The relation of mechanical properties and local structures in bulk Mg ₅₄(Cu_1-xAg_x)₃₅Y₁₁ metallic glasses: Ab initio molecular dynamics simulations

Understanding the correlation of deformation and local structures in bulk metal glasses (BMGs) is essential for the developing new types of amorphous alloys and their engineering applications. We investigate the relation of local structures and mechanical properties for Mg₅₄(Cu_1-xAg _x)₃₅Y₁₁ (0 < x ≤ 0.5) alloys by combining ab initio molecular dynamics simulations with density functional theory calculations. It is found that local structures defined by the common-neighbor analysis and mechanical properties display a development as a function of composition, and the calculated results with respect to the Ag composition is well consistent with experiments. We show a strong interplay between local structures and mechanical properties in that high icosahedral ordering and low free volume are helpful to improve the strength, while the incorporation of crystalline ordering and high free volume can initiate a better intrinsic plasticity. Physical implications of these results are discussed and our research is of great value to the development of multi-components amorphous alloys.