Microstructure Characterization and Thermal Expansion Behaviour of Interpenetrating Alumina/Aluminium Composites

Abstract

Interpenetrating phase composites (IPCs) are a new class of composite materials in which at least two of the constituent phases are three-dimensionally continuous. Such interconnected microstructures suggest improved combination of properties and increased damage tolerance. However, identifying those microstructures has been a difficult task. Interpenetrating phase Alumina/Aluminium composites were fabricated by a displacement reaction between solid silica glass rods and molten aluminium. The composite microstructures were characterized in terms of grain size and contiguity to evaluate the distribution and connectivity of the Al203 and Al phases. The thermal expansion response of these composites was studied. Coefficients of thermal expansion (CTEs) were observed to vary significantly with temperature and displayed non-linear behaviour. It is thought that this indicates an influence of the interconnectivity of the metal phase mainly. Comparisons are made with well-known methods for predicting CTEs of ceramic/metal composites.