Investigation On The Fatigue Behavior Of A New Al Alloy And SiC_p/Al Composites Used For Piston

The new aluminum piston alloy developed by Xi'an Institute of Technology and its SiCp/Al composite fabricated by stirring cast process have been chosen as the experimental materials. The present study mainly deals with the fatigue behavior of the experimental materials at room temperature, 250℃and 350℃by INSTRON 1341 machine. Based on the test results, the morphologies of fatigue fractures at different temperatures have been analyzed by SEM in order to find the fatigue behavior and the micro-mechanism of the experimental materials and in particular, to focus on the effect of temperature and SiC particulate on the fatigue property of the materials.The results show that the mechanical properties of the new piston Al alloy and SiCp/Al composite is much superior to the common Al piston alloy, and SiC particles are distributed homogeneously in aluminum matrix and satisfied bonding. It has been found that the fatigue limit of Al alloy decrease remarkably with temperature increasing, but the fatigue property of SiCp/Al composite at 350℃is better than that at room temperature. The results also show that the addition of SiC particles will decrease the fatigue property of Al matrix at room temperature, but increase at 350℃.It is found that the creep character will be distinct for the Al piston alloy when the temperature is increased to 350℃and the cavities and micro cracks within the test materials along grain boundaries, which will be merged into the main fatigue cracks and increased the velocity of crack initiation and propagation, as consequence, the fatigue property at high temperature of Al alloy will be dropped rapidly. As far as SiC_p/Al...