Synthesis And Design Of Multi-principal Elements High-entropy Alloy Coating On Fe Alloy

High-entropy alloys with multi-principal elements are a kind of new alloys withover five principal elements and each element has an atomic percentage no more than35%, which break through the concept of traditional alloy design based on one or twometal elements.The FexCoCrAlCu high-entropy alloys, Fe0CoCrAlCu+x%TiC and FeCoCrAlCu+x%TiC high entropy alloy matrix composite coatings were synthesized on Q235steelby laser cladding. The coatings’ microstructure, chemical composition, microhardness,and tribological properities were investigated by light optical microscopy (LOM), X-Raydiffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer(EDS), Vickers microhardness and Friction and wear tester.Analysis showed that the phase of FexCoCrAlCu high-entropy alloys in this studyare simple BCC solid solution structure in the FexCoCrAlCu system. With the increase ofscanning rate, the microstructure become more and more thin. The cladding may bedivided into bright layer, transitional layer, heat-affected zone and the substrateorganization. The cladding thickness may reach800μm. the microstructure is mainlycomposed of dendrite, columnar and equiaxed grains, and the segregation of Cu isobserved due to the different enthalpy among the five elements. After laser cladding, theaverage hardness of high-entropy alloys coating reaches700-1000HV. Meanwhile, withthe increase of Fe component, the microhardness of FexCoCrAlCu system high-entropyalloys decreases gradually. From the subsurface to interface, the mixing entropy isrespectively1.61R,1.61R,1.49R,0.873R,0.300R,0.299R, which realizes the changefrom the low entropy, medium entropy to high entropy on Q235steel surface. Results show that the high-entropy alloy coatings with different TiC content are allcomposed of body-centered (BCC) solid solution phases. During the process of lasercladding, the addition of TiC does not cause the formation of complex carbide phases.The microstructure of coatings with different TiC content is typical dendrite. Elementsegregation between the dendrite and interdendrite can be effective inhibited by lasercladding with rapid solidification. The increase of TiC content leads to grain refinementand the increasing of microhardness. After the Laser Cladding, the hardness of thesample was obviously improved. Among them the FeCoCrAlCu high-entropy alloyscoating’ average hardness is over958HV. The increase of TiC content lead to grainrefinement and the increasing of microhardness. When the TiC content come up to50%,the average hardness of FeCoCrAlCu high-entropy alloys coating is1100HV.FexCoCrAlCu high entropy alloy coating and FeCoCrAlCu+x%TiC high entropyalloy matrix composite coating all show good resistance to friction and wear properties.The wear mechanisms are mainly abrasive wear, adhesive wear and the shelling of hardphase. The abrasion resistance of FexCoCrAlCu high entropy alloy coatings graduallyreduces with the increasing of Fe content. With the increasing of the TiC content, thewear resistance of FeCoCrAlCu+x%TiC high entropy alloy matrix composite coatingincreases gradually.