Preparation And Abrasion Properities Of Laser High-entropy Alloying Coatings

High-entropy alloy with multi-principal elements is a novel alloy, which contains five ormore principal elements and each element has an atomic percentage between5%and35%.The invention of high-entropy alloy breaks through the traditional alloy design concept whichbased on single major component, and its microstructure and properties have hugesuperiorities. In this study, CoCrAlNiBx/304and CoCrAlNiTix/304alloying coatings wereprepared on304stainless steel by laser alloying. The microstructure, composition, phasestructure and properties of alloying coatings were analysed by scanning electron microscopy,energy dispersive spectrometer, X-Ray diffraction, vickers microhardness tester,multifunctional material surface performance tester, cavitation erosion tester andelectrochemical tester.Results show that the phase of CoCrAlNi/304alloying coating is composed of simpleBCC solid solution, with the addition of B, Ti elements, the phases of high-entropy alloyingcoatings transform into BCC+FCC solid solution structure. In CoCrAlNiBx/304alloyingcoatings, the addition of B element promotes the formation of fine dendritic crystal, themicrostructure are composed of flat crystal, columnar crystal and dendrite. The microstructureof CoCrAlNiTix/304alloying coatings is composed of flat crystal and isometric crystal, andwith the addition of Ti element, the grains are refined. Moreover, Ti intermetallic compoundemerges from CoCrAlNiTi2/304alloying coating.The strengthening mechanism of laser high-entropy alloying coatings is solid solutionstrengthening, and with the addition of B, Ti element, the microhardness of coatings isenhanced. Particularly, the average microhardness of CoCrAlNiTix/304alloy system reachesto690HV. CoCrAlNiBx/304and CoCrAlNiTix/304alloying coatings present excellentwear-resisting properity. With the increasing of B element, abrasion resistance ofCoCrAlNiBx/304alloying coatings is improved gradually; In CoCrAlNiTix/304alloyingcoatings, CoCrAlNiTi0.5/304, CoCrAlNiTi2/304alloying coatings possess the optimumwear-resisting properity.The studies of cavitation erosion and electrochemical corrosion properties in3.5%NaClsolution show that CoCrAlNiBx/304and CoCrAlNiTix/304alloying coatings present excellent cavitation erosion resistance, the surface roughness after cavitation erosion is1/10than304stainless steel. Among these alloy systems, CoCrAlNiTix/304high-entropy alloying coatingshave the best cavitation erosion resistance. The electrochemical corrosion resistance ofCoCrAlNiBx/304and CoCrAlNiTix/304alloying coatings is superior to304stainless steel, andmost alloying coatings contain passive region, CoCrAlNi/304, CoCrAlNiB0.1/304,CoCrAlNiB0.2/304and CoCrAlNiTi1/304high-entropy alloying coatings possess the optimumelectrochemical corrosion resistance.