Phase transition and melting of titanium at high pressure-temperature conditions

Due to exceptional mechanical and thermal properties, behaviors of titanium (Ti) under high pressure-temperature conditions have been extensively studied. Upon compression, multiple phases of Ti are occurred via the martensitic phase transitions. The phase diagram up to 200 GPa and 3000 K was established. However, there is a lack of understanding of their stability and melting at elevated temperature-high pressure regime. Using quantum molecular dynamics simulations, we show that applying moderate temperatures on several Ti phases can result in either reconstructive or displacive phase transitions. Stronger heating leads to the formation of a new state before the melting takes place.