Ultrafine grain refinement of biomedical Co-29Cr-6Mo alloy during conventional hot-compression deformation

Kenta Yamanaka, Manami Mori, Shingo Kurosu, Hiroaki Matsumoto, Akihiko Chiba

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94 Citations (Scopus)

Abstract

In order to examine the microstructural evolution during hot-compression deformation of the biomedical Co-29Cr-6Mo (weight percent) alloy without the addition of Ni, hot-compression tests have been conducted at deformation temperatures ranging from 1050 °C to 1200 °C at various strain rates of 10-3 to 10 s-1. The grain refinement due to dynamic recrystallization (DRX) was identified under all deformation conditions by means of field-emission scanning electron microscopy/electron backscattered diffraction (FESEM/EBSD) and transmission electron microscopy (TEM) observations. Although the DRX grain size (d) of the deformed specimens considerably decreased with an increasing Zener-Hollomon (Z) parameter at strain rates ranging from 10-3 to 0.1 s-1, a grain size coarser than that predicted from the d-Z relation was obtained at strain rates of 1.0 and 10 s-1. An ultrafine-grained microstructure with a grain size of approximately 0.6 μm was obtained under deformation at 1050 °C at 0.1 s-1, from an initial grain size of 40 μ m. The grain refinement to a submicron scale of biomedical Co-Cr-Mo alloys has been achieved with hot deformation by ∼60 pct due to DRX, in which the bulging mechanism is not operative. The ultrafine grains obtained due to DRX without bulging is closely related to the considerably low stacking-fault energy (SFE) of the Co-Cr-Mo alloy at deformation temperatures.

Original languageEnglish
Pages (from-to)1980-1994
Number of pages15
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Volume40
Issue number8
DOIs
Publication statusPublished - 2009

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys

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