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Asymmetric cyclic response of tensile pre-deformed Cu with highly oriented nanoscale twins
Pan, Qingsong; Zhou, Haofei; Lu, Qiuhong; Gao, Huajian; Lu, Lei
2019-08-15
Source PublicationACTA MATERIALIA
ISSN1359-6454
Volume175Pages:477-486
AbstractHistory-independent, stable and symmetric cyclic response has been detected in as-deposited bulk polycrystalline Cu with highly oriented nanotwins [Nature 551 (2017) 214-217]. In this study, to deepen the understanding of cyclic deformation in nanotwinned (NT) structures, small levels of tensile pre-strains were applied on NT-Cu, followed by strain-controlled symmetric tension-compression cyclic tests. Distinct from the symmetric cyclic response of as-deposited NT-Cu, the magnitude of the maximum stress in tension is much larger than that of the minimum stress in compression, indicating that the cyclic response of tensile pre-deformed NT-Cu is highly asymmetric. The degree of its cyclic asymmetry gradually decays as the number of cycles or the plastic strain amplitude is increased. The tensile pre-deformed NT-Cu recovers to its symmetric cyclic response after cyclic deformation at sufficiently large plastic strain amplitude, analogous to that detected in as-deposited NT counterparts. Molecular dynamics simulations and microstructural observations revealed that the observed asymmetric cyclic response is mainly related to the activation and movement of threading dislocations with extended misfit dislocation tails lying on the twin boundaries (TBs) during tensile pre-deformation. During cyclic deformation, threading dislocations in adjacent twin interiors tend to link their long tails with one another to form correlated necklace dislocations (CNDs) with a symmetric structure. The CNDs move back-and-forth along the twin boundaries without directional slip resistance, contributing to the transition from asymmetric to symmetric cyclic response of NT-Cu. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
KeywordNanotwin Pre-strain effect Asymmetric cyclic response Correlated necklace dislocations Fatigue mechanism
Indexed BySCI
Language英语
WOS IDWOS:000479023600043
PublisherPERGAMON-ELSEVIER SCIENCE LTD
Citation statistics
Document Type期刊论文
Identifierhttp://ir.imr.ac.cn/handle/321006/80834
Collection中国科学院金属研究所
Recommended Citation
GB/T 7714
Pan, Qingsong,Zhou, Haofei,Lu, Qiuhong,et al. Asymmetric cyclic response of tensile pre-deformed Cu with highly oriented nanoscale twins[J]. ACTA MATERIALIA,2019,175:477-486.
APA Pan, Qingsong,Zhou, Haofei,Lu, Qiuhong,Gao, Huajian,&Lu, Lei.(2019).Asymmetric cyclic response of tensile pre-deformed Cu with highly oriented nanoscale twins.ACTA MATERIALIA,175,477-486.
MLA Pan, Qingsong,et al."Asymmetric cyclic response of tensile pre-deformed Cu with highly oriented nanoscale twins".ACTA MATERIALIA 175(2019):477-486.
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