Evaluation of Microstructure, Mechanical and Tribological Properties of AA6061 Reinforced with SiC and CuO Particles by Friction Stir Processing

Abstract

Friction Stir Processing (FSP) is a great solid-state surface modification method that can be employed to enhance the mechanical and tribological properties of metallic materials by using reinforcement particles. In the present study, AA6061 aluminium alloy plates with 6mm thickness were subjected to FSP process with constant parameters of 1000 rpm rotational speed and 50 mm/min traverse speed, by employing a cylindrical taper pin tool. Silicon carbide (SiC) and copper oxide (CuO) particles were incorporated in various quantities (1 to 4 wt %) to achieve surface metal matrix composites and to evaluate the impact of the reinforcement on the AA6061 alloy mechanical and wear properties. The microstructure investigation, made by optical microscopy method, demonstrated a significant change in grain structure and a uniform distribution of particles in the stir zone. Among four composites samples, the specimen reinforced with 1 wt % SiC and 3 wt % CuO (sample 3) exhibited excellent properties such as tensile strength of 190.7 MPa, elongation of 8.2%, hardness of 72.9 HV, and wear rate of 0.0526 mm³/Nm. The fracture surface analysis, performed by Scanning Electron Microscopy (SEM) technique, revealed reduced number of dimples and absence of visible cracks, as well as improved resistance to fracture and adequate structural integrity. Furthermore, the analysis of the worn surface indicated shallow grooves and minimal debris, confirming diminished abrasive wear. The results achieved by the methods presented above make the optimized FSP-treated AA6061 composite a promising material for industrial applications such as automotive components, aerospace structures, and tooling elements.