Tailoring microstructure and enhancing tribological performance through aluminum content in AlNbTiVZr high-entropy alloys

This study systematically investigates the influence of aluminum content (5, 10, 15, and 20, in at.%) on the microstructure, mechanical properties, and wear behavior of equiatomic AlNbTiVZr highentropy alloy. The alloys were characterized using X-ray diffraction, scanning electron microscopy, energydispersive spectroscopy, microhardness testing, and reciprocating sliding wear tests. The results show that all alloys consist of a BCC matrix and a C14 Laves phase. With increasing Al content, the Laves phase morphology evolves from needle-like to a continuous cellular network. Microhardness increases monotonically from 371.7 HV to 528.9 HV due to solid solution strengthening, second phase strengthening, and grain boundary pinning. The average friction coefficient increases with Al content, whereas the wear rate decreases by nearly an order of magnitude. A wear mechanism transition from adhesive-dominated wear to oxidative-abrasive wear is observed with increasing Al content. These findings demonstrate that Al content effectively tailors the microstructure and enhances the tribological performance of AlNbTiVZr alloys, providing guidance for designing high-entropy alloys.