Wear Performance of TiB2-Reinforced AZ91 Magnesium Metal Matrix Composite Fabricated by Ultrasonic Stir-Casting Process

The tribological performance of a TiB2-reinforced AZ91 magnesium metal matrix composite was investigated for its application in the aerospace and automotive industries. The stir-casting process was used to develop the composite, which was aided by incredibly powerful ultrasonic vibrations. Dry sliding wear tests were conducted using a pin-on-disc tribometer at varying sliding velocities (1-2 m/s) and normal loads (30-50 N). Surface morphology, microstructure, phase analysis, and elemental composition of the fabricated composite were examined using SEM, XRD, and EDX analysis. Owing to the grain refinement and nearly uniform dispersion of the reinforcement particulates, the developed composite showed a considerable enhancement in wear resistance. At all sliding speeds, the wear rate of the composite was found to be increased with an increase in load. In addition, adhesion, oxidation, and delamination were reported as the main responsible wear mechanisms. However, a mechanically mixed layer was seen at high sliding velocity, which acted as a shield against the wear on the composite surface. The developed composite was found to be superior and revealed better wear resistance than the base matrix alloy at all wear test conditions, owing to enhanced hardness and better interfacial capacity of the matrix and the reinforcement.