Design and optimization of the composition and mechanical properties for non-equiatomic CoCrNi medium-entropy alloys  

作　　者：J.X.Yan Z.J.Zhang P.Zhang J.H.Liu H.Yu Q.M.Hu J.B.Yang Z.F.Zhang 

机构地区：[1]Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China [2]School of Materials Science and Engineering,Chongqing Jiaotong University,Chongqing 400074,China [3]chool of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China [4]School of Materials Science and Engineering,Northeastern University,Shenyang 110819,China [5]School of Information Science and Engineering,Shenyang University of Technology,Shenyang 111003,China

出　　处：《Journal of Materials Science & Technology》2023年第8期232-244,共13页材料科学技术（英文版）

基　　金：We sincerely acknowledge the support of the work by the Na-tional Natural Science Foundation of China(NSFC)(Nos.52130002,52071316,51871223,51771206 and 51571198);the Youth Innova-tion Promotion Association CAS(No.2021192);the KC Wong Education Foundation(No.GJTD-2020-09).

摘　　要：The development of multi-principal element alloys(MPEAs,also called as high-or medium-entropy al-loys,HEAs/MEAs)provides tremendous possibilities for materials innovation.However,designing MPEAs with desirable mechanical properties confronts great challenges due to their vast composition space.In this work,we provide an essential criterion to efficiently screen the CoCrNi MEAs with outstanding strength-ductility combinations.The negative Gibbs free energy difference△E_(FCC-BCC)between the face-centered cubic(FCC)and body-centered cubic(BCC)phases,the enhancement of shear modulus G and the decline of stacking fault energy(SFE)γ_(isf)are combined as three requisites to improve the FCC phase stability,yield strength,deformation mechanisms,work-hardening ability and ductility in the criterion.The effects of chemical composition on△E_(FCC-BCC),G andγisf were investigated with the first principles calculations for Co_(x)Cr_(33)Ni_(67-x),Co_(33)Cr_(y)Ni_(67-y)and Co_(z)Cr_(66-z)Ni_(34)(0≤x,y≤67 and 0≤z≤66)alloys.Based on the essential criterion and the calculation results,the composition space that displays the neg-ative Gibbs free energy difference△E_(FCC-BCC),highest shear modulus G and lowest SFEγ_(isf)was screened with the target on the combination of high strength and excellent ductility.In this context,the optimal composition space of Co-Cr-Ni alloys was predicted as 60 at.%-67 at.%Co,30 at.%-35 at.%Cr and 0 at.%-6 at.%Ni,which coincides well with the previous experimental evidence for Co_(55)Cr_(40)Ni_(5)alloys.The valid-ity of essential criterion is further proved after systematic comparison with numerous experimental data,which demonstrates that the essential criterion can provide significant guidance for the quick exploitation of strong and ductile MEAs and promote the development and application of MPEAs.

关 键 词：Medium-entropy alloys First-principles calculations Phase stability Stacking-fault energy Strength DUCTILITY 

分 类 号：TG139[一般工业技术—材料科学与工程] TG142.71[金属学及工艺—合金]