Formation of Metastable Phases and Their Effect on the Glass-Forming Ability of Cu-Hf Binary Alloys

Abstract

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 Cu₄₂Hf₅₈. 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.