Influence of Low-Temperature Freezing Treatment on Micro-Area Hardness and Residual Stress of SiCp/Al Composites

In order to study the effect of freezing treatment on the mechanical properties of SiCp/Al composites, SiCp/Al composites were froze by liquid nitrogen for different time. The micro-area hardness, two-phase residual stress and interface combination status of were analyzed with micro hardness tester, x-ray diffractometer and SEM before and after freezing treatment. The results show that the hardness of Al matrix after freezing is higher than that of before freezing, while the hardness of SiC particles does not show much change. Low-temperature freezing makes the residual compressive stress of matrix phase and the residual tensile stress of reinforcing phase reduce. With the increasing of freezing time, the difference value between the measured residual stress and the primary residual stress of Al matrix and SiC particles both turn out to be greater. Freezing can not destroy the interface combination status between the matrix phase and the reinforcing phase.