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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.
2017-11-09
Source PublicationNATURE PUBLISHING GROUP
ISSN0028-0836
Volume551Issue:7679Pages:214-+
AbstractNearly 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).
description.department[pan, qingsong ; lu, qiuhong ; lu, lei] chinese acad sci, inst met res, shenyang natl lab mat sci, shenyang 110016, liaoning, peoples r china ; [zhou, haofei ; gao, huajian] brown univ, sch engn, providence, ri 02912 usa
Subject AreaMultidisciplinary Sciences
Funding OrganizationNational 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]
Indexed BySCI
Language英语
Document Type期刊论文
Identifierhttp://ir.imr.ac.cn/handle/321006/78979
Collection中国科学院金属研究所
Corresponding AuthorLu, 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.
Recommended Citation
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-+.
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