Thermomechanically induced residual strains in [formula omitted] metal-matrix composites

Abstract

Residual lattice strains in the aluminium and SiC phases of F3S.20S extruded A359 20% SiC metal-matrix composite were measured by using neutron diffraction at room and elevated temperatures to monitor the effects of in situ uniaxial plastic deformations. The results are interpreted with reference to the thermomechanical history of the specimens. The compressive strain at yield due to thermal expansion mismatch strains and uniaxial deformation was found to be identical over the temperature range 100–250 °C. The separation of the aluminum compressive and tensile strain yield loci were found to be 4.5 × 10 −4 at 50 °C, 4.1 × 10 −4 at 100 °C and 2.5 × 10 −4 at 250 °C. The temperature dependence of the separation of the loci was found to agree closely with the temperature dependence of the macroscopic flow stress.