ATOMISTIC SIMULATION ON THE STRUCTURE AND MECHANICAL RESPONSE OF Σ3, Σ5 TILT GRAIN BOUNDARIES UNDER TENSION

Atomistic simulations are carried out on a serials of symmetric and asymmetric Sigma 3 [1 1 0] and Sigma 5 [0 0 1] grain boundaries (GBs) of Cu to investigate their structures and mechanical response under tension. The equilibrium 0K GB structures are generated by molecular statics simulation. It is found that Sigma 3 and Sigma 5 asymmetric GBs with different inclination angles are composed of only two structural units which are corresponding to their symmetric GBs. Molecular dynamics simulations are performed by applying a constant tensile strain on the bicrystal model with different Sigma 3 and Sigma 5 GBs. Simulation results show that the maximum tensile strength of the symmetric Sigma 3 and Sigma 5 GBs are higher than their asymmetric GBs, suggesting the symmetric GBs may have a more stable boundary structures.