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Novel atomic-scale mechanism of incipient plasticity in a chemically complex CrCoNi medium-entropy alloy associated with inhomogeneity in local chemical environment

文献类型：期刊论文

作者Cao FH(曹富华)1,2,3; Wang YJ(王云江)1,2,3; Dai LH(戴兰宏)1,2,3
刊名ACTA MATERIALIA
出版日期2020-08-01
卷号194页码:283-294
ISSN号1359-6454
关键词Dislocation nucleation Medium-entropy alloy Local chemical order Molecular dynamics Density functional theory
DOI10.1016/j.actamat.2020.05.042
英文摘要Understanding the incipient plastic mechanism in metals is critical for their associated mechanical properties. While heterogeneous dislocation nucleation from pre-existing defects constitutes the most prevalent onset mechanism of plasticity in the conventional solutions, such a scenario may break down in the recently emerging chemically-disordered high/medium entropy alloys (HEAs/MEAs), owing to their unique multiple-component feature and the inevitable inhomogeneity in local atomic environments. Here, classical molecular dynamics simulations and first-principles density functional theory calculations are carried out to study the atomic-scale mechanisms governing the incipient plasticity in a prototypical chemically complex face-centered cubic (fcc) CrCoNi MEA. Dislocation nucleation is found to occur preferentially at an energetically unstable defect cluster with body-centered cubic like (bcc-like) atomic environment as a precursor, after certain deformation before plasticity, which is in contrast with the usual mechanism of heterogeneous dislocation nucleation in the conventional solute solution metals. The minimum energy pathway of dislocation nucleation from a bcc precursor is discussed to rationalize the usual phenomenon. First-principles athermal quasi-static compression test validates the mechanism suggested by atomistic simulations. Further electronic structure analysis suggests that the local bcc-like defect cluster is related to the localized electronic behaviors of Cr atoms and the weak Cr-Cr bonding, which promote the dislocation nucleation and therefore the incipient plasticity of CrCoNi MEA. The atomic and electronic insights reported here highlight the significant role of local chemical order in determining the mechanical property, and shed light on the strategy of optimizing mechanical performance via tailoring composition and local atomic arrangement in the generic highly concentrated solutions. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
分类号一类
WOS关键词SURFACE DISLOCATION NUCLEATION ; HYDROGEN EMBRITTLEMENT ; ACTIVATION VOLUME ; RATE SENSITIVITY ; SIZE DEPENDENCE ; DEFORMATION ; RESISTANCE ; ALUMINUM ; BEHAVIOR ; METALS
WOS研究方向Materials Science ; Metallurgy & Metallurgical Engineering
语种英语
WOS记录号WOS:000542971400024
资助机构NSFC Basic Science Center Program for ''Multiscale Problems in Nonlinear Mechanics''[11988102] ; NSFC[11790292] ; NSFC[11672299] ; National Key Research and Development Program of China[2017YFB0702003] ; National Key Research and Development Program of China[2017YFB0701502] ; Strategic Priority Research Program[XDB22040302] ; Strategic Priority Research Program[XDB22040303] ; Key Research Program of Frontier Sciences[QYZDJSSW-JSC011] ; Science Challenge Project[TZ2016001] ; Youth Promotion Association of Chinese Academy of Sciences[2017025] ; opening project of State Key Laboratory of Explosion Science and Technology[KFJJ18-14 M]
其他责任者Wang, Yun-Jiang ; Dai, Lan-Hong
源URL[http://dspace.imech.ac.cn/handle/311007/84736]  
专题力学研究所_非线性力学国家重点实验室
作者单位1.CAS Ctr Excellence Complex Syst Mech, Beijing 100190, Peoples R China
2.Univ Chinese Acad Sci, Sch Engn Sci, Beijing 101408, Peoples R China;
3.Chinese Acad Sci, Inst Mech, State Key Lab Nonlinear Mech, Beijing 100190, Peoples R China;
推荐引用方式
GB/T 7714		 Cao FH,Wang YJ,Dai LH. Novel atomic-scale mechanism of incipient plasticity in a chemically complex CrCoNi medium-entropy alloy associated with inhomogeneity in local chemical environment[J]. ACTA MATERIALIA,2020,194:283-294.
APA 曹富华,王云江,&戴兰宏.(2020).Novel atomic-scale mechanism of incipient plasticity in a chemically complex CrCoNi medium-entropy alloy associated with inhomogeneity in local chemical environment.ACTA MATERIALIA,194,283-294.
MLA 曹富华,et al."Novel atomic-scale mechanism of incipient plasticity in a chemically complex CrCoNi medium-entropy alloy associated with inhomogeneity in local chemical environment".ACTA MATERIALIA 194(2020):283-294.

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来源：力学研究所

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