ω Transformation in cold-worked Ti-Nb-Ta-Zr-O alloys with low body-centered cubic phase stability and its correlation with their elastic properties

M. Tane, T. Nakano, S. Kuramoto, M. Niinomi, N. Takesue, H. Nakajima

Research output: Contribution to journalArticle

59 Citations (Scopus)

Abstract

The ω transformation and its correlation with elastic properties were investigated in cold-worked Ti-36Nb-2Ta-3Zr-xO mass% alloys with low body-centered cubic (β) phase stability, known as gum metal. Analysis of the temperature dependence of the ω (hexagonal) phase formation using transmission electron microscopy and of the elastic properties of solution-treated and cold-worked alloys using resonant ultrasound spectroscopy revealed that in the solution-treated 0.36% and 0.51% O alloys, the high concentration of oxygen suppressed ω-phase formation from room temperature to a fairly low temperature of ∼13 K. However, the ω phase was formed by cold working at room temperature in the 0.30% and 0.47% O alloys. Importantly, the fraction of the ω phase clearly increased upon cooling, which indicates that the formation of the ω phase is thermodynamically favorable near and below room temperature in the cold-worked 0.30% and 0.47% O alloys. This formation of the ω phase and the low stability of the β phase related to the low electron/atom (e/a) ratio were the dominant factors determining the elastic properties near and below room temperature in the cold-worked Ti-Nb-Ta-Zr-O alloys.

Original languageEnglish
Pages (from-to)139-150
Number of pages12
JournalActa Materialia
Volume61
Issue number1
DOIs
Publication statusPublished - 2013 Jan 1

Keywords

  • Acoustic methods
  • Elastic properties
  • Omega phase
  • Oxygen
  • Titanium alloys

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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