Unraveling the origin of extra strengthening in gradient nanotwinned metals
Materials containing heterogeneous nanostructures hold great promise for achieving superior mechanical properties. However, the strengthening effect due to plastically inhomogeneous deformation in heterogeneous nanostructures has not been clearly understood. Here, we investigate a prototypical heter...
Saved in:
Main Authors: | , , , , , , |
---|---|
Other Authors: | |
Format: | Article |
Language: | English |
Published: |
2022
|
Subjects: | |
Online Access: | https://hdl.handle.net/10356/161787 |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Institution: | Nanyang Technological University |
Language: | English |
id |
sg-ntu-dr.10356-161787 |
---|---|
record_format |
dspace |
spelling |
sg-ntu-dr.10356-1617872022-09-20T04:21:06Z Unraveling the origin of extra strengthening in gradient nanotwinned metals Cheng, Zhao Bu, Linfeng Zhang, Yin Wu, HengAn Zhu, Ting Gao, Huajian Lu, Lei School of Mechanical and Aerospace Engineering Institute of High Performance Computing, Agency for Science, (A*STAR) Engineering::Mechanical engineering Gradient Nanotwinned Metal Extra Strengthening Materials containing heterogeneous nanostructures hold great promise for achieving superior mechanical properties. However, the strengthening effect due to plastically inhomogeneous deformation in heterogeneous nanostructures has not been clearly understood. Here, we investigate a prototypical heterogeneous nanostructured material of gradient nanotwinned (GNT) Cu to unravel the origin of its extra strength arising from gradient nanotwin structures relative to uniform nanotwin counterparts. We measure the back and effective stresses of GNT Cu with different nanotwin thickness gradients and compare them with those of homogeneous nanotwinned Cu with different uniform nanotwin thicknesses. We find that the extra strength of GNT Cu is caused predominantly by the extra back stress resulting from nanotwin thickness gradient, while the effective stress is almost independent of the gradient structures. The combined experiment and strain gradient plasticity modeling show that an increasing structural gradient in GNT Cu produces an increasing plastic strain gradient, thereby raising the extra back stress. The plastic strain gradient is accommodated by the accumulation of geometrically necessary dislocations inside an unusual type of heterogeneous dislocation structure in the form of bundles of concentrated dislocations. Such a heterogeneous dislocation structure produces microscale internal stresses leading to the extra back stress in GNT Cu. Altogether, this work establishes a fundamental connection between the gradient structure and extra strength in GNT Cu through the mechanistic linkages of plastic strain gradient, heterogeneous dislocation structure, microscale internal stress, and extra back stress. Broadly, this work exemplifies a general approach to unraveling the strengthening mechanisms in heterogeneous nanostructured materials. Agency for Science, Technology and Research (A*STAR) Nanyang Technological University Published version L.L. acknowledges support from the National Natural Science Foundation of China (Grants 51931010 and 92163202), the Key Research Program of Frontier Science and International Partnership Program (Grant GJHZ2029), the Chinese Academy of Sciences, and the LiaoNing Revitalization Talents Program (Grant XLYC1802026). Z.C. acknowledges support from the National Natural Science Foundation of China (Grant 52001312) and the China Postdoctoral Science Foundation (Grants BX20190336 and 2019M661150). H.G. acknowledges a research startup grant (002479-00001) from Nanyang Technological University and the Agency for Science, Technology and Research (A*STAR) in Singapore. 2022-09-20T04:21:06Z 2022-09-20T04:21:06Z 2022 Journal Article Cheng, Z., Bu, L., Zhang, Y., Wu, H., Zhu, T., Gao, H. & Lu, L. (2022). Unraveling the origin of extra strengthening in gradient nanotwinned metals. Proceedings of the National Academy of Sciences of the United States of America, 119(3). https://dx.doi.org/10.1073/pnas.2116808119 0027-8424 https://hdl.handle.net/10356/161787 10.1073/pnas.2116808119 35012985 2-s2.0-85123078266 3 119 en Proceedings of the National Academy of Sciences of the United States of America © The Authors. This article is distributed under Creative Commons Attribution-NonCommercialNoDerivatives License 4.0 (CC BY-NC-ND). application/pdf |
institution |
Nanyang Technological University |
building |
NTU Library |
continent |
Asia |
country |
Singapore Singapore |
content_provider |
NTU Library |
collection |
DR-NTU |
language |
English |
topic |
Engineering::Mechanical engineering Gradient Nanotwinned Metal Extra Strengthening |
spellingShingle |
Engineering::Mechanical engineering Gradient Nanotwinned Metal Extra Strengthening Cheng, Zhao Bu, Linfeng Zhang, Yin Wu, HengAn Zhu, Ting Gao, Huajian Lu, Lei Unraveling the origin of extra strengthening in gradient nanotwinned metals |
description |
Materials containing heterogeneous nanostructures hold great promise for achieving superior mechanical properties. However, the strengthening effect due to plastically inhomogeneous deformation in heterogeneous nanostructures has not been clearly understood. Here, we investigate a prototypical heterogeneous nanostructured material of gradient nanotwinned (GNT) Cu to unravel the origin of its extra strength arising from gradient nanotwin structures relative to uniform nanotwin counterparts. We measure the back and effective stresses of GNT Cu with different nanotwin thickness gradients and compare them with those of homogeneous nanotwinned Cu with different uniform nanotwin thicknesses. We find that the extra strength of GNT Cu is caused predominantly by the extra back stress resulting from nanotwin thickness gradient, while the effective stress is almost independent of the gradient structures. The combined experiment and strain gradient plasticity modeling show that an increasing structural gradient in GNT Cu produces an increasing plastic strain gradient, thereby raising the extra back stress. The plastic strain gradient is accommodated by the accumulation of geometrically necessary dislocations inside an unusual type of heterogeneous dislocation structure in the form of bundles of concentrated dislocations. Such a heterogeneous dislocation structure produces microscale internal stresses leading to the extra back stress in GNT Cu. Altogether, this work establishes a fundamental connection between the gradient structure and extra strength in GNT Cu through the mechanistic linkages of plastic strain gradient, heterogeneous dislocation structure, microscale internal stress, and extra back stress. Broadly, this work exemplifies a general approach to unraveling the strengthening mechanisms in heterogeneous nanostructured materials. |
author2 |
School of Mechanical and Aerospace Engineering |
author_facet |
School of Mechanical and Aerospace Engineering Cheng, Zhao Bu, Linfeng Zhang, Yin Wu, HengAn Zhu, Ting Gao, Huajian Lu, Lei |
format |
Article |
author |
Cheng, Zhao Bu, Linfeng Zhang, Yin Wu, HengAn Zhu, Ting Gao, Huajian Lu, Lei |
author_sort |
Cheng, Zhao |
title |
Unraveling the origin of extra strengthening in gradient nanotwinned metals |
title_short |
Unraveling the origin of extra strengthening in gradient nanotwinned metals |
title_full |
Unraveling the origin of extra strengthening in gradient nanotwinned metals |
title_fullStr |
Unraveling the origin of extra strengthening in gradient nanotwinned metals |
title_full_unstemmed |
Unraveling the origin of extra strengthening in gradient nanotwinned metals |
title_sort |
unraveling the origin of extra strengthening in gradient nanotwinned metals |
publishDate |
2022 |
url |
https://hdl.handle.net/10356/161787 |
_version_ |
1745574648676876288 |