Mechanical properties and fracture mechanism of as-cast MnFeCoCuNix high-entropy alloys  

铸态MnFeCoCuNix高熵合金的力学性能与断裂机理

作　　者：Cheng-yan ZHU Hao WU He-guo ZHU Xiang-dong LI Chun-lei TU Zong-han XIE 朱成艳;伍昊;朱和国;李向东;涂春磊;谢宗翰(南京理工大学材料科学与工程学院,南京210094;东南大学机械学院,南京211189;南京理工大学机械学院,南京210094;School of Mechanical Engineering,University of Adelaide,SA 5005,Australia;School of Engineering,Edith Cowan University,WA 6027,Australia)

机构地区：[1]School of Materials Science and Engineering,Nanjing University of Science and Technology,Nanjing 210094,China [2]School of Mechanical Engineering,Southeast University,Nanjing 211189,China [3]School of Mechanical Engineering,Nanjing University of Science and Technology,Nanjing 210094,China [4]School of Mechanical Engineering,University of Adelaide,SA 5005,Australia [5]School of Engineering,Edith Cowan University,WA 6027,Australia

出　　处：《Transactions of Nonferrous Metals Society of China》2021年第1期222-231,共10页中国有色金属学报（英文版）

基　　金：The authors are grateful for the financial supports from the Jiangsu Provincial Science and Technology Plan Project,China(BE2018753/KJ185629);the National Natural Science Foundation of China(51571118);the 2020 Extracurricular Academic Research Fund for College Students of Nanjing University of Science and Technology,China.Zong-han XIE acknowledges the support of the Australian Research Council Discovery Projects.

摘　　要：MnFeCoCuNix high-entropy alloys(HEAs)with different Ni contents were fabricated by vacuum induction melting.XRD and SEM−EDS were used to analyze the phase constitution and structure,and the tensile properties of the samples were determined using a universal tensile tester.The results show that the HEAs consist of a dual-phase structure,in which FCC1 phase is rich in Fe and Co,while the FCC2 phase has high contents of Cu and Mn.As Ni content increases,the segregation of Cu decreases,accompanied by the decrease of FCC2 phase.Moreover,the tensile strength of the HEAs increases first and then decreases,and the elongation increases slightly.This is attributed to the combined effect of interface strengthening and solid solution strengthening.The in-situ stretched MnFeCoCuNi0.5 alloy shows obvious neck shrinkage during the tensile fracture process.In the initial deformation stage,the slip lines show different morphologies in the dual-phase structure.However,in the later stage,the surface slip lines become longer and denser due to the redistribution of atoms and the re-separation of the dissolved phase.采用真空感应熔炼法制备不同Ni含量的MnFeCoCuNix高熵合金。利用X射线衍射仪、扫描电镜以及能谱仪分析材料的相组成和结构,利用万能拉伸试验机测定试样的拉伸性能。结果表明,该高熵合金体系具有双相结构。其中,FCC1相富含Fe和Co,而FCC2相富含Cu和Mn。随着Ni含量的增加,Cu的偏析减少,伴随着FCC2相的减少。在界面强化和固溶强化的共同作用下,抗拉强度先升高后降低,而伸长率略有增加。对MnFeCoCuNi0.5合金进行原位拉伸试验,发现其在拉伸断裂过程中产生明显的颈缩。在初始变形阶段,双相结构中滑移线的形态不同;在变形后期原子的再分布和溶解相的再分离使得表面滑移线更加细长和致密。

关 键 词：high-entropy alloys dual-phase structure mechanical properties in-situ stretching fracture mechanism 

分 类 号：TG139[一般工业技术—材料科学与工程]