Study On Cold Spraying Assisted Synthesis Of AlCo_xCrFeNiCu High Entropy Alloy Coating

The use of surface modification technology can greatly increase the strength and hardness of ordinary industrial materials,thereby improving the wear resistance and corrosion resistance of the materials.With high strength,high hardness,good ductility,excellent wear resistance and corrosion resistance,Al Co Cr Fe Ni Cu series high-entropy alloys are widely used in the field about protecting the surface of industrial parts.In order to solve the poor wear resistance and corrosion resistance of ordinary indus trial materials(such as industrial steel),this paper uses cold spray on the 45 steel substrate to assist in the synthesis of AlCo_xCrFeNiCu(x=0,0.5,1,1.5,2)High-entropy alloy coating.The effect of phase and microstructure of cold spray-assisted synthesis about high-entropy alloy coating as well as the effect of structure change on performance are studied by changing the content of Co element,which is of great significance to provide reference and guidance for the cold spray assisted synthesis of hi gh-entropy alloy coatings.The cold spray assisted synthesis technology refers to the preparation of AlCoCrFeNiCu mixed powder prefabricated coatings using low-pressure cold spraying process,and then the induction remelting or laser cladding process is us ed to synthesize AlCo_xCrFeNiCu series high-entropy alloy coatings.In this study,the elemental powders of Al,Co,Cr,Fe,Ni,and Cu were mechanically mixed at 1:x:1:1:1:1(x=0,0.5,1,1.5,2)for 3 hours,then the spraying technology prefabricates mixed pow der coating on 45 steel substrates is prepared through low-pressure cooling,and then the induction remelting and laser cladding technology is used to synthesize AlCo_xCrFeNiCu high-entropy alloy coating.Characterize the microstructure of AlCo_xCrFeNiCu high-entropy alloy coatings with different Co element contents through XRD,SEM,TEM,EDS,etc.;the hardness,wear resistance and corrosion resistance of AlCo_xCrFeNiCu high-entropy alloy coatings with different Co content are tested through hardness microscope(HV-1102),UMT-Tribolab type friction equipment,electrochemical workstation(CHI-660D)and so on.Studies have shown that the AlCo_xCrFeNiCu series high-entropy alloy coatings synthesized by low-pressure cold spray assisted induction remelting are compo sed of a simple FCC+BCC two-phase mixed structure,and different Co element contents promote the increase in the number of dendrites in the Al Co _xCr Fe Ni Cu series high-entropy alloy coatings,and coarsening is obtained obviously.Through surface scan analysis,the microstructure is enriched with Fe,Cr,Co elements in the dendrites,Cu elements are enriched between the dendrites,and Al is evenly distributed in the entire coating;the structure of the AlCo_xCrFeNiCu high-entropy alloy coating assisted cold spraying through induction remelting technology is equiaxed.With the increase of Co content,the hardness first increases and then decreases.When Co=1,the hardness of the alloy coating reaches the maximum of 555.6HV,and the minimum coefficient of friction is 0.361.Coating in 3.5wt.%Na Cl corrosive medium,Al Co _0.5Cr Fe Ni Cu high-entropy alloy coating is more resistant to corrosion,and has a more positive self-corrosion potential(E_corr=–0.37V)and smaller self-corrosion than other Co content coatings current density(I_corr=4.9×10^-6 A·cm^-2).The structure of the AlCo_xCrFeNiCu high-entropy alloy coating synthesized by low-pressure cold spraying assisted laser cladding is a dendritic structure,the main phase of the dendrite is Fe-Cr phase,and the main phase of the precipitated phase between the dendrites is Cu.As the concentration of Co element increases,Cu precipitation between dendrites is promoted.As the proportion of Co element increases,the precipitation of Cu between dendrites is promoted,and the d iffraction peak of the BCC phase in the coating first increases and then decreases,and the diffraction peak of the FCC phase is first weakened and then increased.With the addition of Co element,the Vickers hardness of the coating also increases first an d then decreases.When the content of Co element is 1,the hardness of the high-entropy alloy coating reaches the maximum,with an average hardness of 610.9 HV and a minimum friction coefficient of 0.283.The addition of Co element improves the hardness an d wear resistance of the alloy coating.The wear types of alloys include abrasive wear,abrasive wear and delamination wea.Al Co_0.5Cr Fe Ni Cu high-entropy alloy coating is more resistant to corrosion when it is in 3.5wt.%Na Cl corrosive medium.