First-principles calculations of atomic stress in CuZr metallic glass under shear strain

Lobzenko, I.   ; Tsuru, Tomohito   ; Shiihara, Yoshinori*; Iwashita, Takuya*

Revealing the origin of the mechanical properties of metallic glasses (MG) is a long-standing problem. MGs respond to the external strain with the activation of collective atomic motion, but the triggers of such motions are not revealed yet, in contrast to the well-defined dislocations in crystals. To study this collective atomic response in detail, we use the atomic stress calculations in the first-principles framework. Four small random Cu50%Zr50% structures were prepared and put under the strain from 0.5 to 8.0%. The stress response is shown separately for Cu and Zr. We analyze the system's transformation between the affine and relaxed states and find a significant deviation from elastic behavior. As the atomic von Mises stress change indicates, the xy shear strain invokes atomic stress response in other shear components. Other local parameters, such as charge transfer, atomic displacements, and atomic strain, are also discussed.