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Dynamically reinforced heterogeneous grain structure prolongs ductility in a medium-entropy alloy with gigapascal yield strength

文献类型：期刊论文

作者Yang MX(杨沐鑫); Yan DS(严定舜); Yuan FP(袁福平); Jiang P(姜萍); Ma E; Wu XL(武晓雷)
刊名PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
出版日期2018-07-10
卷号115期号:28页码:7224-7229
关键词heterogeneous grain structure ductility medium-entropy alloy back stress hardening
ISSN号0027-8424
DOI10.1073/pnas.1807817115
英文摘要Ductility, i. e., uniform strain achievable in uniaxial tension, diminishes for materials with very high yield strength. Even for the CrCoNi medium-entropy alloy (MEA), which has a simple facecentered cubic (FCC) structure that would bode well for high ductility, the fine grains processed to achieve gigapascal strength exhaust the strain hardening ability such that, after yielding, the uniform tensile strain is as low as similar to 2%. Here we purposely deploy, in this MEA, a three-level heterogeneous grain structure (HGS) with grain sizes spanning the nanometer to micrometer range, imparting a high yield strength well in excess of 1 GPa. This heterogeneity results from this alloy's low stacking fault energy, which facilitates corner twins in recrystallization and stores deformation twins and stacking faults during tensile straining. After yielding, the elastoplastic transition through load transfer and strain partitioning among grains of different sizes leads to an upturn of the strain hardening rate, and, upon further tensile straining at room temperature, corner twins evolve into nanograins. This dynamically reinforced HGS leads to a sustainable strain hardening rate, a record-wide hysteresis loop in load-unload-reload stress-strain curve and hence high back stresses, and, consequently, a uniform tensile strain of 22%. As such, this HGS achieves, in a singlephase FCC alloy, a strength-ductility combination that would normally require heterogeneous microstructures such as in dual-phase steels.
分类号一类
URL标识查看原文
WOS关键词TRANSFORMATION-INDUCED PLASTICITY ; SOLID-SOLUTION ALLOYS ; MECHANICAL-PROPERTIES ; GRADIENT STRUCTURE ; TENSILE PROPERTIES ; STAINLESS-STEEL ; DEFORMATION-BEHAVIOR ; NANOSTRUCTURED METAL ; TWIP STEEL ; EVOLUTION
WOS研究方向Multidisciplinary Sciences
语种英语
WOS记录号WOS:000438050900050
资助机构National Key R&D Program of China [2017YFA0204402] ; Strategic Priority Research Program of the Chinese Academy of Sciences [XDB22040503] ; Natural Science Foundation of China [11572328, 11790293, 11472286] ; US Department of Energy, Division of Materials Sciences and Engineering [DE-FG02-16ER46056]
源URL[http://dspace.imech.ac.cn/handle/311007/77831]  
专题力学研究所_非线性力学国家重点实验室
作者单位1.Chinese Acad Sci, Inst Mech, State Key Lab Nonlinear Mech, Beijing 100190, Peoples R China
2.Univ Chinese Acad Sci, Sch Engn Sci, Beijing 100049, Peoples R China
3.Johns Hopkins Univ, Dept Mat Sci & Engn, Baltimore, MD 21218 USA
推荐引用方式
GB/T 7714		 Yang MX,Yan DS,Yuan FP,et al. Dynamically reinforced heterogeneous grain structure prolongs ductility in a medium-entropy alloy with gigapascal yield strength[J]. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA,2018,115(28):7224-7229.
APA 杨沐鑫,严定舜,袁福平,姜萍,Ma E,&武晓雷.(2018).Dynamically reinforced heterogeneous grain structure prolongs ductility in a medium-entropy alloy with gigapascal yield strength.PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA,115(28),7224-7229.
MLA 杨沐鑫,et al."Dynamically reinforced heterogeneous grain structure prolongs ductility in a medium-entropy alloy with gigapascal yield strength".PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 115.28(2018):7224-7229.

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来源：力学研究所

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