Effect of nitrogen content on microstructure of hot-pressed Co-Cr-Mo alloy compacts for biomedical applications

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5 Citations (Scopus)

Abstract

The gas atomized Co-29Cr-6Mo alloy powder was hot-pressed in Ar, Ar and N2 (Ar + N2), and N2 atmosphere at 1273 K and 80 MPa for 7.2 ks. Nitrogen content in the compacts can be controlled by the mixture ratio of Ar and N2 gases and the compacts contains nitrogen as high as 0.81 mass%. Microstructure and constituent phase of the compacts depends on the nitrogen content. In the compacts containing nitrogen less than 0.2%, the γ(fcc) ε (hcp) and σ phases coexist in the compacts. The volume fraction of σ phase decreases with increasing nitrogen content up to 0.2%. The γ phase is dominantly confirmed in the compacts with nitrogen content of approximately 0.2%. In the compacts containing nitrogen over 0.2%, Cr2N phases in addition to the γ and ε phases are detected in the compacts. This result suggests nitrogen suppress the σ phases formation and stabilize γ phase in the Co-29Cr-6Mo alloy. When the Co-29Cr-6Mo alloy compacts are hot-pressed with Cr2N powder as a nitrogen source, the σ and nitrides coexist and the microstructure is inhomogeneous. Therefore, it is found that controlling the mixture ratio of Ar and N2 gases during hot-pressing is effective methods to distribute nitrogen uniformly in the Co-Cr-Mo alloy compacts.

Original languageEnglish
Pages (from-to)875-880
Number of pages6
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume72
Issue number11
DOIs
Publication statusPublished - 2008 Nov

Keywords

  • Cobalt-chromium-molybdenum alloy compacts
  • Hot-pressing
  • Nitride
  • Nitrogen gas
  • σ phase

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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