Modelling and Numerical Computation of Thermal Expansion of Aluminium Matrix Composite with Densely Packed SiC Particles

The coefficient of thermal expansion (CTE) is one of the most important physical properties of metal matrix composites (MMCs). The thermal expansion response is correlated to the microstructure, the deformation of the matrix, and the internal stress conditions. In the present study the physical CTE of aluminium matrix composite (AMC) reinforced with 70 vol. % SiC particles is analytically computed in order to explain abnormalities in the thermal expansion behaviour obtained experimentally. The numerical modelling was carried out from 20C to 500C using finite element analysis (FEA) based on two-dimensional unit cell models. These unit cell models are created with particular attention on the effects of microscopic voids and phase connectivity obtained from geometrical factors such as the phase shape and particle distribution. The used unit cell models consider the composites as a continuous rigid phase infiltrated with the ductile Al matrix. The obtained thermal expansion behaviour is strongly influenced by the presence of voids. A comparison of physical CTE with the experimental results shows a good agreement.