Microstructure And Properties Of FeCoNiCrTiV_x High Entropy Alloy Prepared By Twin-electrode TIG Cladding

High-entropy alloy possess excellent mechanical properties,outstanding abrasion resistance and good corrosion resistance,which is an important direction for the development and research of new materials.The application technology of high-entropy alloy coating based on high-entropy alloy theory not only inherits the excellent performance of high-entropy alloy,but also reduces the application cost,which has attracted most researcher attention.In this paper,FeCoNiCrTiV high-entropy alloy was investigated,and the cladding coating was prepared on Q235 substrate by twin-electrode TIG welding equipment.The microstructure,micro and macro hardness,friction feature and electro-chemical corrosion resistance of cladding layer were systematically studied.The optimal process parameters were determined as follows:melting current 80 A\80 A,melting speed 80 mm/min,welding arc length 3 mm,argon flow 20 L/min,preset powder bed thickness 2.5 mm.The phase of FeCoNiCrTi0.5V is BCC phase,FCC phase and dispersed TiC particles.With the increase of heat input,the fraction of FCC phase in the cladding layer increases gradually,and B2 ordered BCC solid solution phase appears.The microhardness of the cladding layer decreases with the increase of heat input.XRD results show that the clading layer of FeCoNiCrTiVx(x=0,0.3,0.6,1,x is stoichiometric)high entropy alloy is composed of FCC phase and BCC phase.The intensity of FCC diffraction peaks in V0,V0.6 and V1 clading layers is very low,and almost only BCC phase was formed.The intensity of BCC diffraction peaks increases with the increase of V element content,and the addition of V element reduces the lattice distortion.V0.3 contains more FCC phases.By BSE images and EDS analysis,it is found that the microstructure of the cladding layer is more complex than that of XRD analysis.In addition to BCC and FCC phases,there are Fe2Ti Laves phase and TiC particles.The calculation of jmatpro thermodynamic software also supports this conclusion.FeCoNiCrTiVx(x=0,0.3,0.6,1,X is the stoichiometric number)high entropy alloy coating greatly improves the wear resistance and corrosion resistance of Q235.The microhardness of the cladding layer increases with the increase of V element content except V0.3 clading layer.The highest hardness of V1 clading layer reaches 609.6 HV0.5,which is much higher than that of Q235 substrate.V0.3 clading layer has the lowest hardness due to containing more FCC solid solution phase.The wear test results at room temperature show that the tribological properties of the cladding layer are positively correlated with the microhardness,that is,the higher the microhardness is,the stronger the wear resistance is,and the wear mechanism of the cladding layer is adhesive wear.The results of electrochemical corrosion test showed that the corrosion potential of the substrate,V0,V0.3,V0.6 and V1 were-1.107 V,-0.417 V,-0.137 V,-0.238 V and-0.07 V,respectively.By comparing with the substrate,the corrosion resistance of the clading layer was much better.V element can improve the electrochemical corrosion resistance of cladding layer.The higher corrosion resistance of V0.3 clading can be attributed to more FCC solid solution.