Microstructure And Corrosion Resistance Properties Of Cucrfenimn Based High Entropy Alloys

In this study, three kinds of CuCrFeNiMn high entropy alloy systems, which areCuCr2Fe2Ni2Mn2Tix, CuCryFe2Ni2Mn2and CuxCr2Fe2NiyMn2were prepared by usingnon-consumable vacuum arc furnace.The X-ray diffraction(XRD) and scanningelectron microscopy(SEM) were used to analyze the crystal structures andmicrostructures respectively. The Vickers hardness was used to investigate themechanical properties while the immersion test and electrochemical experiment wereused to characterize the corrosion resistance of three alloy systems in nitric acid withdifferent concentrations(2mass%,10mass%,30mass%) and3.5mass%sodium chioridesolution and were compared with1Cr18Ni9Ti stainless. The experimental resultsshowed that:Cu0.3Cr2Fe2Ni3Mn2Nb（xx=0,0.2,0.4）high entropy alloys were mainly composedwith FCC crystal structure,while Cr2Fe2Ni3Mn2Nbx（x=0.5,1.0,1.5）alloys weremainly composed with FCC+BCC hybrid structure.Increasing Nb content inalloys,decrease the diffraction peak intensity of FCC structure,but increase thehardeness of alloys.And some different primary intergranular phase were precipatedfrom the both of alloys system.For CuxCr2Fe2Ni3Mn2Nb0.4Mo0.2（x=0,0.1,0.2,0.3）alloys system, when x=0.1,0.2,the alloys were composed with single FCC structureand some short clavite intergranular primary phase. When x=0,0.3,however,the alloyscomposed with FCC+BCC hybrid structure and intergranular precipitate showedshort rod and acicular primary phase. With the increase of Cu content in alloys, thehardness of alloys decreases firstly and then increases.But there is little difference inhardeness among three kind of CuxCr2Fe2Ni3Mn2Nb0.4Mo0.2.The experimental results about the corrosion resistance ofCu0.3Cr2Fe2Ni3Mn2Nbxand Cr2Fe2Ni3Mn2Nbxin nitric acid with differentconcentrations(2mass%,10mass%,30mass%) and3.5mass%sodium chioridesolution,it is able to improve the corrosion the corrosion resistance of alloys byadding an appropriate amount of Nb. A3alloy shows the best corrosion resistance among three kinds alloys both in2mass%,10mass%and30mass%nitric acid and3.5mass%sodium chioride solution sodium chioride solution. The corrosionresistance in sodium chioride solution is better and in in nitric acid is comparable tothat of1Cr18Ni9Ti stainless. But significantly higher Nb content in alloys isunfavourable to the corrosion resistance of alloys.With increasing of the Cu content, the corrosion rate ofCuxCr2Fe2Ni3Mn2Nb0.4Mo0.2alloys in nitric acid with various concentrations(2mass%,10mass%,30mass%) and3.5mass%sodium chioride solution decreasedfirstly and then increased. T2alloys shows the best corrosion resistance among threekinds of alloy,which is better in3.5mass%sodium chioride solution and similar in10mass%and30mass%nitric acid to that of1Cr18Ni9Ti stainless.