Microstructural analysis of biomedical Co-Cr-Mo alloy subjected to high-pressure torsion processing

Murat Isik, Mitsuo Niinomi, Ken Cho, Masaaki Nakai, Junko Hieda, Hakan Yilmazer, Zenji Horita, Takayuki Narushima

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The effect of high-pressure torsion (HPT) processing on the microstructure and Vickers hardness of Co-Cr-Mo (CCM) alloys were investigated in this study. The microstructure of initial CCM alloy contains equiaxed grains with a grain diameter of approximately 50 μm and twins. The clear grain boundaries of equiaxed grains and twins disappear after HPT processing at a rotation number, N, of 10. The phase maps of initial CCM alloy and CCM alloy subjected to HPT processing at N = 5 measured by electron backscatter diffraction exhibit that the ratio of γ phase decreases from 93.5% to 34.1% and the ratio of ε phase increases from 6.5% to 65.9% by applying HPT processing. These results indicate that the ε phase is formed by high-strain, which is induced by the HPT processing. The Vickers hardness values on the surfaces of the CCM alloys subjected to HPT processing at N = 1, 5, and 10 increase with increasing the equivalent strain, εeq. These results suggest that an increase of Vickers hardness is correlated to an increase of the ratio of ε phase and the dislocation density, and grain refinement, which are caused by the high-strain induced by HPT processing.

Original languageEnglish
Title of host publicationAdvanced Ceramics and Novel Processing
PublisherTrans Tech Publications Ltd
Pages263-269
Number of pages7
ISBN (Print)9783038351306
DOIs
Publication statusPublished - 2014
Event5th International Symposium on Advanced Ceramics, ISAC 2013 and 3rd International Symposium on Advanced Synthesis and Processing Technology for Materials, ASPT 2013 - Wuhan, China
Duration: 2013 Dec 92013 Dec 12

Publication series

NameKey Engineering Materials
Volume616
ISSN (Print)1013-9826
ISSN (Electronic)1662-9795

Other

Other5th International Symposium on Advanced Ceramics, ISAC 2013 and 3rd International Symposium on Advanced Synthesis and Processing Technology for Materials, ASPT 2013
CountryChina
CityWuhan
Period13/12/913/12/12

Keywords

  • Co-Cr-Mo alloys
  • Grain refinement
  • High-pressure torsion
  • Metallic biomaterial
  • Strain-induced ε martensite phase
  • Vickers hardness

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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