| As a new type of material,high-entropy alloy had the advantages of high strength,high hardness,excellent wear resistance,corrosion resistance,and high thermal resistance.It was an alloy material with good application prospects.In this thesis,the FeCoNiCr-X(X=Mn,V)high-entropy alloy was prepared by mechanical alloying combined with vacuum hot-pressing sintering technology,and the microstructure,mechanical properties and tribology performance under different conditions of the two high-entropy alloys were systematically studied.Research indicated:The relative density of bulk FeCoNiCr-X(X=Mn,V)alloy prepared by mechanical alloying combined with vacuum hot pressing sintering technology was above 99%.FeCoNiCr Mn high-entropy alloy was a single FCC phase with uniform surface.The average hardness of the alloy was183HV,the compressive strength of the material was 228MPa,and the tensile strength was 686MPa.The main phase of the FeCoNiCrV high-entropy alloy was the FCC phase,and a large number of protruding hard phases?(Cr-V)were precipitated on the surface.The average hardness of the alloy was 975HV,the compressive strength was726MPa,and the tensile strength was 237MPa.FeCoNiCr Mn high-entropy alloy had better tensile properties than FeCoNiCrV.The main fracture mode of FeCoNiCr Mn tensile was dimple-like ductile fracture;the main fracture mode of FeCoNiCrV tensile was brittle dissociation surface fracture combined with a small amount of dimple fracture.Under dry sliding friction conditions at room temperature,when counterpart was Si3N4,FeCoNiCr-X(X=Mn,V)high-entropy alloy had the best tribological performance,and was less affected by the load,and the wear rate is always the lowest,respectively 1.298×10-4mm3/Nm,0.718×10-4mm3/Nm,showing excellent wear resistance.For FeCoNiCr Mn/Si3N4,the main wear mechanisms were adhesive wear,slight fatigue wear and oxidative wear.For FeCoNiCrV/Si3N4,the main wear mechanisms were fatigue wear,adhesive wear and oxidative wear.In a high temperature environment,with the temperature increasing,the wear rate of FeCoNiCrV decreased significantly,and its high temperature wear resistance was better than FeCoNiCr Mn.Especially at 800?,the wear rate of FeCoNiCrV was 20 times lower than FeCoNiCr Mn,and the wear rate was 0.289×10-4mm3/Nm.The main wear mechanism of FeCoNiCrV high-entropy alloy from 25? to 200? was oxidative wear,adhesive wear and fatigue spalling.The degree of surface wear decreased with the increase of temperature.At 800?,the wear mechanism was a single oxidative wear.Under deionized water conditions,the wear resistance of FeCoNiCrV was also better than FeCoNiCr Mn,and the wear rate ranged from 0.26g/m3to 0.3 g/m3.When the FeCoNiCrV alloy surface was hard,the boundary water film lubrication effect was obvious,and the anti-friction and anti-wear effect was obvious.The lubrication mechanism of FeCoNiCrV was boundary lubrication,the lubrication effect was obvious,and the main wear mechanism was micro-furrow wear.Under the condition of liquid paraffin lubrication,the wear rate of FeCoNiCr-X(X=Mn,V)was very low.The wear rate ranged from 0.07g/m3to 0.16g/m3,and from0.02g/m3to 0.03g/m3.Under the protection of oil lubrication,the wear resistance of FeCoNiCrV was still better.The lubrication mechanism of FeCoNiCrV was hydrodynamic lubrication.As the load increased,the micro-furrow wear of the wear machine turned into oxidative wear. |
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