Mesoscale Defect Motion in Binary Systems: Effects of Compositional Strain and Cottrell Atmospheres

TL;DR

This paper develops an analytical model for dislocation velocity in binary systems, incorporating effects of solute segregation and Cottrell atmospheres, and verifies predictions with numerical simulations.

Contribution

It introduces a mesoscopic phase-field crystal model to predict defect dynamics influenced by compositional stresses and atmospheres, advancing understanding of defect motion.

Findings

Dislocation glide paths can be deflected by Cottrell atmospheres.

Climb speed and direction are affected by solute concentration.

Defect annihilation can be altered or prevented by compositional effects.

Abstract

The velocity of dislocations is derived analytically to incorporate and predict the intriguing effects induced by the preferential solute segregation and Cottrell atmospheres in both two-dimensional and three-dimensional binary systems of various crystalline symmetries. The corresponding mesoscopic description of defect dynamics is constructed through the amplitude formulation of the phase-field crystal model which has been shown to accurately capture elasticity and plasticity in a wide variety of systems. Modifications of the Peach-Koehler force as a result of solute concentration variations and compositional stresses are presented, leading to interesting new predictions of defect motion due to effects of Cottrell atmospheres. These include the deflection of dislocation glide paths, the variation of climb speed and direction, and the change or prevention of defect annihilation, all of which play an important role in determining the fundamental behaviors of complex defect network and dynamics. The analytic results are verified by numerical simulations.