Document Type

Journal Article

Publisher

Elsevier Ltd

Faculty

Faculty of Health, Engineering and Science

School

School of Engineering

RAS ID

21201

Comments

Original published as : Liu, L. H., Yang, C., Kang, L. M., Long, Y., Xiao, Z. Y., Li, P. J., & Zhang, L. C. (2016). Equiaxed Ti-based composites with high strength and large plasticity prepared by sintering and crystallizing amorphous powder. Materials Science and Engineering: A, 650, 171-182. Original article available here

Abstract

High-performance titanium alloys with an equiaxed composite microstructure were achieved by sintering and crystallizing amorphous powder. By introducing a second phase in a β-Ti matrix, series of optimized Ti-Nb-Fe-Co-Al and Ti-Nb-Cu-Ni-Al composites, which have a microstructure composed of ultrafine-grained and equiaxed CoTi2 or (Cu,Ni)Ti2 precipitated phases surrounded by a ductile β-Ti matrix, were fabricated by sintering and crystallizing mechanically alloyed amorphous powder. The as-fabricated composites exhibit ultra-high ultimate compressive strength of 2585MPa and extremely large compressive plastic strain of around 40%, which are greater than the corresponding ones for most titanium alloys. In contrast, the alloy fabricated by sintering and crystallizing Ti-Zr-Cu-Ni-Al amorphous powder, which possesses significantly higher glass forming ability in comparison with the Ti-Nb-Fe-Co-Al and Ti-Nb-Cu-Ni-Al alloy systems, exhibits a complex microstructure with several intermetallic compounds and a typical brittle fracture feature. The deformation behavior and fracture mechanism indicate that the ultrahigh compressive strength and large plasticity of the as-fabricated equiaxed composites is induced by dislocations pinning effect of the CoTi2 or (Cu,Ni)Ti2 second phases and the interaction and multiplication of generated shear bands in the ductile β-Ti matrix, respectively. The results obtained provide basis guidelines for designing and fabricating titanium alloys with excellent mechanical properties by powder metallurgy.

DOI

10.1016/j.msea.2015.10.048

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