Hf–Cu–Ni–Al bulk metallic glasses: Optimization of glass-forming ability and plasticity

In the Hf–Cu–Ni–Al quaternary system, the Hf51Cu27.75Ni9.25Al12 bulk metallic glass (BMG) exhibits the best combination of the large glass-forming ability (GFA) and compressive plasticity. Minor substitution of Nb for Hf in Hf–Cu–Ni–Al BMGs degrades not only the GFA but also plasticity, while the substitution of Ta does not have an appreciable effect on both properties. For the investigated Hf-based BMGs, the shear modulus G is a more sensitive indicator to correlate with their plasticity than the Poisson′s ratio. Meanwhile, the correlation between the G and the glass transition temperature Tg for the Hf-based BMGs can be expressed as G = 9.9 + 576 (Tg/Vm)[1 − 4/9(T/Tg)2/3].