Mesoscale modeling of dislocation density gradients and microstructure evolution

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Summary, in English

The presence of grain boundaries in the microstructure of metallic materials causes heterogeneous distributions of dislocation density. In the present contribution, the evolution of dislocation density is viewed as a reaction-diffusion system, involving mobile and immobile dislocations. Gradient effects are introduced by making the immobilization of dislocations sensitive to presence of grain boundaries. The model provides a macroscopic yield stress behavior of Hall-Petch type, without explicitly incorporating a yield stress dependence on the grains size. In addition, the model is employed in a cellular automaton algorithm, allowing a polycrystalline microstructure to evolve due to dynamic recrystallization, confirming that the introduced gradients provide important additions to recrystallization modeling.

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