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Indexed by:期刊论文

Date of Publication:2021-03-05

Journal:ADVANCED ENGINEERING MATERIALS

Volume:23

Issue:1

ISSN No.:1438-1656

Key Words:beta-elemental powder metallurgy; heat treatment; hot workability; TiAl

Abstract:TiAl-base alloys are a kind of promising materials for high-temperature applications. The beta phase existing in TiAl alloy can improve the hot workability, but deteriorates the creep properties. Preparing a beta phase-containing TiAl-base alloy to enhance the hot workability before hot deformation and eliminating the beta/B2 phase by postheat treatment to improve the service performance is a good strategy. Herein, a significant volume fraction of beta phase is obtained in the Ti-46Al-4Nb-0.1B alloy by the elemental powder metallurgy (EPM), and the beta/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 alpha(2)/gamma lamellar colonies, equiaxial gamma grains, and some randomly distributed beta phase and sigma-Nb2Al phase. The beta/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 beta phase is advantageous to harmonize the deformation of alpha(2)/gamma 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.