Effect of Nitrogen on Microstructure of Porous CoCrMo Alloy Compacts for Biomedical Applications
Porous Co-29Cr-6Mo alloy compacts were fabricated and their microstructures were examined. The Co-29Cr-6Mo alloy powders were atomized by using Plasma Rotating Electrode Process (PREP) in an Ar atmosphere. These powders were hot-pressed at 1223 K in Ar or nitrogen and annealed at 1473 K in vacuum or nitrogen. X-ray analysis revealed that the γ phase (f.c.c.) mostly exists in the compact hot-pressed in nitrogen although the ε phase (h.c.p.) is dominant in the compact hot-pressed in Ar. In addition, precipitates are observed at the interdendritic region in the compact hot-pressed in nitrogen. These results suggest that the Co-29Cr-6Mo alloy powders react with nitrogen to stabilize the γ phase. Accordingly, the constituent phase in the Co-29Cr-6Mo alloy is strongly affected by the atmosphere during hot-pressing.
Young Won Chang, Nack J. Kim and Chong Soo Lee
N. Nomura et al., "Effect of Nitrogen on Microstructure of Porous CoCrMo Alloy Compacts for Biomedical Applications", Materials Science Forum, Vols. 561-565, pp. 1501-1504, 2007