Damping Mechanism of SiC Particle Reinforced Al Matrix Composites

The low-frequency internal friction behavior of SiC particle reinforced Al matrix composites was studied over a temperature range from 23°C to 550°C at frequencies of 0.1, 1 and 5 Hz. The experimental data were analyzed in terms of the K-G-L dislocation theory and the anelastic relaxation of grain boundary sliding. Two internal friction peaks of the composites were respectively observed over the temperature ranges of 100~250°C and 200~500°C. The dislocation motion is the important damping mechanism of the composites at low temperatures, while the grain boundary relaxation plays a dominant role at high temperatures. The activation energies for dislocation relaxation and grain boundary sliding are 1.2 eV and 1.57 eV, respectively.