Microstructure and mechanical properties at different length scales and strain rates of nanocrystalline tantalum produced by high-pressure torsion

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	Microstructure and mechanical properties at different length scales and strain rates of nanocrystalline tantalum produced by high-pressure torsion
	Wei Q; Pan ZL; Wu XL(武晓雷); Schuster BE; Kecskes LJ; Valiev RZ
刊名	Acta Materialia
	2011
通讯作者邮箱	qwei@uncc.edu
卷号	59 期号:6 页码:2423-2436
关键词	Nanocrystalline Tantalum Microstructure Mechanical Properties Adiabatic Shear Band Centered-Cubic Metals Severe Plastic-Deformation Nonequilibrium Grain-Boundaries Hall-Petch Behavior Tensile Behavior Rate Sensitivity Ultrafine Grain Shear Bands Uniaxial Compression Screw Dislocations
ISSN号	1359-6454
通讯作者	Wei, Q (reprint author), Univ N Carolina, Dept Mech Engn & Engn Sci, 9201 Univ City Blvd, Charlotte, NC 28223 USA
产权排序	[Wei, Q; Pan, ZL] Univ N Carolina, Dept Mech Engn & Engn Sci, Charlotte, NC 28223 USA; [Wu, XL] Chinese Acad Sci, Inst Mech, State Key Lab Non Linear Mech, Beijing 100190, Peoples R China; [Schuster, BE; Kecskes, LJ] USA, Res Lab, Aberdeen, MD 21005 USA; [Valiev, RZ] Ufa State Aviat Technol Univ, Inst Phys Adv Mat, Ufa 450000, Russia
合作状况	国际
中文摘要	Fully dense, nanocrystalline tantalum (average grain size as small as similar to 40 nm) has been processed for the first time by high-pressure torsion. High-resolution transmission electron microscopy reveals non-equilibrium grain boundaries and grains decorated with high-density dislocations. Microhardness measurements and instrumented nanoindentation experiments indicate that the mechanical property is quite uniform except for the central area of the disks. Nanoindentation experiments at different strain rates suggest that the strain rate sensitivity of nanocrystalline tantalum is increased compared to the coarse- and ultrafine-grained counterparts and is accompanied by an activation energy of the order of a few similar to b(3) (b is the magnitude of the dislocation Burgers vector), implying a shift in the plastic deformation mechanism from the screw dislocation dominated regime. We thus infer the plastic deformation mechanisms of nanocrystalline body-centered cubic (bcc) and face-centered cubic metals converge. To examine the stress strain behavior, we have used microcompression to measure the compressive stress strain curves on microscale pillars fabricated by focused ion beam technique. Yield strength as high as 1.6 GPa has been observed. High-strain rate behavior has been investigated using a miniature Kolsky bar system. We have found that at high-strain rates the nanocrystalline tantalum specimens exhibit adiabatic shear banding, a dynamic plastic deformation mode common to many ultrafine-grained and all nanocrystalline bcc metals. (C) 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
学科主题	Materials Science; Metallurgy & Metallurgical Engineering
分类号	一类
类目[WOS]	Materials Science, Multidisciplinary ; Metallurgy & Metallurgical Engineering
研究领域[WOS]	Materials Science ; Metallurgy & Metallurgical Engineering
关键词[WOS]	CENTERED-CUBIC METALS ; SEVERE PLASTIC-DEFORMATION ; NONEQUILIBRIUM GRAIN-BOUNDARIES ; HALL-PETCH BEHAVIOR ; TENSILE BEHAVIOR ; RATE SENSITIVITY ; ULTRAFINE GRAIN ; SHEAR BANDS ; UNIAXIAL COMPRESSION ; SCREW DISLOCATIONS
收录类别	SCI ; EI
资助信息	This work was supported by US Army Research Laboratory under Contract # W911QX-06-C-0124. The authors would like to thank Mr. W.H. Yin for assistance in some experiments. They are also indebted to Drs. Z.G. Xu and S. Yarmolenko at NC A&T State University for assistance with microhardness, nanoindentation and XRD measurement. X.L.W. acknowledges the support of NSFC Grant Nos. 11021262, 11072243, and 973 Project Grants Nos. 2010CB631004 and 2009CB623700.
原文出处	http://dx.doi.org/10.1016/j.actamat.2010.12.042
语种	英语
WOS记录号	WOS:000288568500017
公开日期	2012-04-01
内容类型	期刊论文
源URL	[http://dspace.imech.ac.cn/handle/311007/44940]
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	Wei Q,Pan ZL,Wu XL,et al. Microstructure and mechanical properties at different length scales and strain rates of nanocrystalline tantalum produced by high-pressure torsion[J]. Acta Materialia,2011,59(6):2423-2436.
APA	Wei Q,Pan ZL,武晓雷,Schuster BE,Kecskes LJ,&Valiev RZ.(2011).Microstructure and mechanical properties at different length scales and strain rates of nanocrystalline tantalum produced by high-pressure torsion.Acta Materialia,59(6),2423-2436.
MLA	Wei Q,et al."Microstructure and mechanical properties at different length scales and strain rates of nanocrystalline tantalum produced by high-pressure torsion".Acta Materialia 59.6(2011):2423-2436.