Phase transformation and microstructures in Ti–Al–Nb–Ta system

A variety of heat treatment has been carried out to explore the transformation and microstructure in a Ti–22Al–20Nb–7Ta. Special emphasis focused on the effect of solution and/or aging in O+B2 (orthorhombic+bcc) phase field. Two forms of the transformation of B2 to O phase were observed. They are gr...

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Bibliographic Details
Published in:Materials letters 2002-03, Vol.53 (1), p.57-62
Main Authors: Peng, Jihua, Li, Shiqiong, Mao, Yong, Sun, Xunfang
Format: Article
Language:English
Subjects:
Applied sciences
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Intermetallics
Materials science
Metals. Metallurgy
Microstructure
Phase transformation
Physics
Solid solution hardening, precipitation hardening, and dispersion hardening
aging
Solid solution, precipitation, and dispersion hardening
aging
Ti 2AlNb-based alloy
Ti–Al–Nb–Ta system
Treatment of materials and its effects on microstructure and properties
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Summary:A variety of heat treatment has been carried out to explore the transformation and microstructure in a Ti–22Al–20Nb–7Ta. Special emphasis focused on the effect of solution and/or aging in O+B2 (orthorhombic+bcc) phase field. Two forms of the transformation of B2 to O phase were observed. They are grain size change that is controlled by grain boundary diffusion and Widmanstätten precipitation of O phase from the B2 matrix. It has been found that Ta addition in Ti 2AlNb-based alloy could increase the Widmanstätten transformation starting temperature W s, which determines the transformation mode of B2 to O phase. During recrystallization of O grain, it evolves into lath microstructure. The primary α 2 phase is relatively stable when Ti–22Al–20Nb–7Ta was heat treated in O+B2 phase field, while the transformation of α 2 to O phase occurred in this study.
ISSN:0167-577X
1873-4979
DOI:10.1016/S0167-577X(01)00453-0