Microstructure And Properties Of FeCoCrNi-M_x High Entropy Alloy Coatingsby Laser Cladding

High entropy alloys(HEAs) are defined as solid solution alloys that contain more than five principal elements in equal or near equal atomic percent(at.%). Normally, the atomic fraction of each component is between 5 at.% and 35 at.%. Recently, high-entropy alloys have attracted increasing attentions because of their unique compositions, microstructures, and excellent properties. In this study, Fe Co Cr Ni-Mx(M=V、Mo、Ti、B;x=0, 0.5, 1) high-entropy alloys were prepared on 45# steel by laser cladding. The microstructure and properties of cladding coatings were analyzed by optical microscope, X-ray diffraction, scanning electron microscope, energy dispersive spectrometer, vickers hardness tester and M2000 wear tester.The results showed that the phase of Fe Co Cr Ni-Mx(M=V、Mo、Ti、B;x=0, 0.5, 1) cladding coatings were composed of BCC solid solution and FCC solid solution. The addition of the V, Ti and B elements promoted the formation of the BCC solid solution, respectively. The addition of the Mo element promoted the formation of the FCC solid solution. The σ phase was detected in Fe Co Cr Ni Mo cladding coating. The microstructure of Fe Co Cr Ni-Mx cladding coatings were composed of columnar crystal and equiaxed crystal. With the addition of V, Mo, Ti and B elements, the grains of cladding coatings were refined.The microhardness of the Fe Co Cr Ni-Mx cladding coatings were enhanced because of the solid solution strengthening. From the surface of the coating to the substrate, the microhardness of HAZ was the highest and followed by the cladding layer, both of which were higher than the substrate. With the increasing of V, Mo, Ti and B elements, the microhardness of Fe Co Cr Ni-Mx cladding coatings were improved gradually. Due to the addition of Mo element, the microhardness of the Fe Co Cr Ni Mo coating was improved greatly by the σ phase, which was up to 610.55 HV.Fe Co Cr Ni-Mx alloying coatings presented excellent anti-wear properity. With the addition of V, and B element, wear-resisting resistance of alloying coatings were improved gradually; and the wear types were abrasive wear which wear mechanisms was mainly micro-cutting. The addition of Mo and Ti element improved the wear-resisting properity of coatings. With the increasing of Mo and Ti element, the main wear mechanisms of coatings changed from micro-cutting to fatigue flaking.