Preparation And Microstructure And Properties Of MoNbTaTiV Refractory High Entropy Allo

Refractory high-entropy alloys are a new type of multi-component material.Research on refractory high-entropy alloys will help promote the development of new materials,pro vide more possibilities for the application of high-performance materials,and help explore new alloy designs.concept to meet the needs of various special applications.Therefore,thi s study used laser cladding technology to prepare a refractory high-entropy alloy coating w ith excellent mechanical properties,wear resistance and corrosion resistance on the surface of Q235 steel.The microstructure and properties of the coating were analyzed and studied by means of X-ray diffractometer（XRD）,scanning electron microscope（SEM）,microhard ness tester,friction and wear testing machine and electrochemical workstation.According to the selection principle of refractory elements in refractory high-entropy alloys,Mo,Nb,Ta,Ti,and V were selected as the constituent elements of refractory high-e ntropy alloys,and the phase structure of the alloys was analyzed by empirical parameters a nd phase diagram calculations.In order to predict,the MoNbTaTiV refractory high-entropy alloy coating was prepared by laser cladding technology.The process parameters of refract ory high-entropy alloy coating prepared by laser cladding were optimized,and the influenc e of these parameters on the coating quality was discussed.Finally,the microstructure,mec hanical properties,wear resistance and corrosion resistance of the refractory high-entropy a lloy coating prepared under the optimal process parameters were studied.The main conclus ions are as follows:（1）The optimal process parameters for preparing MoNbTaTiV refractory high-entrop y alloy coatings by laser cladding are:laser power P=3000W,scanning speed V=5mm/s,po wder feeding rate Vf=15g/min.The surface morphology of the coating prepared under thes e process parameters is smooth without particles,and the cross-section has no defects such as cracks and holes,forming a good metallurgical bond with the substrate.（2）The research shows that the laser cladding MoNbTaTiV refractory high-entropy all oy coating is composed of BCC solid solution phase and a small amount of intermetallic co mpound Fe₂Ti,which is consistent with the theoretical calculation results.The microstruct ure at the top of the coating is fine equiaxed crystals,and the bottom and middle of the coat ing are mainly composed of columnar dendrites.（3）The average hardness of the coating reaches 756.7HV_0.2,which is 4 times that of th e substrate hardness of 189 HV_0.2.The wear amount of the substrate Q235 steel in 20 minu tes is 3.6 mg,which is 2.77 times of the wear amount of the refractory high-entropy alloy c oating（1.3 mg）.The MoNbTaTiV refractory high-entropy alloy coating has a larger capacit ive arc radius,higher self-corrosion potential and an order of magnitude lower self-corrosi on current density than the substrate in 3.5%NaCl solution,showing good corrosion resist ance.