Development of Hybrid Magnesium-based Composites

In the past decade, magnesium (aluminum) alloy use in the automotive industry has increased in order to reduce vehicle weight and fuel consumption. However, their applications are usually limited to temperatures of up to 120°C. Improvements in the high-temperature mechanical properties of magnesium alloys would greatly expand their industrial applications. As compared to the unreinforced monolithic metal, metal matrix composites have been recognized to possess superior mechanical properties, such as high elastic modulus and strengths as well as enhanced wear resistance. In this study, a novel approach of making hybrid preforms with two or more types reinforcements, i.e., different size particles and fibers, for magnesium-based composites was developed. An advanced and affordable technique of fabricating hybrid magnesium-based composites called the preform-squeeze casting was employed successfully. The microstructures of the hybrid preform and the reinforced magnesium-based composites were analyzed with both optical microscopy (OM), and scanning electron microscopy (SEM). The microstructural analyses show that both the particles and fibers distribute homogeneously in the preform and the composite's matrix material. The engineering performance of the composites was evaluated by tensile testing both the reinforced and unreinforced matrix alloy. The tensile testing results indicate that the tensile properties of the composites are considerably improved compared with those of the matrix magnesium alloy.