Modification of dislocation emission sources at symmetric tilt grain boundaries in Ag by Cu solute atoms

•MD simulation shows that Cu modifies the dislocation nucleation from a GB in Ag.•Even small addition of solutes increases the yield stress at some concentrations.•Addition of new solutes does not change the yield stress at other concentrations.•The solute effect strength varies because they segregate at the different sites. A very small amount of immiscible solutes can dramatically decrease the ability of dislocations to nucleate from grain boundaries. In this paper we report the results of the molecular dynamics simulations which show that at larger concentrations, the solute effect becomes rather non-trivial: there are concentration ranges where even small addition of solutes considerably suppresses the dislocation nucleation from grain boundaries and there are concentration ranges where addition of new solutes almost does not change the dislocation nucleation ability. We reveal the atomic mechanism of these effects.