My talk will consist in two separate parts. The first part will focus on the coarsening of connected structures by surface diffusion. Nanoporous and microporous materials are of great interest in a number of applications ranging from battery anodes to captors and capacitors. When surface diffusion is thermally activated, these porous microstructures evolve in time, leading to a decrease of their surface area and a drop of the properties of the materials. Using a phase-field model for surface diffusion, we have investigated the coarsening behavior taking place during the evolution of these structures. More specifically, we have looked in details into the interactions between the morphological and topological characteristics of these structure during their evolution. The role of surface anisotropy on the coarsening kinetics have also been investigated.
The second part of my talk will focus on the thermal fluctuations of dislocations. The plastic behavior of metals and alloys are mostly controlled by the displacement of linear defects called dislocations. However, the behavior of these defects in temperature remains partially knows due to the complexity of the strain field generated in their vicinity. We have recently derived an analytical solution for the energy of a weakly perturbed dislocation., allowing us to characterize analytically the thermal fluctuations of dislocations. This analytical description matches remarkably well the fluctuation spectrum obtained from large scale molecular dynamics simulations, showing the validity of our approach. This new model also opens the way to develop analytical treatment for various problems involving thermally activated dislocation movement (cross-slip, kink pair formation, obstacle bypassing,…)