Investigation of Effect of Thermal Stresses on Damping and Thermal Expansion Behavior of Al/Al2O3 Metal Matrix Composites

The present investigation is based on the effect of thermal residual stresses on the both thermal expansion and damping behavior of Al/Al2O3 Metal Matrix Composites (MMCs) processed by compo casting. Thermal expansion and damping properties have been studied experimentally as a function of temperature over a temperature range from room temperature to 400 C both in the heating and cooling cycles. Result shows the thermal expansion studies exhibited some residual strain, which increased with the increase in the weight % of the Al2O3. The damping capacity of both the composites and matrix alloy is found to increase with the increase in temperature during the heating cycle, whereas in the cooling cycle damping behavior exhibited maxima which became more pronounced with the increase in the weight percentage of the Al2O3. The damping maximum height decreases if the matrix strength is increased by increasing Al2O3. The appearance of the maxima may be linked with dislocation generation and motion as a result of plastic deformation of the matrix at the Al/Al2O3 interface. This phenomenon is attributed to the thermal stresses generated as a result of coefficient of thermal expansion mismatch between the composite constituent phases.