Theoretical study on the composition location of the best glass formers in Cu-Zr amorphous alloys.

This study combines the molecular dynamics (MD) simulations and first-principles approach to explain the experimental observation that the best glass formers of Cu-Zr bulk metallic glasses (BMGs) have the compositions Cu50Zr50 and Cu64Zr36. These two best glass formers are first calculated to be most abundantly composed of Cu6Zr7 and Cu8Zr5 icosahedral clusters when compared in the compositional range of CuxZr100-x (45 ≤ x ≤ 70), and then these two icosahedral clusters are calculated to have the lowest formation energy among the icosahedral clusters CuxZr13-x (3 ≤ x ≤ 10), as well as possessing some characteristics in electronic structure and chemical hardness. Through understanding the properties of specific icosahedral clusters in metallic glasses, the structural and energetic contribution to the glass-forming ability are systematically discussed.