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Date of Publication:2022-10-10

Journal:Cailiao Yanjiu Xuebao/Chinese Journal of Materials Research

Volume:35

Issue:10

Page Number:741-751

ISSN No.:1005-3093

Abstract:Ti-6Al-4V alloy is widely used in laser solid forming, however, low work-hardening ability and ductility limit its industrial applications. In this paper, a novel Ti-4.13Al-9.36V (%) alloy with cluster composition of 4[Al-Ti12](AlTi2)+12[Al-Ti14](V2Ti) was designed based on the cluster composition formula 12[Al-Ti12](AlTi2)+5[Al-Ti14](V2Ti) of Ti-6Al-4V. Samples of two alloys Ti-4.13Al-9.36V and Ti-6.05Al-3.94V (set as contrast alloy) were prepared by laser solid forming and followed by heat treatment. Then the microstructure and mechanical properties of the as-deposited and solution treated alloys were investigated. The results show that the microstructure of the as-deposited alloys Ti-4.13Al-9.36V and Ti-6.05Al-3.94V consists of columnar prior-β grains, which grow epitaxial from the substrate along the deposition direction. A basket-weave α-laths existed in the inner prior-β grains. The width of prior-β grains and the width of α-laths of Ti-4.13Al-9.36V alloy are ca 606 μm and 0.48 μm, in the contrast, those of Ti-6.05Al-3.94V alloy are ca 770 μm and 0.71 μm, respectively. Further, after the Ti-6.05Al-3.94V subjected to post solution treatment at 920℃ for 2 h followed by water cooling, its microstructure consists of phases α'+α, and the corresponding yield strength, ultimate tensile strength and ductility to failure were ca 893 MPa, 1071 MPa and 3%, respectively. However, when the Ti-4.13Al-9.36V subjected to post solution treatment at 750℃ for 2 h followed by water cooling, its microstructure consists of phases α''+α, and the related yield strength, ultimate tensile strength and ductility to failure were ca 383 MPa, 989 MPa and 17%, respectively. This may be ascribed to that the stress-induced α''-phase could significantly improve the work-hardening ability compared with α'-phase. The work-hardening ability and ductility of the Ti-alloy used for laser solid forming could be significantly improved by adjusting the microstructure with phases α''+αvia cluster-plus-glue atom model. © 2021, Editorial Office of Chinese Journal of Materials Research. All right reserved.

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