Effect of #beta# Phase Stability on Mechanical Properties in a #beta#-Rich #alpha# + #beta# Type Titanium Alloy

摘要

An unstable #beta# phase in titanium alloys can transform into martensite during deformation resulting in the well-established tensile characteristics, i.e. low yield stress, excellent ductility and high work hardening rate. The effect of unstable #beta# phase on fracture toughness of titanium alloys, however, is not clear yet. The unstable #beta# phase was reported to increase both static and dynamic fracture toughness in some commercial titanium alloys. On the contrary, the unstable #beta# phase was reported to decrease dynamic fracture toughness of Ti-6Al-4V alloy. In order to make clear such contradiction, the stability of #beta# phase in a #beta#-rich #alpha# + #beta# type titanium alloy, Ti-4.5Al-3V-2Mo-2Fe, and its relationship with mechanical properties, in particular, fracture toughness of the alloy were investigated. The change of #beta# phase stability was determined from the change of its lattice parameter.