Skip over navigation

 

Climb Enabled Discrete Dislocation Plasticity of Particle Reinforced Composites

Can Ayas (Cambridge University), Vikram Deshpande (Cambridge University)

Discrete Dislocation Plasticity

Tue 9:00 - 10:30

RI Hall 108

With the exception of single crystals, all metals inherently deform non-homogeneously in the plastic regime since the constituents of the microstructure does not slip with equal ease. The gradients of plastic deformation require the storage of geometrically necessary dislocations contributing to the overall strain hardening. This gives rise to a plastic response depending on the relevant microstructural length scale of the material. In this study we investigate the plasticity size effects in particle reinforced metal matrix composites. We use a planar climb enabled discrete dislocation plasticity framework where the dislocation motion is coupled with the vacancy diffusion and study the plastic deformation and evolving dislocation structure in composites while changing particle size, reinforcement morphology and climb mobility. In the light of this systematic parametric study, we predict and explore the high temperature deformation mechanisms in composites in comparison with the glide only deformation mode observed at the room temperature. Our simulation results revealed that a distinct size effect is seen for glide only deformation with smaller being harder while size effects are less pronounced upon increasing the climb mobility. We show that this is due to i) absence of pile-ups and hence an increase in the amount of plastic slip and ii) dislocation climb motion create/annihilate vacancies in the crystal which triggers a vacancy diffusion and hence a mass transport inside the material in climb enabled simulations. The reinforcement morphology has a negligible effect on the plastic hardening behaviour for glide only deformation mode whereas in climb assisted glide a softer response is attained upon reducing the overlap between the reinforcing particles while keeping their volume fraction fixed.