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Enhanced Hot Workability of Ti–46Al–4Nb–0.1B Alloy by Introducing Adjustable β Phase via Elemental Powder Metallurgy
Author(s) -
Wang Qi,
Chen Guo-qing,
Tang Huaping,
Fu Xue-song,
Zhou Wen-long
Publication year - 2021
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.202000762
Subject(s) - materials science , alloy , lamellar structure , phase (matter) , powder metallurgy , microstructure , metallurgy , deformation (meteorology) , diffusion , creep , composite material , thermodynamics , chemistry , organic chemistry , physics
TiAl‐base alloys are a kind of promising materials for high‐temperature applications. The β phase existing in TiAl alloy can improve the hot workability, but deteriorates the creep properties. Preparing a β phase‐containing TiAl‐base alloy to enhance the hot workability before hot deformation and eliminating the β/B2 phase by postheat treatment to improve the service performance is a good strategy. Herein, a significant volume fraction of β phase is obtained in the Ti–46Al–4Nb–0.1B alloy by the elemental powder metallurgy (EPM), and the β/B2 phase is eliminated by the subsequent heat treatment. The results demonstrate that the microstructure of the EPMed Ti–46Al–4Nb–0.1B alloy predominantly consists of α 2 /γ lamellar colonies, equiaxial γ grains, and some randomly distributed β phase and σ‐Nb 2 Al phase. The β/B2 phase formed at the Nb‐enriched regions is caused by insufficient diffusion. The EPMed Ti–46Al–4Nb–0.1B alloy has a relatively low thermal deformation activation energy ( Q , 410 kJ mol −1 ), showed a well hot workability. The existence of the β phase is advantageous to harmonize the deformation of α 2 /γ lamellar grains and to improve the deformability of the TiAl alloy. The subsequent heat treatment can eliminate the Nb‐enriched regions and the B2 phase to ensure good service performance.