Plastic-strain cyclic response of SiC particulate reinforced aluminum composites

The cyclic stress response characteristics of several SiC particulate reinforced aluminum composites and their unreinforced counterpart at room temperature were investigated. The as-extruded specimens were cyclically deformed with fully-reversed loading under a range of constant plastic-strain amplitudes. The test results showed that the cyclic response characteristics of the reinforced and unreinforced materials were different. During most of the fatigue life, the unreinforced aluminum mainly exhibited cyclic hardening, while the composites showed gradual softening. The dislocation substructure developed during cyclic deformation was analyzed using transmission electron microscopy. The discrepency between the dislocation substructure obtained from processing compared to its development during cyclic strain loading is thought to give rise to the observed cyclic stress response behavior.