Study of structural anisotropy in Cu_(50)Zr_(45)Al_5 metallic glass under uniaxial compression by molecular dynamics simulations

摘要

The structural anisotropy in Cu_(50)Zr_(45)Al_5 metallic glass under uniaxial compression from zero up to 1800 MPa was studied by molecular dynamics simulations. The anelastic strain is found to be negligibly small below 600 MPa whereas it increases with the simulation time from 600 to 1200 MPa. The degree of structural anisotropy and the atomic structure were characterized using a second order fabric tensor and Voronoi tessellation, respectively. Structural analysis indicates that the anelastic deformation occurs via the destruction of clusters with high geometric symmetry. It is found that the degree of anisotropy increases with the applied loads almost linearly whereas is nearly invariant under constant loads below 1400 MPa. Comparing with our previous results, the degree of anisotropy in Cu_(50)Zr_(45)Al_5 MG is about 20 —30% lower than that in Cu—Zr MGs under similar loading conditions. It indicates that the covalent bonding around Al atoms tends to stabilize the local structure against anelastic deformation in Cu_(50) Zr_(45)Al_5 metallic glass.