Microstructural evolution and mechanical properties of biomedical Co-Cr-Mo alloy subjected to high-pressure torsion

Murat Isik, Mitsuo Niinomi, Ken Cho, Masaaki Nakai, Huihong Liu, Hakan Yilmazer, Zenji Horita, Shigeo Sato, Takayuki Narushima

Research output: Contribution to journalArticle

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Abstract

The effects of severe plastic deformation through high-pressure torsion (HPT) on the microstructure and tensile properties of a biomedical Co-Cr-Mo (CCM) alloy were investigated. The microstructure was examined as a function of torsional rotation number, N and equivalent strain, εeq in the HPT processing. Electron backscatter diffraction analysis (EBSD) shows that a strain-induced martensitic transformation occurs by the HPT processing. Grain diameter decreases with increasing εeq, and the HPT-processed alloy (CCMHPT) for εeq=45 exhibits an average grain diameter of 47nm, compared to 70μm for the CCM alloy before HPT processing. Blurred and wavy grain boundaries with low-angle of misorientation in the CCMHPT sample for εeq<45 become better-defined grain boundaries with high-angle of misorientation after HPT processing for εeq=45. Kernel average misorientation (KAM) maps from EBSD indicate that KAM inside grains increases with εeq for εeq<45, and then decreases for εeq=45. The volume fraction of the ε (hcp) phase in the CCMHPT samples slightly increases at εeq=9, and decreases at εeq=45. In addition, the strength of the CCMHPT samples increases at εeq=9, and then decrease at εeq=45. The decrease in the strength is attributed to the decrease in the volume fraction of ε phase, annihilation of dislocations, and decrease in strain in the CCMHPT sample processed at εeq=45 by HPT.

Original languageEnglish
Pages (from-to)226-235
Number of pages10
JournalJournal of the Mechanical Behavior of Biomedical Materials
Volume59
DOIs
Publication statusPublished - Jun 1 2016

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Microstructural evolution
Torsional stress
Mechanical properties
Processing
Electron diffraction
Volume fraction
Grain boundaries
Microstructure
Martensitic transformations
Tensile properties
Plastic deformation

All Science Journal Classification (ASJC) codes

  • Biomaterials
  • Biomedical Engineering
  • Mechanics of Materials

Cite this

Microstructural evolution and mechanical properties of biomedical Co-Cr-Mo alloy subjected to high-pressure torsion. / Isik, Murat; Niinomi, Mitsuo; Cho, Ken; Nakai, Masaaki; Liu, Huihong; Yilmazer, Hakan; Horita, Zenji; Sato, Shigeo; Narushima, Takayuki.

In: Journal of the Mechanical Behavior of Biomedical Materials, Vol. 59, 01.06.2016, p. 226-235.

Research output: Contribution to journalArticle

Isik, Murat ; Niinomi, Mitsuo ; Cho, Ken ; Nakai, Masaaki ; Liu, Huihong ; Yilmazer, Hakan ; Horita, Zenji ; Sato, Shigeo ; Narushima, Takayuki. / Microstructural evolution and mechanical properties of biomedical Co-Cr-Mo alloy subjected to high-pressure torsion. In: Journal of the Mechanical Behavior of Biomedical Materials. 2016 ; Vol. 59. pp. 226-235.
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