History-independent cyclic response of nanotwinned metals

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	History-independent cyclic response of nanotwinned metals
	Pan, Qingsong; Zhou, Haofei; Lu, Qiuhong; Gao, Huajian; Lu, Lei; Lu, L (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Liaoning, Peoples R China.; Gao, HJ (reprint author), Brown Univ, Sch Engn, Providence, RI 02912 USA.
刊名	NATURE PUBLISHING GROUP
	2017-11-09
卷号	551 期号:7679 页码:214-+
ISSN号	0028-0836
英文摘要	Nearly 90 per cent of service failures of metallic components and structures are caused by fatigue at cyclic stress amplitudes much lower than the tensile strength of the materials involved(1). Metals typically suffer from large amounts of cumulative, irreversible damage to microstructure during cyclic deformation, leading to cyclic responses that are unstable (hardening or softening)(2-4) and history-dependent(5-8). Existing rules for fatigue life prediction, such as the linear cumulative damage rule(1,9), cannot account for the effect of loading history, and engineering components are often loaded by complex cyclic stresses with variable amplitudes, mean values and frequencies(10,11), such as aircraft wings in turbulent air. It is therefore usually extremely challenging to predict cyclic behaviour and fatigue life under a realistic load spectrum(1,11). Here, through both atomistic simulations and variable-strain-amplitude cyclic loading experiments at stress amplitudes lower than the tensile strength of the metal, we report a history-independent and stable cyclic response in bulk copper samples that contain highly oriented nanoscale twins. We demonstrate that this unusual cyclic behaviour is governed by a type of correlated 'necklace' dislocation consisting of multiple short component dislocations in adjacent twins, connected like the links of a necklace. Such dislocations are formed in the highly oriented nanotwinned structure under cyclic loading and help to maintain the stability of twin boundaries and the reversible damage, provided that the nanotwins are tilted within about 15 degrees of the loading axis. This cyclic deformation mechanism is distinct from the conventional strain localizing mechanisms associated with irreversible microstructural damage in single-crystal(12,13), coarsegrained(1,14), ultrafine-grained and nanograined metals(4,15,16).; Nearly 90 per cent of service failures of metallic components and structures are caused by fatigue at cyclic stress amplitudes much lower than the tensile strength of the materials involved(1). Metals typically suffer from large amounts of cumulative, irreversible damage to microstructure during cyclic deformation, leading to cyclic responses that are unstable (hardening or softening)(2-4) and history-dependent(5-8). Existing rules for fatigue life prediction, such as the linear cumulative damage rule(1,9), cannot account for the effect of loading history, and engineering components are often loaded by complex cyclic stresses with variable amplitudes, mean values and frequencies(10,11), such as aircraft wings in turbulent air. It is therefore usually extremely challenging to predict cyclic behaviour and fatigue life under a realistic load spectrum(1,11). Here, through both atomistic simulations and variable-strain-amplitude cyclic loading experiments at stress amplitudes lower than the tensile strength of the metal, we report a history-independent and stable cyclic response in bulk copper samples that contain highly oriented nanoscale twins. We demonstrate that this unusual cyclic behaviour is governed by a type of correlated 'necklace' dislocation consisting of multiple short component dislocations in adjacent twins, connected like the links of a necklace. Such dislocations are formed in the highly oriented nanotwinned structure under cyclic loading and help to maintain the stability of twin boundaries and the reversible damage, provided that the nanotwins are tilted within about 15 degrees of the loading axis. This cyclic deformation mechanism is distinct from the conventional strain localizing mechanisms associated with irreversible microstructural damage in single-crystal(12,13), coarsegrained(1,14), ultrafine-grained and nanograined metals(4,15,16).
学科主题	Multidisciplinary Sciences
语种	英语
资助机构	National Natural Science Foundation of China (NSFC) [51371171, 51471172, U1608257]; Key Research Program of Frontier Science, Chinese Academy of Sciences; US National Science Foundation [DMR-1709318]; Extreme Science and Engineering Discovery Environment (XSEDE) [MS090046]; NSFC [51420105001]
公开日期	2018-01-10
内容类型	期刊论文
源URL	[http://ir.imr.ac.cn/handle/321006/78979]
专题	金属研究所_中国科学院金属研究所
通讯作者	Lu, L (reprint author), Chinese Acad Sci, Inst Met Res, Shenyang Natl Lab Mat Sci, Shenyang 110016, Liaoning, Peoples R China.; Gao, HJ (reprint author), Brown Univ, Sch Engn, Providence, RI 02912 USA.
推荐引用方式 GB/T 7714	Pan, Qingsong,Zhou, Haofei,Lu, Qiuhong,et al. History-independent cyclic response of nanotwinned metals[J]. NATURE PUBLISHING GROUP,2017,551(7679):214-+.
APA	Pan, Qingsong.,Zhou, Haofei.,Lu, Qiuhong.,Gao, Huajian.,Lu, Lei.,...&Gao, HJ .(2017).History-independent cyclic response of nanotwinned metals.NATURE PUBLISHING GROUP,551(7679),214-+.
MLA	Pan, Qingsong,et al."History-independent cyclic response of nanotwinned metals".NATURE PUBLISHING GROUP 551.7679(2017):214-+.