Bellon Lab Tour

My research program is mainly focused on alloys or mixtures submitted to a sustained external forcing: such conditions are often met during either the processing of materials (e.g. by ball-milling or during thin film growth) or during the use of these materials (e.g. during frictional wear or under irradiation). Alloys in such environments have been termed "driven alloys." When the intensity of the forcing is high enough, non-equilibrium phases or microstructures can develop. From a practical point of view, these driving forces can have deleterious effects on the properties of materials: for instance precipitates can be dissolved,leading to a loss of mechanical strength. On the other hand, non-equilibrium processing can provide new routes to synthesizing novel materials: e.g., extended solid solutions or functional nanocomposites can be obtained by processing powders with high-energy ball milling or by processing thin films with energetic ion beams.

The related facet of our research is on the kinetic evolution of alloys during heat treatments. We are taking advantage of the kinetic models developed for driven alloys to study diffusion phenomena and diffusion-controlled reactions such as nucleation, growth and coarsening in complex alloys.

We are performing experiments, atomic computer simulations (kinetic Monte Carlo and molecular dynamics) and analytical modeling of these nonequilibrium alloys. The experiments carried out in our laboratory include ball-milling, wear testing, ion and laser irradiation (in collaboration with Prof. Averback). Materials are characterized by using the facilities available at the National User Facility at the Materials Research Laboratory. These include SEM, TEM, HRTEM, DSC and X-ray diffraction. Computer simulations are run on our cluster of LINUX workstations, and at computation centers on campus (MRL-MCC, MRL-CFC).