Heterogeneous α phase precipitation and peculiar aging strengthening in biomedical β-type Ti-Nb-Ta-Zr alloy having vortical structure

Kengo Narita, Mitsuo Niinomi, Masaaki Nakai, Kazuya Oribe

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Microstnictural evolution accompanying mechanical properties change by aging treatment at 723 K in cold-swaged Ti29Nb-13Ta-4.6Zr were investigated in order to obtain an optimized aging condition for getting excellent mechanical properties. The precipitate free zone exists in Ti-29Nb-13Ta-4.6Zr after aging treatment for various time periods. Such the precipitate free zone corresponds to Nb and Ta-enriched region according to the result of element-distribution analysis. With the increase in aging time, the area of the precipitate free zone decreases. Two types of α phase, acicular and ellipsoidal ones, are observed in Ti-29Nb-13Ta-4.6Zr after aging treatment for various time periods. The acicular α phase is precipitated in the Ti- and Zr-enriched region. While the size increases, the area fraction barely changes with aging time for acicular α phase, On the other hand, the ellipsoidal α phase precipitates at ß grain boundary and its subgrain boundary. Both the size and area fraction increase with the increase in aging time for the ellipsoidal a phase. The lattice correspondence between acicular α phase and ß matrix is [1̄10]β//[121̄]α, (112) β//(2̄10)α and [̄10] β//[001]α, (112)β//(200)α until 86.4 ks of aging time. However, the lattice correspondence of [1̄10]β//[121̄]α, (112)β// (̄210)α disappear over 259.2 ks of aging time. Tensile strength of Ti-29Nb-13Ta-4.6Zr subjected to aging treatment after cold swaging is around 1200 GPa, regardless of aging time. On the other hand, elongation of those are decreased by the aging treatment up to 86.4 ks, increased at ones over 259.2 ks.

Original languageEnglish
Pages (from-to)198-206
Number of pages9
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume75
Issue number4
DOIs
Publication statusPublished - 2011 Apr

Keywords

  • Aging treatment
  • Beta type
  • Biomaterial
  • Intergranular alpha phase
  • Intragranular alpha phase
  • Medical device
  • Micro segregation
  • Orthopedics
  • Thermo mechanical treatment
  • Titanium alloy

ASJC Scopus subject areas

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

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