Internal friction behavior in SiC particulate reinforced aluminum metal matrix composite in thermal cycling

A SiC particulate reinforced 1040 commercially pure aluminum was thermally cycled in air between 20 and 300 °C up to 500 cycles. The damping capacities of the samples after 50 and 500 cycles were measured against temperature and strain amplitude. Thermal cycling causes the increase in dislocation density, which leads to the increases in damping capacity. A damping peak observed at the range of 150–200 °C is linked to the thermal stresses caused by the difference of the thermal expansion coefficients of the matrix and the reinforcement. Thermal stresses are relaxed by dislocation motion. Peak temperature goes up due to thermal cycling. The activation energy of the internal friction peak was calculated by Arrhenius equation, yielding 1.02 eV and 1.09 eV for 50 and 500 cycles, respectively. Increase in dislocation during thermal cycling is responsible for the increase in peak temperature and activation energy.