Formation mechanism and properties of FeCoCrNiAlx high-entropy alloy coatings by electrical explosion spraying

Abstract

FeCoCrNiAlx (x=0, 0.5, 1.0, mole ratio, the same below) coatings were prepared on the surface of TC4 titanium alloy by electric explosion spraying technology. The effects of Al content on the phase structure, surface morphology, microhardness and wear resistance of high-entropy alloy coatings were studied by means of XRD, SEM, EDS, microhardness tester and friction and wear test. The results show that the grain size of the coatings is nano-scale, and simple FCC, BCC and FCC+BCC solid solutions are formed. With the increase of Al element, the phase structure is gradually changed from FCC phase to BCC phase. The surface of the coatings is smooth and dense, without obvious cracks, and the elements are evenly distributed on the surface of the coatings, and no obvious segregation of elements is found. The scratch test shows that the average critical load for the failure of the FeCoCrNiAl1.0 coatings is 37.2 N. The coating is metallurgically bonded to the substrate. The hardness and wear resistance of the coatings are positively correlated with the Al content. When x is 1.0, the average microhardness reaches the maximum value of 531.8HV, which is about 1.62 times that of the substrate. The FeCoCrNiAl1.0 coatings have the smallest amount of wear, and the wear resistance is about 3.9 times that of the substrate. The wear mechanism is mainly abrasive wear.

Keywords

• electrical explosion spraying
• high entropy-alloy coating
• alloying
• wear resistance