Simulation And Experimental Study On Friction And Wear Characteristics Of High-entropy Alloy Feconicrmn

High-entropy alloys（HEAs）have been the focus of attention in the field of materials science and engineering due to their potentially ideal properties.The large-scale application of HEAs cannot be separated from multi-disciplinary research,including the related on tribological properties.In this work,the single-phase high-entropy alloy is taken as the research object,and physical tests are combined with numerical simulations to study the tribological behavior of HEAs under lubrication conditions systematically.In order to study the friction and wear behavior of a single-phase face-centered cubic（FCC）FeCoNiCrMn（285 HV）under MoS₂-oil（with 1 wt%MoS₂ contained）lubrication conditions,a ball-on-disk reciprocating sliding arrangement is used in the friction test,and a GCr15 ball（780 HV）is selected as the counterpart.Based on single-factor（sliding speed and load）modeling tests（15 min）at room temperature（RT）,FeCoNiCrMn wear indicators at various conditions are extracted and analyzed,and the numerical model of FeCoNiCrMn Archard wear（Correlation coefficient R=0.89）is established.The static contact simulation is performed using Workbench to obtain the stress and deformation of the friction pair under each load（the error is around 1%from the theoretical calculation）.According to this,the displacement conditions of the transient structure simulation are determined by the deformation coordination equation.The transient structure simulation results show that under the same load conditions,the dynamic friction contact pressure of the FeCoNiCrMn-GCr15 is higher than that under static loading,which becomes the basis for the subsequent wear model modification;with the increase of load,both the transient friction stress and the surface temperature of FeCoNiCrMn shows an increasing trend.For the same load with different sliding speeds,the dynamic friction contact pressure has small changes,but the contact pressure in the dynamic friction stage is greater than that in the static loading stage;the increase in speed reduces the transient friction stress,but increases the maximum temperature of the FeCoNiCrMn surface.In addition,the analysis results of transient results reveal that as the relative sliding speed of the friction pair increased,the area frictional heat influences of the contact area gradually decreases.The wear model is refitted according to the dynamic friction contact pressure by comparing the curve of the fitted value with the experimental value,and finally the modified Archard equation is obtained（R=0.96）.The APDL is used to definite the Archard model,and the FeCoNiCrMn wear volume simulation is performed.The results show that the error between the wear value and the experimental value is about 10-15%,which is due to the complexity（system characteristics and time-varying characteristics）of the real friction test and the necessary treatment for the simulation model（simplification of mesh model and boundary conditions）.The tribological experiment adopts the strategy of orthogonal test and comparative test,and L25（56）orthogonal wear tests are carried out for speed V_rel（4.167～20.833 mm/s）,load FN（10～50 N）,temperature T（RT-140℃）and time t（5-20 min）.According to orthogonal test results,multivariate repeated measures ANOVA（analysis of variance）is performed,and further comparative experiments are conducted for V_rel,FN and T.Energy dispersive spectrometer（EDS）and scanning electron microscope（SEM）are applied to characterize the surface morphology of wear scar and its element distribution.The ANOVA demonstrates that V_rel,FN and t have the most significant influence（P<0.01）on the average friction coefficient f.V_rel and FN are found as the momentous effect（P<0.01）on wear volume ΔV.T（≥50℃）has positive correlation with f and ΔV,while both V_rel and FN have negative correlation with f.The detailed characterization reveals the domination of abrasive wear with oxidative wear detected,which is attributed to the large hardness difference of the friction pair.Fatigue wear and delamination wear are experienced gradually at higher speeds(V_rel≥12.500 mm/s)and loading levels（FN≥40 N）.It is weakened by elevated temperature that the lubrication effect of MoS₂-oil and the mechanical properties of FeCoNiCrMn matrix,which intensifies abrasive wear.Additionally,the increase in speed,the increase in load,and the suppression of temperature rise all contributes to the reduction of the average friction coefficient,and the large hardness difference between the friction pair materials makes the main damage of FeCoNiCrMn under MoS₂-oil lubrication become abrasion wear.