Correlation between the Local Atomic Structure of Melts and Glass Forming Ability in Zr-Cu-Ni-Al Alloys

The correlation between the atomic structure of melts and glass forming ability (GFA) in Zr₅₃Cu_18.7Ni₁₂Al_16.3 and Zr_50.7Cu₂₈Ni₉Al_12.3 (abbreviated as Zr53 and Zr507, respectively) alloys are studied by first principle simulations. The topological structure can be described by the Al-centered Kasper polyhedra and other distorted clusters with extrinsic disclinations. Due to the lower Al content in the Zr507 melts, its number of icosahedra is larger than that of the Zr53 melts. Also, the icosahedra in the Zr507 melts possess smaller distortion than those of the Zr53 melts, making the icosahedra more stable in the Zr507 melts. These two structural differences contribute to the slow dynamics and further enhance the GFA in the Zr507 alloy.