A phase-field dynamic model was developed and used to investigate the effects of dislocations and applied strain upon the precipitation behaviour and microstructural evolution of model binary alloys. The simulations showed that the local microstructure depended not only upon the relative magnitude of the dislocation stress and the stress induced by the applied strain, but also upon the composition and magnitude of the stress. It was also shown that the applied strain made the phase decomposition quicken. The results suggested that the microstructure of an alloy and its evolution could be controlled by finding a suitable combination of dislocations, applied strain and composition, and that theoretical calculations were helpful in predicting what those combinations should be. The simulations showed that an applied tensile strain elongated the precipitates, and that the elongation direction was perpendicular to the applied strain direction for soft precipitates; even if dislocations existed. Although the precipitates nucleated in tensile-stress regions of the dislocations and dislocation walls, the orientation and the local morphology of the precipitates at the dislocation regions depended upon the relative magnitudes of the applied and dislocation stresses. As the alloy concentration increased, the precipitate morphology changed from a separated elliptical shape to a band shape under the applied strain. Finally, the applied strain made the phase decomposition faster as the alloy concentration decreased.

Phase Field Simulation of Precipitates Morphology with Dislocations Under Applied Stress. Y.Li, Y.Yu, X.Cheng, G.Chen: Materials Science and Engineering A, 2011, 528[29-30], 8628-34