Investigations of the Tribological Performance of A390 Alloy Hybrid Aluminum Matrix Composite.

Several challenges stand in the way of the production of metal matrix composites (MMCs) such as higher processing temperatures, particulate mixing, particulate⁻matrix interface bonding issues, and the ability to process into desired geometrical shapes. Although there are many studies showing composites with single particulate reinforcements, studies on composites with multiple reinforcing agents (hybrid composites) are found to be limited. Development of a hybrid particulate composite with optimized mechanical and tribological properties is very significant to suit modern engineering applications. In this study, Al⁻Si hypereutectic alloy (A390) was used as the matrix and silicon carbide (SiC), graphite (Gr), and molybdenum di-sulphide (MoS₂) were used as particulates. Particulate volume (wt %) was varied and sample test castings were made using a squeeze casting process through a stir casting processing route. The evaluation of the mechanical testing indicates that the presence of both the hard phase (SiC) and the soft phase had distinct effect on the properties of the hybrid aluminum matrix composites (HAMCs). Composite samples were characterized to understand the performance and to meet the tribological applications. The 3D profilometry of the fractured surfaces revealed poor ductility and scanning electron microscopy fractography study indicated an intra-granular brittle fracture for HAMCs. Also, the dry sliding wear tests indicated that the newly developed HAMCs had better tribological performance compared to that of A390 alloy.