Collected studies on interfaces and interphases as related to the behaviour of fibre-reinforced aluminium alloy composites

This paper is an essentially practical treatment of interphases and interfaces and of their influence on the properties of a number of metal matrix composites (MMCs). The illustrations are drawn from the authors' experiences and have been chosen to underline the importance of detailed microstructural analysis for elucidating the fabrication behaviour and the mechanical performance of this group of materials. The work involves a series of MMCs based upon different combinations of aluminium alloy and ceramic/carbon fibre (both continuous and short) and made using the method of low-pressure liquid metal infiltration (LMI). Detailed analyses of the composite microstructures are given. with particular attention being paid to the interface regions. The data are used to categorize an interface according to the type of bond, that is a mechanical bond resulting from thermal mismatch between the fibre and metal matrix, or a chemical bond, with or without second phase, caused by chemical reaction. The information is then employed to account for aspects of composite fabrication, such as the cast microstructure produced by the LMI method and the effect of heat treatment, and to elucidate composite properties such as stiffness, yield stress and failure strength.