Coupling effect of deformation mode and temperature on tensile properties in TWIP type Ti–Mo alloy

The coupling effect of deformation mode and deformation temperature from 298 K to 673 K on tensile properties was systematically studied in a Ti–15Mo alloy with {332}<113> twinning-induced plasticity (TWIP) effect and a comparison material of Ti–15Mo–1Fe alloy deformed by dislocation slip. The yield strength remained relatively constant in Ti–15Mo alloy, while it monotonously decreased in Ti–15Mo–1Fe alloy as increasing deformation temperature. Due to enhancement of β phase stability from ω phase precipitation, the {332}<113> twinning was suppressed and the contribution of dislocation slip to plastic deformation increased, which compensated the thermal softening effect in Ti–15Mo alloy. High strain hardening rate was induced in Ti–15Mo alloy at 298 K due to the dynamic Hall-Petch effect from amounts of {332}<113> twins and formation of abundant geometrically necessary dislocations (GNDs). As increasing deformation temperature, the suppression of dynamic Hall-Petch effect and GNDs formation as well as the enhancement of dynamic recovery rate of dislocations resulted in the continuous decrease in strain hardening rate.