Synergetic Effect of Gr-B4C Reinforcement on the Structural and Mechanical Properties of AA6351 Hybrid Metal Matrix Composites

The purpose of this study is to investigate the effects of Graphite (Gr)-Boron Carbide (B4C) reinforcement particles on the mechanical characteristics of an aluminium-based hybrid metal matrix composites. Hybrid metal matrix composites (MMCs) were prepared by adding different proportions of Gr and B4C (0.5–0.5, 1.0–1.0, 1.5–1.5, and 2.0–2.0 wt%) through liquid metallurgy (stir casting) route. The phase, microstructure, EDS, density, hardness, tensile strength of fabricated samples were studied. Through X-ray diffraction analysis, it was established that there was a transitional stage of development between the matrix and reinforcement particles due to interfacial bonding. Furthermore, scanning electron microscopy results indicate a consistent dispersion of reinforcement particles within the aluminium matrix up to the 1 wt% Graphite and 1 wt% B4C. As the proportion of reinforcement increased, a decrease in density was observed, with the lowest density as 2.62 g cc−1 in the sample containing 2 wt% Graphite and 2 wt% B4C. The best mechanical characteristics of the fabricated hybrid metal matrix were observed with 1 wt% Graphite and 1 wt% B4C, with a hardness of 82 HRC, impact strength of 32 Joules, and an engineering ultimate tensile strength of 134.3 MPa.