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

The correlation between the local structure and stability of supercooled liquid state is investigated in the Zr₇₀(Ni, Cu)₃₀ binary and Zr₇₀Al₁₀(Ni, Cu)₂₀ (numbers indicate at.%) ternary metallic glasses. The Zr₇₀Ni₃₀ binary amorphous alloy with a low stability of supercooled liquid state has a tetragonal Zr₂Ni-like local structure around Ni atom. Meanwhile, the Zr₇₀Cu₃₀ binary metallic glass has a different local structure of tetragonal Zr₂Cu, 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 Zr₂Ni-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.