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

Author Identifier

L. C. Zhang

ORCID : 0000-0003-0661-2051

Document Type

Journal Article

Publication Title

Additive Manufacturing

Volume

48

Publisher

Elsevier

School

School of Engineering

RAS ID

37023

Funders

Japan Society for the Promotion of Science

Comments

Hafeez, N., Wei, D., Xie, L., Tang, Y., Liu, J., Kato, H., . . . Wang, L. (2021). Evolution of microstructural complex transitions in low-modulus β-type Ti-35Nb-2Ta-3Zr alloy manufactured by laser powder bed fusion. Additive Manufacturing, 48(Part A), article 102376. https://doi.org/10.1016/j.addma.2021.102376

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.

DOI

10.1016/j.addma.2021.102376

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