Thermal stability and deformation mechanisms in Ni-Co-Fe-Cr-Al-Ti-Nb-type nanoparticle-strengthened high-entropy alloys  

作　　者：J.X.Hou J.Y.Zhang J.X.Zhang J.H.Luan Y.X.Wang B.X.Cao Y.L.Zhao Z.B.Jiao X.J.Liu W.W.Song P.K.Liaw T.Yang 

机构地区：[1]Department of Materials Science and Engineering,Hong Kong Institute for Advanced Study,City University of Hong Kong,Hong Kong,China [2]School of Materials Science and Engineering,Harbin Institute of Technology(Shenzhen),Shenzhen 518055,China [3]Department of Mechanical Engineering,The Hong Kong Polytechnic University,Hong Kong,China [4]Steel Institute,RWTH Aachen University,Aachen 52072,Germany [5]Institute of Materials Engineering,University of Kassel,Kassel 334125,Germany [6]Department of Materials Science and Engineering,The University of Tennessee,Knoxville,TN 37996-2200,USA [7]City University of Hong Kong,China

出　　处：《Journal of Materials Science & Technology》2023年第36期171-183,共13页材料科学技术（英文版）

基　　金：financially supported by the National Natu-ral Science Foundation of Chin a(Grant Nos.52101135,52101151,and 52171162);the Hong Kong Research Grant Coun-cil,University Grants Committee(RGC)with CityU grants Nos 21205621 and15227121;Wealso thankthefinancialsupport from the Shenzhen Science and Technology Program(Grant No.RCBS20210609103202012);PKL very much appreciates the sup-port from(1)the National Science Foundation(Nos.DMR-1611180,1809640,and 2226508);(2)the US Army Research Office(Nos.W911NF-13-1-0438 and W911NF-19-2-0049).

摘　　要：The precipitate morphologies,coarsening kinetics,elemental partitioning behaviors,grain structures,and tensile properties were explored in detail for L1_(2)-strengthened Ni_(39.9)Co_(20)Fe_(15)Cr_(15)Al_(6)Ti_(4-x)Nb_(x)B_(0.1)(x=0 at.%,2 at.%,and 4 at.%)high-entropy alloys(HEAs).By substituting Ti with Nb,the spheroidal-to-cuboidal precipitate morphological transition,increase in the coarsening kinetics,and phase decomposition upon aging at 800°C occurred.The excessive addition of Nb brings about the grain boundary precipitation of an Nb-rich phase along with the phase decomposition from the L1_(2)to lamellar-structured D019 phase upon the long-term aging duration.By partially substituting Ti with Nb,the chemically complex and thermally stable L12 phase with a composition of(Ni_(58.8)Co_(9.8)Fe_(2.7))(Al_(12.7)Ti_(5.8)Nb_(7.5)Cr_(2.3))ensures the stable phase structure and clean grain boundaries,which guarantees the superb high-temperature mechanical properties(791±7 MPa for yielding and 1013±11 MPa for failure)at 700℃.Stacking faults(SFs)were observed to prevail during the plastic deformation,offering a high work-hardening capability at 700°C.An anomalous rise in the yield strength at 800℃was found,which could be ascribed to the multi-layered super-partial dislocations with a cross-slip configuration within the L1_(2)particles.

关 键 词：High-entropy alloys Coarsening kinetics Coherent precipitation strengthening Mechanical properties 

分 类 号：TG146.11[一般工业技术—材料科学与工程] TB383.1[金属学及工艺—金属材料]