Study On Preparation And Performance Of CrFeCoNiTi_x High Entropy Alloys

High entropy alloys consists of five or more than five kind of metal elements,and various kinds of elements according to the mole ratio of or approximate mole ratio form a simple structure of solid solution alloy material.Metal element types increase improved multigroup alloy internal chaos in the overall level,at the same time to increase the entropy of mixing system,which called the high entropy effect.Effect of high entropy can make alloy on the organization structure form has a simple lattice structure of solid solution phase,at the same time accompanied by a small number of compound phase.This kind of high entropy alloys will be both solid solution strengthening in terms of performance improvement,the second dispersion strengthening and fine-grain strengthening mechanism,in order to improve the comprehensive performance of alloy.So most high entropy alloys have high strength,high hardness,wear resistance,good corrosion resistance,oxidation resistance is strong,fine properties such as high temperature oxidation resistance.The above performance makes the high entropy alloys have good development potential and broad application prospects.In this work,CoCrFeNiTi high entropy alloys with designed ratio of selection of Co、Cr、Fe、Ni、Ti were synthesized by mechanical alloying and Vacuum smelting method,Vacuum hot pressing and spark plasma sintering.Phase structures and microstructures of alloys were investigated by using OM,XRD,SEM and EDS.Meanwhile,the Vickers hardness,compressive strength,fracture morphology and polarization curve of the alloys were also tested.Experimental results show that the vacuum smelting sample method,along with the increase of the content of Ti elements,structure of alloy by the FCC structure to BCC structure transformation,and a small amount of HCP structure generated at the same time.By mechanical alloying of mixed powder,when alloying time reach after 10 h,increasing the ball milling time has a little effect on powderparticle size,and consistent with the particle size.And the microstructure of Cr Co Fe Ni Tix high entropy alloy prepared by SPS possessed reticular structures,and formed a simple FCC and BCC lattice structure,also accompanied by precipitation of intermetallic compounds.When Ti content was much higher,a small amount of Laves phase was precipitated.Vacuum hot pressing sintering material is given priority to with face-centered cubic phase,and some other phase.CrFeCoNiTi_x high entropy alloys Vickers hardness increase gradually with the increase of content of Ti element,when Ti content is 1.0 Vickers hardness value maximum.Compression experiment,the same is Ti content reaches 1.0 compression strength,the largest is brittle fracture.Compared to the sulfuric acid solution,CrFeCoNiTi high entropy alloy was eroded easier by hydrochloric acid,having a anti-acid corrosion at low Ti content.