Fabrication and Mechanical Characterization of Al 7075 Hybrid Metal Matrix Composite Reinforced with B4C and Coconut Shell Fly Ash via Powder Metallurgy

Abstract

This study presents the fabrication and mechanical property evaluation of hybrid aluminum matrix composites (HAMC) using aluminum 7075 (Al7075) alloy reinforced with boron carbide (B4C) and coconut shell fly ash (CSFA). Al7075, widely used in aerospace applications due to its high strength-to-weight ratio, superior hardness, and excellent wear and corrosion resistance, requires further property enhancement to broaden its applicability. The HAMCs were fabricated via the powder metallurgy method, incorporating varying weight percentages of B4C (0%, 3%, 6%, 9%, and 12%) and a fixed 3% CSFA. Mechanical property analysis revealed that hardness increased by 33% with 12% B4C and 3% CSFA reinforcements. Tensile strength improved by 66% with 9% B4C and 3% CSFA but decreased with further reinforcement addition. Elongation showed a decline as reinforcement content increased. Impact energy peaked at 2.3 J with 9% B4C and 3% CSFA, reducing with higher reinforcement levels. Optical micrographs confirmed the homogeneous distribution of B4C and CSFA particles in the Al7075 matrix, contributing significantly to the enhancement of hardness, tensile strength, and impact strength. This study demonstrates the potential of hybrid reinforcements in improving the mechanical properties of Al7075 composites for advanced applications.