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 language | English |
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Pages (from-to) | 377-385 |
Number of pages | 9 |
Journal | Acta Materialia |
Volume | 81 |
DOIs | |
Publication status | Published - 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