Surface metal matrix composites

This investigation has presented two simple inexpensive processing techniques (direct and indirect) to produce surface metal matrix composites (SMMCs) by the casting route. SMMCs signify that the surface layer of a pre-selected thickness in the product contains the dispersoids, while its core is free from solid inclusion particles. Therefore, an indirect process by which the product can be obtained by using a mechanical setup was especially designed for this purpose. In the indirect process, the product can be obtained by two casting stages. In the present work, an AI-Si alloy was used as the matrix and Sio as the hard phase, which can be impregnated in the surface only. The characteristic equation for both processes is discussed. To check the validity of the obtained equations, several experimental tests were made. The results give a good agreement of both the experimental and the theoretical data. (C) 2001 Published by Elsevier Science Ltd.