Stress-induced phase transformations in Ti-15Mo alloy at elevated temperature

• Stress-induced phase transformations in Ti-15Mo alloy were investigated at 550 °C. • Plastic deformation promotes the β → α transformation in deformed sample. • Deformed sample contains large number of very small (less than 100 nm) α particles. • Refined α + β microstructure exhibit the highest microhardness of 398 HV. Controlled mechanical loading was applied to Ti-15Mo alloy during annealing at 550 °C. Massive formation of the ω iso phase from the parent β-phase occurred during annealing without external stress or with stress well below the yield stress. Moreover, a massive α phase precipitation takes place under simultaneous annealing and plastic deformation. Plastic deformation plays a key role in β → α transformation and achieving refined α + β type microstructure resulted in improved mechanical properties. Studying phase transformations during plastic deformation is critical for understanding and optimizing thermomechanical processing of metastable β-Ti alloys.