Atomic structure of biodegradable Mg-based bulk metallic glass

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 [similar]13 for Mg, [similar]11 for Zn and [similar]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.