and uniform plastic elongation are achieved in the high
Improving the properties of Ni-Based Alloys by Co Addition
IRJET, 2022
Grain refinement is caused by the addition of Co, which is why changing the amount of Co may be regarded to have an effect on both the microstructure and the behavior of corrosion. The behavior of the grain during corrosion is directly influenced by grain refining. After combining the powders of nickel, chromium, aluminum, and cobalt in the appropriate proportions, the alloys were then compacted to produce green pellets as the next step in the synthesis process. In the last step, the samples were created by using a technology called vacuum arc melting and casting. Both x-ray diffraction and optical microscopy were used in order to characterize the samples after they had been produced. The Vickers hardness tester was used to provide an assessment of the surface's toughness. It has been discovered that the characteristics of the alloy have been greatly improved.
Effects of plasma nitriding on mechanical and tribological properties of CoCrMo alloy
Surface and Coatings Technology, 2008
Surface treatments of orthopedic materials are commonly used to enhance mechanical and tribological properties. One of the well-known orthopedic materials, wrought CoCrMo alloy was nitrided at various temperatures and time periods at a gas mixture of 75%N 2 -25%Ar to achieve these enhancements. SEM, XRD, pin-on-disc tribotester, and microhardness tester have been used to examine the treated materials. Analyses confirm the formation of nitride layers and the significant effect of plasma nitriding on wear rate and surface hardness.
Nitriding of Co–Cr–Mo alloy in nitrogen
Materials Chemistry and Physics, 2014
This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.
Effect of nickel addition on microstructure and properties of Ti-Co-Ni alloys
Biomaterials, 1995
The focus of this study was placed on the effect of nickel addition (5 wt%) on the microstructure, castability, biocorrosion resistance and some other properties of a series of cast high-cobalt (up to 25 wt%) Ti-Co-Ni alloys. Results indicated that melting temperatures of the present alloys were much lower than the melting temperature of pure titanium. Addition of 5 wt% Ni to replace an equivalent amount of Co slightly lowered the eutectoid and melting temperatures. Castability of the alloys was enhanced by the high alloy content and higher mould temperature. Substitution of 5 wt% Ni for Co increased the castability values. The phase transformation of fi-Ti to cr-Ti was enhanced by nickel addition and higher mould temperature. Microhardness of the alloys increased with cobalt content and decreased with mould temperature. The addition of nickel lowered the hardness of the alloys. Breakdown potentials of the alloys were all higher than 900 mV and the critical anodic current densities were all lower than 8 PA cm-*.
Journal of Alloys and Compounds, 2009
Five cast cobalt alloys based on Co-8Ni-30Cr-0.4/0.45C and containing Ta, Nb, Hf and/or Zr were studied by metallography in the as-cast condition and after treatments at 1300 • C. The obtained MC carbides were all interdendritic with a eutectic script-like morphology. For similar carbon contents, the HfC carbides are the most developed in the as-cast microstructure and the most stable at 1300 • C. As-cast, the TaC carbides are less developed than the former and they tend to become more fractioned and less present in microstructure at 1300 • C. The NbC carbides, which have initially the same morphology and the same fraction as TaC, rapidly dissolve at 1300 • C. The cobalt alloys containing HfC or TaC are chromia -forming at 1300 • C. The NbC-containing alloy catastrophically oxides after only few hours at 1300 • C. The average hardness is the highest for the HfC-containing alloy and the lowest for the NbC-containing alloy.
COMPARISON OF MECHANICAL PROPERTIES AND FRACTURE BEHAVIOUR OF Co-BASE AND Ni-BASE ALLOYS
2012
The specific desired properties for structures and components capable of operating under critical loading conditions require the development and use of special materials. Especially in the field of jet aircraft and marine engines, power generation plants and chemical industry is the urgent need of high-strength materials which have to resist high temperatures, special corrosion environments and considerable mechanical loadings. One of the perspective approaches to satisfying these specific requirements is an application of heat resistant Ni-base and/or Co-base alloys. Presented paper is concerned with an experimental study of mechanical properties and fracture behaviour of the Ni-alloy 141I and Co-alloy Stellit. The both alloys were received in the state after casting with no following heat treatment. Wide experimental programme of tensile and Charpy tests in temperature range from 20°C to 1000°C, and constant-load tensile creep tests was done. Fractographic analyses were performed ...
2014
We report the effects of carbon concentration on the microstructures and tensile deformation behaviors of thermomechanically processed Ni-free Co-29Cr-9W-1Si-C (mass%) alloys designed for use as disk materials in CAD/CAM dental technology. The alloy specimens, which contained carbon in different concentrations, were prepared by casting and subsequent hot rolling. Overall, the developed Ni-free alloys with added carbon showed an excellent combination of high strength and high ductility. The precipitates were identified in all of the alloy specimens. 2 Intermetallic compounds, i.e., the Laves and ı phases, were formed in the low-carbon alloys, whereas the precipitates changed to M 23 C 6 carbide when the carbon concentration exceeded 0.1 mass%. Carbon concentrations less than 0.1 mass% exhibited minimal contribution to strengthening, but the formation of the M 23 C 6 carbide particles increased the alloy strength. On the other hand, elongation-to-failure increased with increasing carbon content when the carbon concentration is relatively low. However, the coarse M 23 C 6 carbide particles formed by higher concentrations of carbon were detrimental to ductility. Thus, a maximum elongation-to-failure was obtained at carbon concentrations of around 0.1 mass%. The results of the current study can aid in the design of biomedical Co-28Cr-9Wí1Si-based alloys containing carbon.