Homogeneous shear-driven reversible α-to-α″ phase transformation and superelasticity of titanium investigated by molecular dynamics simulations

Shear is one of the most fundamental deformation modes in solid-state phase transitions and greatly influences the transformation process and mechanism. We employed molecular dynamics simulations to investigate the reversible α-to-α″ phase transitions driven by homogeneous shear at different temperatures from 200 to 500 K. The simulation results clarified the phase transformation mechanism and its reverse transformation mechanism as well as the associated crystallographic orientation relationships. The transformation mechanism is analogous to the reorientation of α-Ti upon shock loading either experimentally or in a simulation, manifesting the validity of our simulation results. The reverse transformation mechanism indicates two transformation paths that vary with temperature, leading to two types of stress–strain curves upon unloading. The stress–strain relationships at different temperatures reveal superior superelasticity at low temperatures (200–300 K) and inferior superelasticity at high temperatures (350–500 K). The temperature effect on the shear-induced phase transition and superelasticity was also elucidated. The simulation results provide new insights into the stress-induced phase transition and superelasticity of Ti.