In-situ TiC reinforced CoCrCuFeNiSi0.2 high-entropy alloy coatings designed for enhanced wear performance by laser cladding

Abstract

In-situ synthesis of TiC reinforced CoCrCuFeNiSi0.2 high-entropy alloy (HEA) coatings were fabricated on the surface of 304 stainless steels by laser cladding. The influence of Ti and C addition on the phase composition and microstructure of the CoCrCuFeNiSi0.2 HEA composite coatings reinforced by (Ti, C)x (x = 0, 0.5, 1.0, 1.5) were investigated by X-ray diffractometer, optical microscope and scanning electron microscope, respectively. The hardness and the room-temperature wear resistance of the HEA coatings were measured by Vickers hardness tester and dry sliding friction and wear tester. The experimental results show that the coatings without Ti and C consist of a single FCC solid solution structure. By the addition of Ti and C, the coatings consist of FCC solid solution and TiC. The microstructure of the HEA coatings are composed of typical dendrites. With the addition of Ti and C, the in-situ TiC ceramics are mainly distributed at the grain boundaries. Moreover, by further increase of the (Ti, C)x content, the volume fraction of the TiC ceramic in the composite coating is also gradually increased. The microhardness and wear resistance of the coatings with Ti and C additions are significantly improved, compared to those of the coatings without any such addition. Particularly, for the (Ti, C)1.0 coating, its average microhardness and wear volume is 498.5 HV0.2 and 0.42 mm3, respectively. In addition, the addition of Ti and C gradually reduce the coefficient of friction of the CoCrCuFeNiSi0.2 (Ti, C)x HEA coatings.