Relaxation of thermal mismatch stress due to plastic deformation in an Al/SiCp metal matrix composite

The neutron diffraction method was applied to determine the evolution of internal strains (and stresses) within an Al/SiCp metal matrix composite. The specimen was subjected to thermal treatment followed by different types of elastoplastic deformation. An Eshelby type model was used to study the contribution of different phenomena to the evolution of stress. The results of the experiment were compared with model predictions obtained using a self-consistent model of elastoplastic deformation. The validity of the use of this model for stress analysis was verified by comparison with a neutron diffraction measurement performed for an external load applied ‘in situ’. Hydrostatic phase stresses were experimentally found in the samples after thermal treatment. These stresses were modified due to plastic deformation, and significant relaxation of the microstresses was observed.