Atomic structure of biodegradable Mg-based bulk metallic glass

Abstract

We have used highly accurate first-principles molecular dynamics simulations to elucidate the structure of Mg₆₀Zn₃₅Ca₅ and Mg₇₂Zn₂₃Ca₅ bulk metallic glasses, which are candidate materials for biomedical implants; these two compositions exhibit different behaviours when implanted. The environments of each species are different, and average coordination numbers are ∼13 for Mg, ∼11 for Zn and ∼18–19 for Ca. A wide range of local environments were found and icosahedral motifs, often seen in bulk metallic glasses, were among the most common for both Mg and Zn. Through the computation of a chemical short-range order parameter, a moderate avoidance of Zn–Zn bonding over Zn–Mg or Zn–Ca was observed. No statistically significant difference in structure was observed between the two compositions.