Solute effects on dislocation glide in metals

Abstract

We examine theoretically the impact of dissolved solute atoms on the motion of dislocations in metals and, hence, on their plastic response. Two regimes of behavior are distinguished; a low velocity regime, in which the dislocation drags a near equilibrium solute cloud, and a high velocity regime, in which the dislocation is alternately trapped and free running. In both regimes, the overdamped motion of a dislocation in the alloy is exactly as it would be in the pure system but with regime-dependent dislocation mobilities. In the low velocity regime, the forces between dislocations are replaced by forces between dislocation-solute cloud “quasiparticles.” This paper provides analytical estimates for the mobilities in the two regimes, as well as expressions for calculating quasiparticle interactions. Finally, a prescription is provided for carrying out dislocation dynamics simulations without explicitly incorporating solute degrees of freedom.