Research on the Preparation of High-Entropy Alloy Particle Reinforced Az31 Magnesium Alloy Composites by Plasma Spraying Combined with Friction Stir Processing Technology

Abstract

The inherent imbalance between mechanical strength and ductility has long limited the widespread use of particle-reinforced magnesium matrix composites (MMCs). In this work, AZ31-based composites reinforced with high-entropy alloy (HEA) particles showed simultaneous increases in tensile strength, elongation capacity, and wear resistance. This study presents a unique fabrication method that combines plasma spraying and friction stir processing (FSP) to create AlCoCrFeNi HEA particle-reinforced surface layers on AZ31 magnesium alloys. Microstructural studies have shown that the use of both FSP and HEA reinforcements significantly reduces the grain size of the magnesium matrix. The reinforcements were found to be uniformly distributed and metallurgically bonded to the matrix, with a diffusion interface zone thickness of approximately 500 nm. Compared with the untreated alloy, the modified composite demonstrated notable mechanical improvements: hardness increased by 49.9 HV, YS rose by 92 MPa, and ultimate tensile strength improved by 43 MPa. Additionally, ductility exhibited a 4.5% gain relative to the base material. Among the various mechanisms responsible for strengthening, grain refinement played a dominant role, accounting for approximately 48.9% of the increase in YS. Tribological evaluation further showed a marked enhancement in wear resistance, as the average friction coefficient dropped from 0.305 in the base material (BM) to 0.216 in the composite. The dominant wear mode transitioned from adhesive to abrasive wear following HEA reinforcement.

Keywords: Plasma spraying, Friction stir processing, High-entropy alloy, Magnesium matrix surface composite, Mechanical properties, Wear