Research On Wear And Corrosion Resistant High-entropy Alloy Coatings Of Laser Cladding

To prolong the service life of the blade,a series of high-entropy-alloy(HEA)composition is designed based on the cluster-plus-glue-atom model.And the wear and corrosion HEA coating was fabricated on 904L stainless steel by laser cladding.Firstly,the effects of cluster-plus-glue-atom model and the parameters of laser cladding on the structure and performance of HEA coatings were studied,the interaction law between the parameters and structure of coating were revealed,and the controllable preparation of coating were realized;Secondly,under the best process parameters,the influence of Al element and Cr element content on the microstructure and performance of the coating were studied;Finally,the effect of the ratio of Al element and Ti element on the microstructure and properties of Al_xTi_1-x(FeCoNi)₁₂Cr₃(x=0,0.25,0.5,0.75)coating was studied.XRD,SEM,EDS,EBSD,TEM were used to analyze the phase structure,microstructure,composition,grain size distribution,and microstructure of the coating.The properties of the coating were tested by microhardness tester,high-speed reciprocating friction and wear machine and electrochemical workstation.The main conclusions are as follows:(1)The phase of the coatings mainly consists of FCC and ordered B2 phase.With the increase of laser output power,the microhardness of the coating has increased because of the precipitation of ordered phases.At the same time,the wear resistance of the coating is also improved.The wear mechanism of the coating is abrasive wear and adhesive wear.When the laser output power is the lowest,the coating exhibits excellent corrosion resistance.(2)A series of[Al-(FeCoNi)₁₂]Al_xCr_3-x(x=0,0.5,1,1.5)HEA coatings with high wear and corrosion resistance have been designed based on the cluster-plus-glue-atom model,and successfully fabricated by laser cladding on 904L stainless steel.When x=0 to x=1.5,the microstructure of the coating is transformed from columnar into cellular dendrite.The phase of the coatings mainly consists of FCC and BCC.The microhardness of the coatings reaches the highest value of 580 HV_0.2 in Al_2.5Cr_1.5coating.And the wear resistance of Al_2.5Cr_1.5 coating becomes best.The Al_2.5Cr_1.5coating exhibits the highest self-corrosion potential and lowest self-corrosion current density.(3)The phase of the Al_xTi_1-x(FeCoNi)₁₂Cr₃ coating is composed of single FCC phase,no carbides and brittle phases of Ni₃Ti and Fe₂Ti Laves is produced.The microstructure of the coating is mainly composed of columnar crystals.With the change of Al,Ti,the microstructure of the coating is transformed from columnar into irregular cellular dendrite and a small amount of dendrites.The average microhardness of the coating is about twice that of the substrate,and the wear resistance of the coating is also improved.