Strengthening and toughening bulk Ni_(2)CoFeV_(0.5) medium-entropy alloy via thermo-mechanical treatment  

作　　者：Lei Gu Rui Hou Yi Liu Guang Chen Jihua Liu Gong Zheng Ruisheng Zhang Yonghao Zhao 

机构地区：[1]National Key Laboratory of Advanced Casting Technologies,MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology,Engineering Research Center of Materials Behavior and Design,Ministry of Education,Nanjing University of Science and Technology,Nanjing 210094,China

出　　处：《Journal of Materials Science & Technology》2023年第20期19-29,共11页材料科学技术（英文版）

基　　金：supported by the National Key R&D Program of China(Grant No.2021YFA1200203);National Natural Science Foundation of China(Grant Nos.51971112,51225102,92163215,52174364,52101143,51731006,and 12202201);Natural Science Foundation of Jiangsu Province Major Project(Grant No.BK20212009);the Fundamental Research Funds for the Central Universities(Grant Nos.30922010202,30922010711,and 30919011405)。

摘　　要：Single-phase face-centered cubic(fcc)medium-and high-entropy alloys(MEAs/HEAs)have high ductility but low yield strength.In this work,the microstructures of single-phase fcc Ni_(2)CoFeV_(0.5) MEAs were tailored by cold-rolling and subsequent annealing and typical heterogeneous lamella(HL)structures composed of recrystallized micro-grain lamellae(with an averaged grain size of∼4μm)and nonrecrystallized nano-/ultrafine-grain lamellae were obtained.Tensile tests revealed that most HL samples exhibited excellent strength and ductility synergy.The HL sample with∼23 vol%recrystallized grains annealed at 590℃ for 1 h had a high yield strength of 1120 MPa and a good fracture elongation of 12.3%,which increased by 5%and 46%,respectively compared with those of as-rolled sample.Annealing-induced yield strength increase is attributed to high-density annealing twin boundaries(TBs)in the recrystallized grains,the annihilation of mobile dislocations inside the non-recrystallized grains,and extra heterodeformation-induced strengthening produced by the HL structure.Hall-Petch relationship of Ni_(2)CoFeV_(0.5) MEA can be reasonably described by counting both TBs and grain boundaries,with lattice friction stress of 87.3 MPa and coefficient of 722.8 MPaμm1/2.Our work provides optional and controllable solutions for preparing MEAs/HEAs with excellent mechanical properties by low-cost and high-efficiency thermomechanical treatments.

关 键 词：Medium-entropy alloys MICROSTRUCTURES Strength and ductility Heterogeneous lamella structure COLD-ROLLING Annealing 

分 类 号：TG1[金属学及工艺—金属学]