Microstructure and wear characteristics of hybrid reinforced (ex-situ SiC-in-situ Mg2Si) Al matrix composites produced by vacuum infiltration method

Abstract

Hybrid composite materials combine the advantages of two or more reinforcement materials and may contain unique physical, mechanical and tribological properties that cannot be achieved with any other materials. In this study; A356, A380, and A413 alloys were chosen as matrix materials. Prepared SiC preforms were employed as ex-situ reinforcing material, and AM50 magnesium alloy with 5%, 10% and 15% weight ratios were added to the liquid metal to produce hybrid composites via the vacuum infiltration process. The effects of the amount of added AM50 alloy on the microstructural and mechanical properties were investigated. The formation of primary Mg2Si, eutectic Mg2Si, Si eutectic, SiC particles and & alpha;-Al grains were observed in the microstructure. As the weight ratio of the added AM50 alloy increased, the hardness and wear resistance of the composite samples did not significantly improve. However, the wettability of the liquid aluminum to the SiC particles seemed to be improved by the addition of AM50 alloy, especially for A380 and A413 alloys. However, excessive Mg ratio increased the viscosity of the alloy in the liquid state and caused insufficient infiltration in the castings, especially for A413 alloy. The differentiations in the hardness and wear properties depending on the processing parameters are discussed in the paper.