Study On The Microstructure And Properties Of High-Entropy Alloys With Multi-Principal Elements

High entropy alloys with multi-principal elements are a novel concept for alloy design, which breaks through the traditional alloy design on the base of one or two major alloy elements, and become one of the hot research topics in materials science and engineering. High entropy alloys are composed of at least five elements which have equal mole or near equal mole ratios. High entropy effects arising from the mixture of multi-principal elements promote the formation of simple microstructures in the alloys. High entropy alloys have aroused the scholar's attention and enthusiastic exploration all over the world because of their good performances in many aspects.In this thesis, eight common elements Al,Fe,Cu,Co,Ni,Cr,Ti and V were selected and seven high entropy alloys AlFeCuCoCr,CuCoCrNiFe,AlFeCuCoNiCr,AlFeCuCoNiCrTi0.5,AlFeCoCrNi,AlFeCuNiCrV and AlFeCuCoNiCrTiV were prepared by vacuum arc funace. Their microstructures, surface morphologies, phase structures and formation mechanism were investigated. And their hardness, softening resistance after high temperature annealing, thermal properties and corrosion resistance were studied. The results are showing as followed:(1) All the seven high entropy alloys form into bcc or fcc or bcc+fcc structures, only a little ordered solid solution structures are observed.(2) Al element promotes the formation of bcc structure, which will increase the hardness and strength of high entropy alloys. Except CuCoCrNiFe high entropy alloy which is without Al element exhibits low hardness, all the others exhibit high hardness in the range from 700 HVto1200HV.(3) Cu element segregates in the interdendrite and plays a leading role in the(4) High entropy alloys perform good softening resistance after 800℃high temperature annealing, and CuCoCrNiFe,AlFeCuCoNiCr. AlFeCoCrNi,AlFeCuCoNiCrTiV alloys exhibit higher hardness because of their precipitation hardening properties.(5) High entropy alloys perform good thermostability properties.(6) High entropy alloys perform good corrosion resistance. Except AlFeCuNiCrV alloy, all the others have better corrosion resistance than the 304 stainless steel.