Research On Laser High Entropy Alloying On The Surface Of Single-element Ni Base Alloy

There are at least5principal elements in the multi-principal element high entropy alloys,with atom fraction of each elements between5%-35%. High entropy alloys have manyexcellent properties, while high hardness，excellent wear resistance. High temperatureresistance and anti-oxidation performances are the most outstanding properties. High entropyalloys are still in the research stage, not widely used. In the experiments, FeCoCrAl/Ni andFeCoCrAlCuVx/Ni (x=0,0.2,0.5,0.8,1) laser high-entropy alloying layers were successfullyprepared by laser surface alloying on Ni201. Microstructure, constituent structure, hightemperature oxidation resistance and friction-and-wear properties were investigated using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy spectrum analyzer(EDS), friction and wear testing machine.Experimental results showed that the phase composition of FeCoCrAl/Ni andFeCoCrAlCuVx/Ni laser high entropy alloy layers exhibited simple solid solutions. TheFeCoCrAlCu/Ni and FeCoCrAlCuV0.2/Ni high entropy alloy exhibited a single FCC structure.The phase composition of FeCoCrAl/Ni and FeCoCrAlCuVx/Ni (x=0.5,0.8,1) laser highentropy alloy layer was FCC+BCC phases. Meanwhile, with the increase of V content,thelattice constant of FeCoCrAlCuVx/Ni series laser high entropy alloying layers increased andthe lattice distortion of FeCoCrAlCuVx/Ni series laser high entropy alloy layers also increased.FeCoCrAl/Ni and FeCoCrAlCuVx/Ni laser high entropy alloy layers were mainly composed ofthe dendrite, columnar and equiaxial crystal. The segregation of Al appeared inFeCoCrAlCuVx/Ni laser with high entropy alloy layer, Al mainly was enriched in dendrites,the Co, Cr, V, Fe, Cu, Ni were uniformly distributed in the coating. The hardness of theFeCoCrAl/Ni high entropy alloy was the hardest, it can reach698HV, The hardness ofFeCoCrAlCuVx/Ni series laser high entropy alloy layers was335-668HV. With the increase ofV, the hardness increased gradually. The hardness of the FeCoCrAlCuV/Ni high entropy alloywas the hardest, it can reach668HV, about6times that of the substrate.FeCoCrAl/Ni and FeCoCrAlCuV/Ni laser high entropy alloy layer has excellent hightemperature oxidation resistance at900℃. The oxide of the FeCoCrAl/Ni laser with highentropy alloy layer mainly included Cr2O3and Al2O3. The oxide of the FeCoCrAlCuV/Ni laser high entropy alloy layer mainly included Cr2O3, Al2O3and CuO,and Cr2O3and Al2O3are inthe external oxidation layer, CuO is in the internal oxidation layer. The substrate and laser highentropy alloy layer abrasion resistance from low to high order: Ni201<FeCoCrAlCu/Ni<FeCo--CrAl/Ni<FeCoCrAlCuV/Ni. FeCoCrAlCuV/Ni laser high entropy alloy layer has good wearresistance, which was4.57times that of the substrate.