Unveiling anneal hardening in dilute Al-doped Al_(x)CoCrFeMnNi(x = 0,0.1) high-entropy alloys  

作　　者：Q.Cheng X.D.Xu P.Xie L.L.Han J.Y.He X.Q.Li J.Zhang Z.T.Li Y.P.Li B.Liu T.G.Nieh M.W.Chen J.H.Chen 

机构地区：[1]Centre for High Resolution Electron Microscopy,College of Materials Science and Engineering,Hunan University,Changsha 410082,China [2]State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China [3]Applied Materials Physics,Department of Materials Science and Engineering,KTH-Royal Institute of Technology,Stockholm SE,10044,Sweden [4]Department of Materials Science and Engineering,University of Tennessee,Knoxville,TN,37996,United States [5]Department of Materials Science and Engineering,Johns Hopkins University,Baltimore,MD 21214,USA

出　　处：《Journal of Materials Science & Technology》2021年第32期270-277,共8页材料科学技术（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (No. 52001120);the Fundamental Research Funds for the Central Universities (No. 531118010450);the Hundred Talent Program of Hunan Province;the State Key Laboratory of Powder Metallurgy,Central South University,Changsha;the State Key Laboratory of Advanced Metals and Materials(No. 2021-Z09);University of Science&Technology Beijing,China;supported by the National Natural Science Foundation of China (No. 51801060);supported by the Swedish Research Council;supported by the National Science Foundation under Contract (No. DMR-1408722);sponsored by the Whiting School of Engineering;Johns Hopkins University;funded by the National Key Research and Development Program of China (No. 2016YFB0300801);the National NaturalScience Foundation of China (Nos. 51831004, 11427806, 51671082,51471067)。

摘　　要：Anneal hardening has been one of the approaches to improve mechanical properties of solid solution alloys with the face-centered cubic(FCC) structure,whereby a considerable strengthening can be attained by annealing of cold-worked alloys below the recrystallization temperature(T_(rx)).Microscopically,this hardening effect has been ascribed to several mechanisms,i.e.solute segregation to defects(dislocation and stacking fault) and short-range chemical ordering,etc.However,none of these mechanisms can well explain the anneal hardening recently observed in phase-pure and coarse-grained FCC-structured high-entropy alloys(HEAs).Here we report the observations,using high-resolution electron channeling contrast imaging and transmission electron microscopy,of profuse and stable dislocation substructures in a cold-rolled CoCrFeMnNi HEA subject to an annealing below T_(rx).The dislocation substructures are observed to be thermally stable up to T_(rx),which could arise from the chemical complexity of the high-entropy system where certain elemental diffusion retardation occurs.The microstructure feature is markedly different from that of conventional dilute solid solution alloys,in which dislocation substructures gradually vanish by recovery during annealing,leading to a strength drop.Furthermore,dilute addition of 2 at.% Al leads to a reduction in both microhardness and yield strength of the cold-rolled and subsequently annealed(≤500℃) HEA.This Al induced softening effect,could be associated with the anisotropic formation of dislocation substructure,resulting from enhanced dislocation planar slip due to glide plane softening effect.These findings suggest that the strength of HEAs can be tailored through the anneal hardening effect from dislocation substructure strengthening.

关 键 词：Annealing hardening Dislocation substructure strengthening High-entropy alloy Solid solution structure 

分 类 号：TG156.2[金属学及工艺—热处理]