Controlled mechanical loading was applied to Ti-15Mo alloy during annealing at 550 °C. Massive formation of the
ωiso phase from the parent
β-phase occurred during annealing at 550 °C 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.