Mechanical Properties of Aluminum–4043/Nickelcoated Silicon Carbide Composites Produced via Stir Casting

Abstract

Aluminum metal matrix composites (Al-MMCs) have become attractive for engineering structural applications due to their excellent properties and are increasingly seen as alternative to the conventional monolithic materials particularly in the automotive, aerospace and defence industries. In this study, Al-4043/Ni-coated SiC composite was developed via stir casting process and the mechanical properties of the composites investigated. The composites were produced with varying SiC reinforcement fraction between 5-25 wt%. The microstructure of the composites was characterized using optical microscope and tensile properties of the composite with the monolithic Al-4043 alloy were assessed using a universal testing machine. The composite hardness was assessed using a Brinell hardness testing machine, energy required to break the composite was assessed using Charpy impact testing machine and the wear rate of the composites were evaluated using a Rubin Disc machine. The composites were characterized to possess Al-SiC eutectic microstructure with SiC solid solution precipitates and SiC particles uniformly distributed in the Al matrix. The density of the composites was found to linearly increase with increasing SiC reinforcement fractions. The tensile strength, yield strength and elastic modulus were found to increase with increasing SiC reinforcement fraction and highest values obtained for composite with 25 wt% SiC were 350 MPa, 254 MPa and 13.4 GPa respectively. However, the elongation of the composite with the highest reinforcement was lowest at a value of 10%. The hardness, compressive strength and impact energy of the composites increased significantly as composite with 25 wt% SiC possessed 76 HB, 184 MPa and 48 J respectively. The wear resistance of the Al-4043/SiC composites with highest SiC reinforcement was found to be eleven times that of the monolithic Al-4043 alloy.