Mechanical properties of gradient metallic glass induced by spatially non-uniform dynamics

Abstract

We report a gradient metallic glass (MG) prepared based on stress driven spatially non-uniform dynamics. When elastostatic loading is applied to the MG with ultra-low aspect ratio, strongly lateral constraints can lead to a triaxial compressive stress region, resulting in a non-uniform stress field throughout the entire sample. Thereupon atoms in different regions of the sample will undergo asynchronous evolution, ultimately forming a gradient structure. The experimental results reveal that the energy state and mechanical properties of the gradient MG exhibit a gradient distribution. The molecular dynamics (MD) simulation indicates that triaxial compressive stress induces a quantity of uniform plastic events. Meanwhile, triaxial compressive stress also causes the changes of local atomic configurations: the decreases of the densely packed icosahedral clusters with high fivefold symmetry and of the potential barrier for plastic events. This work provides new insights for the macro heterogeneous design and the toughening of MGs.