Formation of metastable phases and their effect on the glass-forming ability of Cu-Hf binary alloys

In this work, the glass-forming ability (GFA) of Cu-Hf binary alloys was systematically studied and some metastable phases were observed in the rapidly quenched samples. The microstructure of a Cu50Hf50 as-cast rod between the surface and the central region was carefully examined, and the composition of the unknown metastable phase was identified to be about Cu 42Hf58. The formation mechanism of metastable phases and their effect on the GFA of Cu-Hf binary alloys was also investigated. Taking the metastable phases into account, the parameter γ* was revised, and its prediction of the GFA of Cu-Hf binary alloys was found to be roughly in accordance with the experimental results.