Existence of Good Bonding between Coated B4C Reinforcement and Al Matrix via Semisolid Techniques: Enhancement of Wear Resistance and Mechanical Properties

An Al 6061 alloy matrix reinforced with the coated B₄C particles was used for the present study. The cohesion of the reinforcing ceramic particles is poor at temperatures near the melting point of aluminum and leads to inferior mechanical and tribological properties of developed aluminum matrix composites with nonuniform distribution of the reinforcement. The main reason for coating the particles is to improve the bond between the reinforcement and molten alloy and thus to eliminate interfacial reactions. The great enhancement in strength values of the composites in this study can be ascribed to the effective load-bearing capacity of disintegrated B₄C particles that are adherently bonded to the matrix alloy. Homogeneity and reduction in the particle size of B₄C during the extrusion process is evidenced in the microstructural studies.