Neutron diffraction measurement of the internal stresses following heat treatment of a plastically deformed Al/SiC particulate metal–matrix composite

The generation of internal misfit stresses between matrix and reinforcement has been studied in an Al/SiC particulate-reinforced metal-matrix composite. Bars of the composite were deformed in bending to introduce a varying residual stress field, and subsequently heat treated at different temperatures and for different times to study the evolution of the macroscopic stress field and the interphase stresses. The results show that the shape misfit stresses between the matrix and reinforcement, which arise from the difference in thermal expansion coefficient between the two phases, are reduced by the plastic deformation, but is re-generated by heat treatment. Higher temperatures and longer times increase the degree to which the shape misfit stresses return to their initial values. The re-generation of the shape misfit stresses is accompanied by a reduction in the variation of the macrostress field induced by the plastic bend.