الفهرس 
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Abstract
Stir casting method was used to produce conventional metal matrix composites (MMC) with fairly homogenous dispersion of reinforcement material. Commercial pure alurninum and silicon carbide particles (50 urn ) were selected as matrix and reinforcement materials respectively. The matrix was first completely melt and kept constant at 750 °C. Then SiC powder
preheated to 800°C was added during stirring action. No wetting agents were
used. The melt mixture was poured into a metallic mold. The composite contents
were adjusted to contain 5% and 10% volume fractions of SiC. The as-cast
composites were processed by Equal Channel Angular Pressing (ECAP) route
A. The microstructure and mechanical properties were studied.
Results indicated that as-cast AlISiC composites can be successfully
fabricated via a cheap conventional stir casting method, giving fairly dispersed SiC particle distributions and having low porosity levels < 3.6%. After ECAP the mechanical properties have improved compared to as cast composites.
ECAP technique has greatly reduced SiC particles from 50 to Ium after 8 ECAP
passes for AI-IO%SiC. After the first ECAP pass, yield strength has almost
twice its value in the as cast composites. Maximum yield of 245 MPa was
obtained after 8 passes, which is almost four times the corresponding values of the as cast MMC composites. Hardness has also increased to 1.5 times its value in the as cast composites after one ECAP pass. The maximum hardness of 71
HRB obtained after 8 passes, which is almost 3.5 times the corresponding values of the as cast MMC composites.