Glass-forming ability and thermal stability of a new bulk metallic glass in the quaternary Zr-Cu-Ni-Al system

A new quaternary Zr-based bulk metallic glass, Zr₅₁Cu _20.7Ni₁₂Al_16.3, was developed by using a newly proposed approach. It has shown that the reduced glass transition temperature, defined as the ratio of the glass transition temperature to the melting point temperature, of the new quaternary Zr-based bulk metallic glass is as high as 0.66. The Gibbs free energy difference between the glassy state and the corresponding equilibrium crystals is estimated to be 0.99 kJ/mol. The maximum diameter of the glassy rod-like sample prepared through conventional copper-mold casting is close to 5 mm. The single amorphous phase remains unchanged after holding at 400 °C for 60 min. These suggest this new alloy having a reasonable glass-forming ability and a high thermal stability against crystallization, promising a base composition for creating other Zr-based bulk glass formers.