We studied the glass forming ability (GFA) of Cu-rich Cu–Hf binary alloys and found that some of the alloys can be prepared as bulk metallic glasses with maximum diameter up to 2 mm by a conventional Cu-mould casting. The best glass former within the compositional range studied is off-eutectic Cu65Hf35 alloy, which is markedly different from the prediction from the multicomponent and deep eutectic rules. The GFA, thermal stability, kinetics of the glass transition and crystallization for Cu65Hf35 glassy rods were studied. The glass formation mechanism for binary Cu–Hf alloys was investigated from the thermodynamic point of view. It is suggested that the better GFA of off-eutectic Cu65Hf35 alloy could be due to its higher value of the parameter γ*, which is defined as the ratio between the driving force for glass formation and the resistance of glass formation to crystallization.

Long-term thermal stability of Nd60Al20Co20 bulk metallic glass (BMG) with excellent glass forming ability was investigated by Kissinger and Vogel-Fulcher-Tammann (VFT) analyses, respectively. The heating rate dependence of crystallization temperature of the BMG was found to follow the VFT nonlinear relationship rather than Kissinger’s linear fittings. It is suggested that the continuous heating crystallization diagrams obtained from VFT equation should be more adequate to estimate the long-term thermal stability of Nd60Al20Co20 bulk metallic glass according to the time-temperature-transformation diagram based on isothermal annealing.

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