Single crystal growth and its microstructure in Co-Cr-Mo alloys for biomedical applications

Takayoshi Nakano, Keita Sasaki, Koji Hagihara, Takuya Ishimoto, Yusuke Fujii, Ai Serizawa

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

2 Citations (Scopus)

Abstract

Co-Cr-Mo based alloys have been widely employed as heat resistant materials and as biomaterials for implants because of their high strength and superior wear resistance. In general, the alloys exhibit a very complicated composition-dependent microstructure containing stacking faults and related mechanical properties. Thus, the essential properties must be clarified by using not only polycrystals but also single crystals. To our knowledge, single crystals and related properties have not been reported elsewhere. Thus, Co-Cr-Mo single crystals were grown and used to analyze the microstructure and the related properties. Single crystals with a composition Co-27 mass% Cr-6 mass% Mo alloy defined by ASTM F75 were grown by two single crystal apparatuses: the optical floating zone and the Bridgman methods. The single crystals with the smooth-surface shape were successfully obtained in the Bridgman method under an Ar gas atmosphere at a crystal growth rate of 5.0 or 2.5 mm/h. A portion of the crystals contain Al as Al 2O 3 precipitates from the crucible. Since the Al 2O 3 precipitate induces martensitic phase transformation from fcc (?) phase to hcp (ε) phase, the single crystals were separated into two parts (a) containing Al 2O 3 precipitate and (b) in the absence of the clear precipitate. The microstructure was significantly altered by the martensitic phase transformation from the ? to ε phase induced by stress field or heating. In addition, variant formation of ε phase has a large influence on the mechanical functions of these Co-Cr-Mo alloys. Novel findings were preliminary obtained in the single crystals.

Original languageEnglish
Title of host publicationTHERMEC 2011
Pages561-565
Number of pages5
DOIs
Publication statusPublished - 2012 Jan 30
Event7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011 - Quebec City, QC, Canada
Duration: 2011 Aug 12011 Aug 5

Publication series

NameMaterials Science Forum
Volume706-709
ISSN (Print)0255-5476

Conference

Conference7th International Conference on Processing and Manufacturing of Advanced Materials, THERMEC'2011
CountryCanada
CityQuebec City, QC
Period11/8/111/8/5

Keywords

  • Artificial joint
  • Biomaterials
  • Co-Cr-Mo alloy
  • Implant
  • Phase transformation
  • Single crystal
  • Stacking fault

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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  • Cite this

    Nakano, T., Sasaki, K., Hagihara, K., Ishimoto, T., Fujii, Y., & Serizawa, A. (2012). Single crystal growth and its microstructure in Co-Cr-Mo alloys for biomedical applications. In THERMEC 2011 (pp. 561-565). (Materials Science Forum; Vol. 706-709). https://doi.org/10.4028/www.scientific.net/MSF.706-709.561