Microstructural evolution and mechanical characterizations of Al-TiC matrix composites produced via friction stir welding

A study was conducted on the material characterization of aluminium (Al) and titanium carbide (TiC) metal-matrix composites produced via friction stir processing. Different process parameters were employed for the welding process. Rotational speeds of 1600 min^-1 to 2000 min^-1, at an interval of 200 min^-1 and traverse speeds of 100 mm/min to 300 mm/min, at an interval of 100 mm/min were employed for the welding conducted on an Intelligent Stir Welding for Industry and Research (I-STIR) Process Development System (PDS) platform. The characterizations carried out include light microscopy and the scanning electron microscopy analyses combined with Energy-Dispersive Spectroscopy (SEM/EDS) techniques to investigate the particle distribution, microstructural evolution and the chemical analysis of the welded samples. Vickers microhardness tests were used to determine the hardness distribution of the welded zone and tensile testing was conducted to quantify the strength of the welded area compared to the base metal in order to establish the optimal process parameters. Based on the results obtained from the characterization analysis, it was found that the process parameters played a major role in the microstructural evolution. A homogenous distribution of the TiC particles was observed at a high rotational speed of 2000 min^-1 and a low traverse speed of 100 mm/min. The highest hardness value was measured at the stir zone of the weld due to the presence of the TiC reinforcement particles. The tensile strength also increased as the rotational speed increased and 92 % joint efficiency was recorded in a sample produced at 2000 min^-1 and 100 mm/min. The EDS analysis revealed that Al, Ti and C made up the composition formed in the stir zone. The optimum process parameter setting was found to be at 2000 min^-1 and 100 mm/min and can be recommended.