The behaviour of aluminium matrix composites under thermal stresses-a review

Abstract

The present review work elaborates the behaviour of aluminium matrix composites (AMCs) under various kinds of thermal stresses. AMCs find a number of applications such as automobile brake systems, cryostats, microprocessor lids, space structures, rocket turbine housing and fan exit guide vanes in gas turbine engines. These applications require operation at varying temperature conditions ranging from high to cryogenic temperatures. The main objective of the paper is to understand the behaviour of AMCs during thermal cycling, under induced thermal stresses and thermal fatigue. It also focuses on the various thermal properties of AMCs such as thermal conductivity and coefficient of thermal expansion (CTE). CTE mismatch between the reinforcement phase and the aluminium matrix results in the generation of residual thermal stress by virtue of fabrication. These thermal stresses increases with increasing volume fraction of the reinforcement and decreases with increase in interparticle spacing. Thermal cycling enhances plasticity at the interface resulting in deformation at stresses much lower than their yield stress. Low and stable coefficient of thermal expansion can be achieved by increasing the volume fraction of the reinforcement. The thermal fatigue resistance of AMC can be increased by increasing the reinforcement volume fraction and decreasing the particle size. The thermal conductivity of AMCs decreases with increase in reinforcement volume fraction and porosity.