Energy-releasing and phase transitions of Ti-based bulk metallic glass composites during heating

Abstract

The energy-releasing and phase transitions of Ti-based bulk metallic glass composites (BMGCs) during heating largely remain elusive. Here, the effects of cooling rates and compositional changes on energy-releasing and phase transitions of two BMGCs containing relatively stable β-Ti crystals or metastable β-Ti crystals are investigated. With decreasing the cooling rates, both BMGCs transform from non-equilibrium BMGCs to quasi-equilibrium BMGCs. Moreover, decreasing the Co content reduces the phase stability of β-Ti. DSC heating, isothermal ω-Ti precipitates in β-Ti crystals before Tg, and as the temperature above Tx, the glass matrix undergoes crystallization. With decreasing the cooling rates, both the relaxation and crystallization enthalpies decrease, but which can be significantly enhanced by decreasing the Co content, suggesting that BMGCs with unstable β-Ti dendrites are of better energy-releasing properties. These findings not only reveal the energy changes and phase transitions of BMGCs during heating, but also promote their practical applications as energy-releasing materials.