Investigation of Reciprocating Wear Characteristics of Nano-B₄C Reinforced AZ91D Magnesium Metal Matrix Nanocomposites Prepared Through Ultrasonically Assisted Stir Casting Technique

The present study aims to develop a new class of AZ91D magnesium metal matrix nanocomposites reinforced with varying wt.% (0–2%) of B₄C nanoparticles through ultrasonic vibration-assisted stir casting technique and to evaluate the influence of B₄C particles on the microstructure, micro-hardness and wear behaviour of AZ91D nanocomposites. Microstructural characterisation was performed using field emission scanning electron microscope (FESEM) and showed that the B₄C nanoparticles were dispersed uniformly, refinement of grains and well-bonded between the AZ91D matrix and reinforcement particles. XRD patterns of as-cast MMNCs confirmed the presence of α-Mg, β-Mg₁₇Al₁₂, B₄C and MgO phases. Micro-hardness value enhanced by 53.73% with incorporation of 2 wt.% B₄C. The reciprocating wear tests of nanocomposites were examined using ball-on-disc tribotester under applied load of 2 N and observed that wear rate and friction behaviour of AZ91D-2.0B₄C nanocomposites decreased by 48.67 and 28.32%, respectively. FESEM micrographs of worn surfaces indicate that abrasion, oxidation, adhesion and delamination were the main wear mechanisms.