\title{Effect of Solutes on Dislocation Motion\\
 ----- A Phase-Field Simulation}

\author{S.Y. Hu,Y.L. Li, Y.X. Zheng$\dag$, and L.Q. Chen\\
Department of Materials Science and Engineering\\
The Pennsylvania State University, University Park, PA 16802, USA\\
$\dag$ Department of Mathermatics\\
The Pennsylvania State University, University Park, PA 16802, USA}


Based on recent advances in phase-field models
for integrating phase and defect microsturctures as well as for
dislocation dynamics, the interactions between diffusional solutes
and moving dislocations under applied stresses are studied in
three dimensions.  A new functional form for describing the
eigenstrains of dislocations is proposed, eliminating the
unphysical dependence of the magnitude of the dislocation Burger's
vector on the applied stress and providing correct stress fields
of dislocations. The operation of Frank-Read source in the
presence of diffusional solutes, the effect of chemical potential
of solid solution on equilibrium distributions of Cottrell
atmospheres, and drag effect of Cottrell atmospheres on
dislocation motion are examined. The results demonstrate that the
phase-field model developed correctly describes the long-rang
elastic interactions and short-rang chemical interactions that
control dislocation motion.