Résumé
Stress-relaxation mechanisms are regularly observed in amorphous systems, ranging from soft colloidal gels to hard metallic glasses. They are often characterized by hyper-diffusive particle displacements and compete with the spontaneous structural relaxations. Despite intense research is ongoing both experimentally and theoretically, their nature and properties at the microscopic length-scale remain elusive. For this reason, we want here to use Small Angle X-ray Photon Correlation Spectroscopy to study the dynamical signatures (length-scale dependence, degree of cooperativity) of the stress relaxation mechanisms in a colloidal glass as a function of the amount of residual internal stresses. This experiment will give a contribution to the understanding of the stress-related dynamical behaviours, frequently recognised in glassy systems but not yet fully clarified.