Thermal Stability and Kinetics of Binary Cu₆₅Hf₃₅ Bulk Metallic Glass

We investigate the thermal stability and kinetics of Cu₆₅Hf₃₅ bulk metallic glass (BMG). Cu₆₅Hf₃₅ glassy rods in diameter up to 2mm are prepared by a conventional copper mould suction casting. Kinetics of glass transition and crystallizations are investigated and the ideal glass transition temperature of the alloy is obtained. It is found that the dependence of crystallization temperature of the BMG on the heating rates follows the Vogel--Fulcher--Tammann (VFT) non-linear relationship rather than the Kissinger and Lasocka linear fittings. The long-term thermal stability of the BMG is investigated by means of continuous crystallization diagrams obtained from the extension of VFT analysis. It is suggested that ideal glass transition and crystallization temperatures can also be regarded as the long-term stability criteria of the BMG.