Preparation of AlCoCrFeNi/W-TiC HEA composite coating by laser cladding

Abstract

In this paper, AlCoCrFeNiW2-x(TiC)x high-entropy alloy coatings (HEA) (x: mass fraction, x = 0, 0.5, 1.0, 1.5, and 2) were prepared on 316 stainless steel (316 L SS) substrate by laser cladding technique. The microstructure, phase, microhardness, wear resistance and corrosion resistance of the HEA composite coatings were discussed by adding different mass fractions of W and TiC particles. The results show that the coatings are metallurgically bonded under the experimental parameters, and the grain size of the coating decreases from the interface to the surface, which is in accordance with the constitutional undercooling criterion. Meanwhile, the contents of W and TiC can adjust the mechanical properties of the coatings. The microhardness of the coatings increases and then decreases with the variation of x value, which can be explained by the large number of TiC particles leading to severe lattice distortions and high internal stresses, which results in the fluctuation of microhardness in the cross-section. The coating exhibits the best microhardness, with an average microhardness of 452 HV when x = 0.5. The wear resistance of the coating is better with an average coefficient of friction of 0.4474 when x = 0.5. However, due to the presence of phase-boundary defects in the composite coatings, which contain cationic and anionic vacancies, When the passivation film is damaged by Cl-, the electrolyte will penetrate along the phase boundary defects and generate corrosive microcells.