Correlation between atomic-level structure, packing efficiency and glass-forming ability in Cu-Zr metallic glasses

The local structure and atomic packing in CuxZr100 − x (46 ≤ x ≤ 70) alloys have been investigated using classical molecular dynamics. We convincingly demonstrate that the atomic packing efficiency of the polytetrahedral clusters strongly correlates with the glass-forming ability. It is found that the full-icosahedra (< 0,0,12,0 >), which is considered to be a key local structural feature associated with the glass formation in metallic alloys, alone cannot explain the compositional dependence of glass-forming ability. We suggest that the population of the so-called defected icosahedra (< 0,2,8,2 >), apart from the full-icosahedra, could be crucial to account for the observed high atomic packing efficiency in the best glass-forming compositions.