Precipitation and heterogeneous strengthened CoCrNi-based medium entropy alloy with excellent strength-ductility combination from room to cryogenic temperatures

作     者：XIE Yu ZHAO PengCheng TONG YongGang TAN JianPing SUN BinHan CUI Yan WANG RunZi ZHANG XianCheng TU ShanTung 

作者机构：Key Laboratory of Pressure Systems and SafetyMinistry of EducationSchool of Mechanical and Power EngineeringEast China University of Science and TechnologyShanghai 200237China College of Automobile and Mechanical EngineeringChangsha University of Science and TechnologyChangsha 410114China Key Laboratory for Advanced Materials and Feringa Nobel Prize Scientist Joint Research CenterInstitute of Fine ChemicalsSchool of Chemistry&Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China 

出 版 物：《Science China(Technological Sciences)》 (中国科学（技术科学英文版）)

年 卷 期：2022年第65卷第8期

页      面：1780-1797页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.52105144,52075174,51725503 and 52005184) Shanghai Super Postdoctoral Incentive Plan(Grant No.2020134) China Postdoctoral Science Foundation(Grant No.2021M701201) Shanghai Sailing Program(Grant No.20YF1409600) 

主　　题：medium entropy alloy cryogenic temperature heterogeneous structure precipitation strengthening twinning 

摘      要：The improved understandings of the mechanical properties as well as deformation mechanisms at cryogenic temperatures are the prerequisite for realizing the application of any new engineering materials to cryogenic ***,a(CoCrNi)_(94)Al_(3)Ti_(3) medium entropy alloy(MEA)with nanoscale L12 coherent precipitates and heterogeneous grain structures was prepared by codoping Al and Ti elements with subsequent cold rolling and heat treatment *** mechanical properties were evaluated at the temperature range of 293–113 *** ultimate strength of the MEA increases almost linearly from 1326 to 1695 MPa as the temperature decreases from 293 to 113 K,while the total elongation remains approximately constant of~35%.The underlying deformation and strengthening mechanisms were investigated using various characterization *** to the effect of co-doped Al/Ti on channel width of the matrix and the increasing critical twinning stress induced by heterogeneous ultrafine grain size,the formation of deformation twins is inhibited at all ***,only a slight increase of the deformation twins and stacking faults in the deformed specimens with a decreasing temperature,which leads to the relative temperature-independence of the *** dislocation cutting mechanism of L1_(2) coherent precipitates and the heterodeformation induced(HDI)hardening both significantly contribute to the strain hardening so that an excellent combination of strength and ductility is ***,the evolution of lattice friction stress with deformation temperature is determined by quantitative analysis,indicating an approximately linear relationship between the lattice friction and *** present work provides new insights into the strategy of achieving outstanding strength-ductility synergy of the MEA under the wide temperature range by coupling heterogeneous ultrafine-grained structure and coherent precipitation strategy.