Deformation, structural changes and damage evolution in nanotwinned copper under repeated frictional contact sliding

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	Deformation, structural changes and damage evolution in nanotwinned copper under repeated frictional contact sliding
	A. Singh; M. Dao; L. Lu; S. Suresh
	2011
发表期刊	Acta Materialia
ISSN	1359-6454
卷号	59 期号:19 页码:7311-7324
摘要	Nanotwinned metals have the potential for use as structural materials by virtue of having a combination of high strength as well as reasonable ductility and damage tolerance. In the current study, the tribological response of nanotwinned copper has been characterized under conditions of repeated frictional sliding contact with a conical tip diamond indenter. Pure ultrafine-grained copper specimens of fixed grain size (similar to 450 nm), but with three different structural conditions involving relatively high, medium and negligible concentrations of nanotwins, were studied. The effects of twin density and number of repetitions of sliding cycles on the evolution of friction and material pile-up around the diamond indenter were studied quantitatively by depth-sensing instrumented frictional sliding. Cross-sectional focused ion beam and scanning electron microscopy observations were used to systematically monitor deformation-induced structural changes as a function of the number of passes of repeated frictional sliding. Nanoindentation tests at the base of the sliding tracks coupled with large-deformation finite-element modeling simulations were used to assess local gradients in mechanical properties and deformation around the indenter track. The results indicate that friction evolution as well as local mechanical response is more strongly influenced by local structure evolution during repeated sliding than by the initial structure. An increase in twin density is found to result in smaller pile-up height and friction coefficient. Compared to the low-density nanotwinned metal, high-density nanotwinned copper showed significantly higher resistance to surface damage and structural changes, after the initial scratch. However with an increase in the number of sliding passes, the friction coefficient and rate of increase of pile up for all specimens acquire a steady value which does not change significantly in subsequent scratch passes. The frictional sliding experiments also lead to the striking result that copper specimens with both a high and low density of nanotwins eventually converge to a similar microstructure underneath the indenter after repeated tribological deformation. This trend strongly mirrors the well-known steady-state response of mierocrystalline copper subjected to uniaxial cyclic loading. General perspectives on contact fatigue response of nanotwinned copper are developed on the basis of these new findings. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
部门归属	[singh, a.; dao, m.; suresh, s.] mit, dept mat sci & engn, cambridge, ma 02139 usa. [lu, l.] chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, peoples r china.;dao, m (reprint author), mit, dept mat sci & engn, cambridge, ma 02139 usa;mingdao@mit.edu
关键词	Nanoscale Twins Contact Fatigue Wear Resistance Microstructure Evolution Nanocrystalline Copper Strain-rate Sensitivity Grain-refinement Nanocrystalline Metals Dislocation-structures Nanostructured Metals Mechanical-properties Plastic-deformation Stainless-steel Fcc Metals Sn Bronze
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WOS记录号	WOS:000296405200018
引用统计	被引频次：42[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.imr.ac.cn/handle/321006/30664
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	A. Singh,M. Dao,L. Lu,et al. Deformation, structural changes and damage evolution in nanotwinned copper under repeated frictional contact sliding[J]. Acta Materialia,2011,59(19):7311-7324.
APA	A. Singh,M. Dao,L. Lu,&S. Suresh.(2011).Deformation, structural changes and damage evolution in nanotwinned copper under repeated frictional contact sliding.Acta Materialia,59(19),7311-7324.
MLA	A. Singh,et al."Deformation, structural changes and damage evolution in nanotwinned copper under repeated frictional contact sliding".Acta Materialia 59.19(2011):7311-7324.