Experimental investigation on the mechanical behavior of Al-7068 hybrid composite with SiC and Si ₃ N ₄ reinforcements

Abstract

This study investigates the tensile strength of hybrid composites developed by reinforcing Al7068 aluminum alloy with silicon carbide (SiC) and silicon nitride (Si ₃ N ₄ ). The Al7068–Si ₃ N ₄ /SiC/SiC/SiC composite was synthesized using the stir casting technique, ensuring a uniform distribution of the reinforcements within the Al7068 matrix by varying the reinforcement levels of micro-sized particles. Silicon carbide (SiC) incorporated at 0 %, 1 %, 0.5 %, 0.5 %, and 1 % by weight, and silicon nitride (Si ₃ N ₄ ) added at 0 %, 1 %, 1.5 %, 2.5 %, and 2 % by weight. The material’s ultimate tensile strength and hardness were measured using a universal testing machine and a Rockwell hardness tester. The presence of Si ₃ N ₄ improved the overall tensile strength of the composite by reducing crack propagation, while SiC contributed to increased hardness and wear resistance. SEM and Optical microscopic investigations revealed significant variations in dendritic structures and reinforcement dispersion across different compositions from S0 to S4. The study aims to assess the impact of combining SiC and Si ₃ N ₄ on the overall mechanical properties of the composite material.