Effect of matrix/reinforcement particle size ratio (PSR) on the mechanical properties of extruded Al-SiC composites

This paper studied the combined effects of matrix-to-reinforcement particle size ratio (PSR) and SiC volume fraction on the mechanical properties of extruded Al-SiC composites. A powder metallurgy technique (PM) of cold pressing at 500 MPa followed by hot extrusion at 580 degrees C was adopted to produce Al/SiC composite. Aluminum powder of size 60 m and silicon carbide with different sizes, i.e., 50, 20, and 8 m, were used. Three different volume fractions of SiC were employed, i.e., 5, 10, and 15%, for each investigated size using a constant extrusion ratio of 14.36. The effect of matrix-to-reinforcement PSR on the reinforcement spatial distribution, fabricability, and resulting mechanical properties of a PM-processed Al/SiC composite were investigated. It has been shown that small ratio between matrix to reinforcement particle size resulted in more uniform distribution of the SiC particles in the matrix. As the PSR increases, the agglomerations and voids increase and the reinforcement particulates seem to have nonuniform distribution. In addition, the agglomerations increased as the volume fraction of the SiC increased. It has also been shown that homogenous distribution of the SiC particles resulted in higher yield strength, ultimate tensile strength, and elongation. Yield strength and ultimate tensile strength of the composite reinforced by PSR (1.2) are higher than those of composite reinforced by PSR (7.5), while the elongation shows opposite trend with yield strength and ultimate tensile strength.