Correlation between local structure and stability of supercooled liquid state in Zr-based metallic glasses

Abstract

The correlation between the local structure and stability of supercooled liquid state is investigated in the Zr 70(Ni, Cu) 30 binary and Zr 70Al 10(Ni, Cu) 20 (numbers indicate at.%) ternary metallic glasses. The Zr 70Ni 30 binary amorphous alloy with a low stability of supercooled liquid state has a tetragonal Zr 2Ni-like local structure around Ni atom. Meanwhile, the Zr 70Cu 30 binary metallic glass has a different local structure of tetragonal Zr 2Cu, where we suggest the icosahedral local structure by the quasicrystallization behavior in addition of a very small amount of noble metals. The effect of Al addition on the local structure in the Zr–Ni alloy is also examined. We have investigated that the dominant local structure changes in the icosahedral-like structure from the tetragonal Zr 2Ni-like local structure by the Al substitution with Ni accompanying with the significant stabilization of supercooled liquid state. It is concluded that the formation of icosahedral local structure contributes to the enhancement of stability of supercooled liquid state in the Zr-based alloys.