Microstructure and elevated temperature wear behavior of laser-cladded AlCrFeMnNi high-entropy alloy coating

Abstract

The AlCrFeMnNi high-entropy alloy (HEA) coatings were deposited on 316L stainless steel through laser cladding technology that employs pre-alloyed HEA powders. The microstructure, phase composition and hardness of the laser-cladded coatings prepared at different laser scanning speeds were investigated. The wear behavior and properties of the HEA coatings at different temperatures (from room temperature to 600 °C) was comprehensively evaluated using a pin-on-disc test. It was demonstrated that the laser-cladded AlCrFeMnNi HEA coatings exhibited dense and uniform microstructures consisting of a single BCC solid solution phase. A columnar-to-equiaxed transition structure feature was observed in the molten pool of the laser-cladded coating. The coatings possessed better high-temperature wear performance due to the protective effect of oxide films on the wear track. The coating at 400 °C exhibited the best wear resistance, which had the lowest friction coefficient and wear rate of 0.48 and 1.246 × 10−4 mm3/N · m, respectively. At room temperature, the main wear mechanism of the coating was abrasive wear. However, the predominant wear mechanism at high temperatures was oxidation and adhesive wear.