Research On Microstructure And Properties Of Ultrasonic-assisted TIG Arc Cladding High-entropy Alloy Coatings

High-entropy alloys(HEA),with excellent wear resistance and corrosion resistance,are ideal coating materials.Tungsten inert gas(TIG)arc cladding HEA coatings has the advantages of high efficiency and high quality,but it also has the problems of coarse grains and element segregation,which deteriorate mechanical and corrosion properties.To tackle the problems,based on the analysis on the preparation method of HEA coatings and the application of ultrasonic in melt treatment,welding,and cladding at home and abroad,to improve the microstructure,mechanical and corrosion properties of TIG arc cladded HEA coatings,this work carried out an experimental study on ultrasonic-assisted TIG arc cladding HEA coatings.The effect of ultrasonic on the phase,microstructure,element distribution,mechanical properties,and corrosion properties was analyzed.The effect of process parameters on the TIG arc cladding AlCoCrFeNi HEA coatings was studied.By changing cladding specific heat input,the process interval of preparing defect-free coatings was obtained.On this basis,the effect of specific heat input on AlCoCrFeNi HEA coatings was studied.It was found that with the increase of specific heat input,the Fe content in the coating increased;microstructure changed from fine equiaxed grains to coarse columnar grains;the microhardness,elastic modulus,and creep resistance increased;corrosion resistance improved.The effect of ultrasonic on TIG arc cladding AlCoCrFeNi HEA coatings was studied.It was found that with the aid of ultrasonic,the phase remained BCC(A2+B2spinodal decomposition)structure;the equiaxed grains became finer,columnar grains disappeared,and the average grain diameter reduced by 70%.more Cr segregated at grain boundaries;the microhardness increased by 20%,elastic modulus and creep resistance increased;the corrosion type changed from intergranular corrosion to uniform corrosion,and the corrosion resistance improved.The effect of ultrasonic on TIG arc cladding Al Co Cu Fe Ni HEA coatings was studied.It was found that with the aid of ultrasonic,the phase fraction of BCC among the microstructure of BCC dendrites and FCC interdendrites increased;secondary dendrite arm spacing reduced by 90%;the dendritic segregation was significantly suppressed;the microhardness increased by 15%,elastic modulus and creep resistance increased;the corrosion type changed from interdendritic preferential corrosion to uniform corrosion,and the corrosion resistance improved.