Evolution of microstructural complex transitions in low-modulus β-type Ti-35Nb-2Ta-3Zr alloy manufactured by laser powder bed fusion

Noman Hafeez, Daixiu Wei, Lechun Xie, Yujin Tang, Jia Liu, Hidemi Kato, Weijie Lu, Lai Chang Zhang, Liqiang Wang

Research output: Contribution to journalArticlepeer-review

Abstract

Low modulus β-type Ti-35Nb-2Ta-3Zr alloy scaffold was fabricated by laser powder bed fusion (L-PBF). The complex microstructure and mechanical properties were characterized systematically. The martensitic interstitial complex transitions (ICTs) from β to α" (β→α"), α" to ω (α"─ω), and β to α" and ω (β→α''─ω) phases are accompanied by dislocation pile-ups and twins in a heterogeneous manner. A homaloidal transition was observed with astraddle ω and α"M nanolayers and partial nanolayers along the boundaries of the α"T martensitic twin. Crystallographic characterization confirmed that {332}〈113〉 and {112}〈111〉 twinning and shear stress assisted the α─ω and β→α" transitions at the interface of the β region. Both the αꞌꞌ martensitic twin and ω formation were observed adjacent to the {332}〈113〉 type twinning mode. The [332] twinning were instigated and nucleated through ω-phase formation. The secondary [112] twins amid the primary [332] twinning were instigated and nucleated through ω-phase formation. Multiple slip bands were identified on the surface of the micropillar after the microcompression testing. Moreover, high-density dislocations and dislocation pile-ups were found alongside the twins and grain boundaries. In addition, {112}〈111〉 twinning was identified amongst dislocation pile-ups. This work reveals a novel complex phase transformation that could play a significant role in applications such as biomedical implants.

Original languageEnglish
Article number102376
JournalAdditive Manufacturing
Volume48
DOIs
Publication statusPublished - 2021 Dec

Keywords

  • Homaloidal complex microstructure
  • {332}〈113〉 twinning
  • α" martensitic transformation
  • α─ω transition
  • ω nanolayers

ASJC Scopus subject areas

  • Biomedical Engineering
  • Materials Science(all)
  • Engineering (miscellaneous)
  • Industrial and Manufacturing Engineering

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