Microstructure and mechanical properties of AA7039+20%SiC W composite

Hot deformation tests were performed on an AA7039-matrix composite reinforced with a 20% addition of SiC whiskers. The flow stress maximum was reduced with deformation temperature from 640 MPa to approximately 8 MPa at 293 K and 823 K, respectively. TEM observations, performed on as deformed samples, revealed a highly recovered substructure of the matrix and a striated structure of the whiskers. The fringes, which are perpendicular to the whiskers' longitudinal axis, were ascribed to nano-sized twins and stacking faults formed during the crystal growth rather than to some effects of the deformation process.