Optimizing Al6061-Based Hybrid Metal Matrix Composites: Unveiling Microstructural Transformations and Enhancing Mechanical Properties Through Ni and Cr Reinforcements

Abstract

This study investigates the development of Al6061-based Hybrid Metal Matrix Composites (HMMCs) reinforced with nickel (Ni) and chromium (Cr) to enhance their mechanical properties. Employing the stir casting method, the research aimed to achieve a homogeneous distribution of Ni and Cr particles, varying from 1 to 3 wt.%, in the Al6061 matrix. Additional elements like graphite (up to 3 wt.%) and magnesium (1 wt.%) were incorporated to improve selflubrication and wettability. The fabrication process involved precise temperature control at 750°C and automatic stirring to ensure even dispersion of the reinforcing particles. The composites were then molded, solidified, and prepared for mechanical testing. SEM-EDS analysis was utilized to analyze the elements' distribution and the composites' microstructural integrity. Mechanical tests, including tensile, flexural, and hardness tests, followed ASTM standards. Significant findings revealed that the specimen with two wt.% Ni and two wt.% Cr (designated as SM2) demonstrated the most balanced improvement in mechanical properties: a tensile strength of 236.08 MPa, a flexural strength of 417.70 MPa, and a hardness of 127.00 HRB. However, an increase in Ni and Cr content beyond 4 wt.% led to non-homogeneous dispersion, manifesting as cracks, voids, and agglomeration, negatively impacting ductility and elongation properties. The study's unique contribution lies in its detailed examination of the effects of varying Ni and Cr concentrations on the mechanical properties of Al6061-based composites, providing valuable insights for material optimization in highperformance applications. This research underscores the delicate balance required in composite material design, particularly in enhancing specific mechanical properties without compromising overall material integrity. It provides crucial insights into the role of Ni and Cr reinforcements in Al6061 composites, highlighting their potential for engineering applications that demand high strength, flexibility, and hardness.