THERMOMECHANICALLY INDUCED RESIDUAL STRAINS IN AL SICP METAL-MATRIX COMPOSITES/

Residual lattice strains in the aluminium and SiC phases of F3S.20S ex truded A359 20% SiC metal-matrix composite were measured by using neut ron diffi action at room and elevated temperatures to monitor the effe cts of in situ uniaxial plastic deformations. The results are interpre ted with reference to the thermomechanical history of the specimens. T he compressive strain at yield due to thermal expansion mismatch strai ns and uniaxial deformation was found to be identical over the tempera ture range 100250 degrees C. The separation of the aluminum compressiv e and tensile strain yield loci were found to be 45 x 10(-4) at 50 deg rees C, 4.1x10(-4) at 100 degrees C and 2.5x10(-4) at 250 degrees C. T he temperature dependence of the separation of the loci was found to a gree closely with the temperature dependence of the! macroscopic flow stress. (C) 1998 Elsevier Science Ltd. All rights reserved.