Molecular Dynamics Simulations on Mechanical Properties of Substrate Cu with Impurity Ni

The mechanical properties of Cu/Ni film composed of substrate Cu and impurity Ni, and the influence of impurity sizes and shapes on yield strength was studied under tensile loading. Based on the embedded-atom-method potential, molecular dynamics simulations were carried out to analyze the interactions between the impurity and dislocations. The results show that the introduction of impurity Ni decreases the yield strength of the nano-crystalline. However, the impurity hinders the movement of dislocations because of the interface between Cu and Ni, and it strengthens the substrate due to the strong interaction force of Ni in the plastic deformation stage. The films with the shape of square, transverse rectangular, circular and vertical rectangular impurities have similar yield strengths at the cross-sectional size 6.9nm2; if the cross-sectional size is 15.7nm2, the film with transverse rectangular impurity has the largest yield strength 7.41MPa; at the cross-sectional size 3.1nm2, film with circular impurity ha