Experimental study on low-cycle fatigue behaviours of the specimen consisting of the composites (Al-12Si/ABOw) and matrix Al-12Si alloys

The low-cycle fatigue tests of the specimen, which was composed of half composites reinforced by aluminium borate whisker (ABOw) and half unreinforced matrix alloys, were performed under different temperatures. The results showed that the specimen exhibited obvious cyclic hardening at low temperature while increasingly remarkable cyclic softening with the increase of temperature. Meanwhile, the micromorphology of the fracture surface revealed apparent brittle characteristics at low temperature but dominated ductile characteristics at high temperature. The analysis of curves of total strain amplitude versus fatigue life indicated that the dominant fatigue damage mechanism changed from the elastic damage to the plastic damage with the increase of total strain amplitude. In addition, the description of fatigue behaviours based on energy criterion suggested that the capacities of specimen to absorb and dissipate plastic strain energy improved with increasing of temperature but may also be weakened by the strengthening effect of composite part.