| High entropy alloys have attracted noticeable attention because of their excellent performances,such as high hardness and strength,excellent wear and corrosion resistance.High entropy alloy is a hot topic in materials world recent years.It can expand the application range of high entropy alloy,which was prepared by laser cladding technology.And coatings save resources and reducing the extra cost significantly.In this paper,Al1.3CrFeNi2CuMox(x=0;0.1;0.3;0.5)and AlCrFeNiMox(x=0;0.2;0.6;1.0)high entropy alloy coatings were prepared by laser cladding technology.The ratio and alloy element with larger atomic radius on the phase consistence,morphology,microstructure and wear resistance were systematically investigated.The results are as follows:The phase of Al1.3CrFeNi2CuMox high entropy alloy coatings are composed of BCC and FCC structures,the samples are characterized by dendrite structure.The dendrite is deduced as BCC phase mainly,which contained Fe,Cr and Mo elements.The interdendrite is deduced as FCC phase mainly,which contained Cu and Ni elements.With the increase of Mo,the forming of BCC solid phase was promoted.At the same time,grain get refinement.A large number of fine equiaxed microstructure could be observed in Al1.3CrFeNi2CuMo0.5 alloy.Because of Mo has large atomic radius,lattice distortion,hardness and wear resistance of the coating increased significantly with the increase of Mo content.The effects of Mo elements on the friction and wear properties of the coatings under different wear parameters were studied by changing the sliding frequency and load parameters.The results showed that the wear volume of the coating decreased at the beginning and then increased along the increase of sliding frequency.When Mo content was less,the wear mechanism was mainly consist of abrasive and adhesion wears.With the increase of Mo content,the wear mechanism changed into abrasive,oxidation and adhesion wears.With the increase of load,the friction coefficient(COF)of Al1.3CrFeNi2CuMox alloy decreased but the volume wear rate increased.With the increase of Mo content,the wear resistance of Al1.3CrFeNi2CuMox high-entropy alloy coating was enhanced significantly.Among them,the wear resistance of Al1.3CrFeNi2CuMo0.5 alloy was the best,and its wear mechanism was composed of abrasive,oxidation and adhesion wears.For AlCrFeNiMox high entropy alloy coating,the phase structure was composed of two kinds of solid solution structure:BCC1 and BCC2,when x=0;0.2.With the increase of Mo content,a small amount of σ phase appeared.The microstructure of the coatings was part of typical dendrite structure.According to the analysis of the composition,the dendrite was mainly BCC1 phase which was rich in Fe,Cr and Mo,and the inter crystalline phase was BCC2 phase which was rich in Al and Ni.With the further increase of Mo content,the grain size was refined,and the formation of phase was promoted.Therefore,the hardness and wear resistance of the coating were increased.The volume wear rate of the coating decreased with the increase of Mo content.The minimum wear rate of the coating was 4.89×10-12m3/N·m.In the initial stage,the wear mechanism of the coating was composed of adhesion and abrasive wears.With the increase of Mo,the wear mechanism changed to abrasive and oxidation wears.With the increase of wear load,the friction coefficient of the alloy decreased first and then increased.At the same time,the wear mechanism was composed of adhesive,abrasive and mild oxidative wears,which was composed of abrasive,oxidative and slight adhesion wears.The volume wear rate of AlCrFeNiMox high entropy alloy coating decreased with the increase of wear load because of the change of wear mechanism. |
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