| High entropy alloy is a new multi-element alloy with excellent properties of magnetic and electrical properties,high strength,high hardness,high wear resistance,oxidation resistance,corrosion resistance and thermal stability and so on,meanwhile,it has a wide application prospect.However,most of the studies on multi-element high-entropy alloys are concentrated in the fields of mechanical properties,wear resistance and thermal stability.However,there are still few studies on the electrochemical corrosion behavior of high-entropy alloys.The superior low temperature toughness and strength of high-entropy alloys have been proven,and the research on their corrosion resistance will provide strong support for its wide application.Thus,the experimental study of the corrosive properties of high-entropy alloys has a forward-looking and application value.Therefore,this paper investigated the corrosion behavior of FeNi2CoMo0.2V0.5 as-cast high-entropy alloys by immersion loss-of-weight test and macroscopic and Local-electrochemical methods.At the same time,the deformation and high-pressure torsion deformation of as-cast high-entropy alloys were investigated.The effects of severe plastic deformation on the corrosion resistance of high-entropy alloys were also studied.In addition,microstructure analysis was carried out by TEM,SEM and EBSD.The hardness of pure nickel,as-cast high-entropy alloy,Rolling state high-entropy alloy and HPTed high-entropy alloy were compared.Finally,through a large number of experimental results,Analysis,combined with microstructure analysis,corrosion morphology analysis,the electrochemical corrosion behavior of high-entropy alloys and high-entropy alloys in the deformed state were obtained.By comparing the results of macroscopic electrochemical experiments and the corrosion topography of three different kinds of electrolyte solutions of pure nickel with as-cast high-entropy alloy in 3.5%NaCl solution,1 M NaOH solution and 2%HNO3 solution,it can be concluded that the corrosion resistance of pure nickel in 3.5%NaCl solution and 1 M NaOH solution is better than that of as-cast high-entropy alloy,and the corrosion resistance in 2%HNO3 solution is not as good as that of as-cast high-entropy alloy.This is in good agreement with the results of immersion corrosion weight loss test.However,the corrosion rate of pure nickel is higher than that of high-entropy alloy in 1M NaOH solution for 30 days.Similarly,macroscopic electrochemical experiments and corrosion patterns of high entropy alloys before and after Rolling in 3.5%NaCl solution,1%NaOH solution and 2%HNO3 solution were compared.The corrosion resistance of Rolling state high-entropy alloy in 3.5%NaCl solution and 1M NaOH solution is better than that of as-cast high-entropy alloy,however,its corrosion resistance in 2%HNO3 solution is not as good as that of as-cast high-entropy alloy.The high-entropy alloy has obvious grain refinement after high-pressure torsion treatment.However,the grain size distribution is still not uniform with the initial state.The crystal contains a large number of high-density dislocation structures.The experimental results of microhardness show that the hardness of the high-entropy alloy sample after the high-pressure torsion is obviously improved,and the hardness distribution of the initial sample is relatively uniform,about 178HV,HPTed distribution is uneven,the center of the smallest hardness,about 267HV;away from the center,the higher the hardness,the highest 493HV;immersion corrosion test results show that HPTed high entropy alloy in 3.5%NaCl solution,1M NaOH solution and The corrosion rate of 2%HNO3 solution in these three different kinds of electrolyte solutions is lower than that of as-cast high-entropy alloy.The macro-electrochemical experiments show that the corrosion resistance of high-entropy alloy after HPT in 3.5%NaCl solution decreased.However,The corrosion resistance of HPTed high entropy alloy in 1M NaOH solution is improved,while the corrosion resistance of HPT high entropy alloy in 2%HN03 solution is almost no difference.Electrochemical corrosion experiments in the different areas in the HPTed high entropy alloy sample show that the corrosion resistance of the edge region is superior to that of the central region,which is the same in the above three different electrolyte solutions.This is consistent with the results of the Scanning Kelvin probe,the potential volt of HPTed high-entropy alloy samples in the center area is low,edge potential is high,this interpreted the difference in corrosion behavior between center and edge of high-entropy alloy sample from the local scale. |
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