Effects of Temperature on the Fatigue Characteristics of the Bond Zone between the Al-12Si/ABOw Composites and Al-12Si Alloys

The fatigue characteristics of the bond zone between the aluminum borate whiskers-reinforced aluminum matrix (Al-12Si/ABOw) composites and Al-12Si matrix alloys were investigated under different temperatures. The fatigue tests were controlled by constant load amplitudes with the test temperatures range from 25 to 350 °C. The microscopic fatigue characteristics of the bond zone were studied through SEM observation and fracture analysis. The effects of temperatures on the fatigue characteristics of the bond zone were discussed from two aspects of microstructure evolution and macroscopic mechanical simulation. The results showed that the fatigue cracks of specimens, which were consisted of Al-12Si/ABOw composites and Al-12Si matrix alloys, nucleated at casting defects in composites side of the bond zone, eutectic Si particles and interface between Al matrix and Si particles at 25, 200 and 350 °C, respectively. The Al matrix became softened rapidly with the increase in temperature, resulting in the change of the most severe stress concentration sites in the bond zone.