On strain hardening mechanism in gradient nanostructures

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	On strain hardening mechanism in gradient nanostructures
	Li JJ; Weng GJ; Chen SH(陈少华); Wu XL(武晓雷)
刊名	INTERNATIONAL JOURNAL OF PLASTICITY
	2017
通讯作者邮箱	jianjunli.mech@hotmail.com
卷号	88 页码:89-107
关键词	Ductility Dislocations Constitutive behavior Inhomogeneous material Analytic functions
ISSN号	0749-6419
通讯作者	Li, JJ (reprint author), Northwestern Polytech Univ, Sch Mech Civil Engn & Architecture, Dept Engn Mech, Xian 710129, Shaanxi, Peoples R China.
产权排序	[Li, Jianjun] Northwestern Polytech Univ, Sch Mech Civil Engn & Architecture, Dept Engn Mech, Xian 710129, Shaanxi, Peoples R China; [Li, Jianjun] Max Planck Inst Eisenforsch GmbH, Dept Microstruct Phys & Alloy Design, D-40237 Dusseldorf, Germany; [Weng, G. J.] Rutgers State Univ, Dept Mech & Aerosp Engn, New Brunswick, NJ 08903 USA; [Chen, Shaohua] Beijing Inst Technol, Inst Adv Struct Technol, Beijing 100081, Peoples R China; [Wu, Xiaolei] Chinese Acad Sci, Inst Mech, State Key Lab Nonlinear Mech, Beijing 100190, Peoples R China
中文摘要	Experiments have shown that a gradient design, in which grain size spans over four orders of magnitude, can make strong nanomaterials ductile. The enhanced ductility is attributed to the considerable strain hardening capability obtained in the gradient metals. A non-uniform deformation on the lateral sample surface is also observed. This might inject geometrically necessary dislocations (GNDs) into the sample. However, no direct evidence has been provided. Therefore the issues remain: why can the gradient structure generate high strain hardening, and how does it reconcile the strength-ductility synergy of gradient nanostructures? Here for the first time we quantitatively investigate the strain hardening of a gradient interstitial-free steel by developing a dislocation density-based continuum plasticity model, in which the interaction of the component layers in the gradient structure is represented by incorporating GNDs and back stress. It is demonstrated that both the surface non-uniform deformation and the strain-hardening rate up-turn can be quantitatively well predicted. The results also show that the strain hardening rate of the gradient sample can reach as high as that of the coarse-grained counterpart. A strength-ductility map is then plotted, which clearly show that the gradient samples perform much more superior to their homogeneous counterparts in strength-ductility synergy. The predicted map has been verified by a series of experimental data. A detailed analysis on GNDs distribution and back stress evolution at the end further substantiates our view that the good strain hardening capability results from the generation of abundant GNDs by the surface non-uniform deformation into the nano-grained layers of the gradient sample. (C) 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
分类号	一类
类目[WOS]	Engineering, Mechanical ; Materials Science, Multidisciplinary ; Mechanics
研究领域[WOS]	Engineering ; Materials Science ; Mechanics
关键词[WOS]	Ductility ; Dislocations ; Constitutive behavior ; Inhomogeneous material ; Analytic functions
收录类别	SCI ; EI
原文出处	http://dx.doi.org/10.1016/j.ijplas.2016.10.003
语种	英语
WOS记录号	WOS:000389105300005
内容类型	期刊论文
源URL	[http://dspace.imech.ac.cn/handle/311007/59943]
专题	力学研究所_非线性力学国家重点实验室
推荐引用方式 GB/T 7714	Li JJ,Weng GJ,Chen SH,et al. On strain hardening mechanism in gradient nanostructures[J]. INTERNATIONAL JOURNAL OF PLASTICITY,2017,88:89-107.
APA	Li JJ,Weng GJ,陈少华,&武晓雷.(2017).On strain hardening mechanism in gradient nanostructures.INTERNATIONAL JOURNAL OF PLASTICITY,88,89-107.
MLA	Li JJ,et al."On strain hardening mechanism in gradient nanostructures".INTERNATIONAL JOURNAL OF PLASTICITY 88(2017):89-107.