Role of strain-induced martensitic transformation on extrusion and intrusion formation during fatigue deformation of biomedical Co-Cr-Mo-N alloys

Takuya Mitsunobu, Yuichiro Koizumi, Byoung Soo Lee, Kenta Yamanaka, Hiroaki Matsumoto, Yunping Li, Akihiko Chiba

Research output: Contribution to journalArticle

25 Citations (Scopus)

Abstract

The mechanism of extrusion and intrusion formation in Co-Cr-Mo-N alloys during fatigue deformation was investigated. In particular, we focused on the role of the strain-induced martensitic transformation (SIMT), which is the transformation of the metastable γ face-centered cubic (fcc) phase into a stable ε hexagonal close-packed (hcp) phase at room temperature because of the gliding of Shockley partial dislocations in the γ-phase matrix. We found that the SIMT also plays a crucial role in the formation of extrusions and intrusions. Further, the morphology of the extrusions and intrusions formed in the Co-Cr-Mo-N alloy specimens was very different from that seen in other fcc alloys. The extrusions and intrusions were formed by the gliding of perfect dislocations with a Burgers vector of perfect <a> dislocation on the basal plane of the ε-hcp phase. This suggests that the ε-phases introduced by the SIMT can deform readily.

Original languageEnglish
Pages (from-to)377-385
Number of pages9
JournalActa Materialia
Volume81
DOIs
Publication statusPublished - 2014 Dec

Keywords

  • Biomedical cobalt-chromium-molybdenum alloy
  • Deformation structure
  • Fatigue crack initiation
  • Martensitic phase transformation
  • Transmission electron microscopy (TEM)

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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