Molecular dynamics simulation on the mechanical properties of Zr-Cu metallic nanoglasses with heterogeneous chemical compositions

The mechanical properties of metallic nanoglasses (NGs) strongly depend on the average size of glassy grains (D_avg). Nevertheless, current knowledge on the effects of sizes of glassy grains is incomplete for the mechanical properties of NGs. Herein, Zr_xCu_100-x (25 ≤ x ≤ 75) nanoglasses containing glassy grains with different chemical compositions, i.e., the heterogeneous NGs (HNGs), are investigated by molecular dynamics simulation, and the relation between ultimate tensile strength (UTS) and D_avg is determined. Specifically, the UTS decreases with decreasing D_avg in Zr-Cu HNGs when D_avg < 10 nm, mainly resulting from the increased volume fraction of glass-glass interfaces, while UTS would follow the Hall–Petch like relation for Zr-Cu HNGs when D_avg > 10 nm, which is closely related to glassy grains with compositions dominated by Zr atoms. This study provides a deep insight into the mechanical property dependence on grain size in the HNGs, which could be a novel strategy in resolving the issue of strength-ductility tradeoff in NGs.