Effect of high-pressure torsion process on precipitation behavior of α Phase in β-Type Ti-15Mo alloy

Abstract

Precipitation behavior of α phase in Ti-15Mo alloy during isothermal aging after straining by high-pressure torsion (HPT) was investigated and compared with that without HPT process. Upon isothermal aging, ultrafine equiaxed α phase particles and acicular α phase plates were obtained in HPT-processed samples, while only the coarse acicular α phase plates were obtained in the samples without HPT process. The precipitation of equiaxed α phase occurred faster than the precipitation of acicular α phase in HPT-processed samples. It seemed that a high density of dislocations resulted in highly strained area and enhanced atomic diffusivity, promoting the formation of equiaxed α phase. The HPTprocessed samples exhibited higher hardness and ultimate tensile strength but lower ductility than those of the specimens without HPT process. © 2014 The Japan Institute of Metals and Materials.