文献类型：期刊文献

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

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

作者：Xie Yu[1];Zhao PengCheng[1];Tong YongGang[2];Tan JianPing[1];Sun BinHan[1];Cui Yan[3,4];Wang RunZi[1];Zhang XianCheng[1];Tu ShanTung[1]

机构：[1]East China Univ Sci & Technol, Sch Mech & Power Engn, Key Lab Pressure Syst & Safety, Minist Educ, Shanghai 200237, Peoples R China;[2]Changsha Univ Sci & Technol, Coll Automobile & Mech Engn, Changsha 410114, Peoples R China;[3]East China Univ Sci & Technol, Key Lab Adv Mat, Sch Chem & Mol Engn, Inst Fine Chem, Shanghai 200237, Peoples R China;[4]East China Univ Sci & Technol, Feringa Nobel Prize Scientist Joint Res Ctr, Sch Chem & Mol Engn, Inst Fine Chem, Shanghai 200237, Peoples R China

年份：2022

卷号：65

期号：8

起止页码：1780

中文期刊名：Science China(Technological Sciences)

外文期刊名：SCIENCE CHINA-TECHNOLOGICAL SCIENCES

收录：CSTPCD;;EI(收录号：20222912384753);Scopus;WOS:【SCI-EXPANDED(收录号:WOS:000824277300001)】；CSCD:【CSCD2021_2022】；PubMed;

基金：This work was 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), and Shanghai Sailing Program (Grant No. 20YF1409600).

语种：英文

中文关键词：medium entropy alloy;cryogenic temperature;heterogeneous structure;precipitation strengthening;twinning

外文关键词：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 industries.Here,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 processes.The mechanical properties were evaluated at the temperature range of 293–113 K.The 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 techniques.Due 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 temperatures.Consequently,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 ductility.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 obtained.Additionally,the evolution of lattice friction stress with deformation temperature is determined by quantitative analysis,indicating an approximately linear relationship between the lattice friction and temperature.The 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.
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 industries. Here, a (CoCrNi)(94)Al3Ti3 medium entropy alloy (MEA) with nanoscale L1(2) coherent precipitates and heterogeneous grain structures was prepared by co-doping Al and Ti elements with subsequent cold rolling and heat treatment processes. The mechanical properties were evaluated at the temperature range of 293-113 K. The 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 similar to 35%. The underlying deformation and strengthening mechanisms were investigated using various characterization techniques. Due 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 temperatures. Consequently, 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 ductility. 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 obtained. Additionally, the evolution of lattice friction stress with deformation temperature is determined by quantitative analysis, indicating an approximately linear relationship between the lattice friction and temperature. The 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.