Coupled misorientation and solute segregation effects on dislocation nucleation from grain boundaries in Al alloys

Understanding the coupling effect of misorientation and solute segregation on dislocation nucleation from grain boundaries (GBs) is important for designing nanocrystalline metals. By molecular dynamics simulations, we demonstrate the segregation behavior of the solutes Cu and Mg in Al alloys and its relationship with GB dislocation nucleation. For low-angle GBs, solute Cu can inhibit dislocation nucleation more significantly than Mg, which is closely related to the effect of solute addition on the stacking fault energy. For high-angle GBs, local distortions caused by solute segregation enable dislocation nucleation at stress concentrated GB regions, leading to similar or reduced dislocation nucleation stresses.