Comparative studies of yield strength and elastic compressibility between nanocrystalline and bulk cobalt were conducted using synchrotron x-ray diffraction under tri-axial pressure loading-unloading conditions. Relative to micron Co, nano Co exhibits higher flow stress (2.9 GPa compared with 2.1 GPa in micro Co), extra degree of strain-induced peak broadening during loading yet a better strain recoverability after unloading. These observations suggest different deformation mechanisms with intergranular strains dominated in nano Co and intragranular strains in micron Co. The determined bulk modulus for nano Co is 216 GPa, ∼17% higher than that of micron Co (185 GPa). This finding supports a generalized model of nanocrystals with pre-compressed surface layers and indicates that the grain-size induced elastic strengthening and weakening are primarily determined by the nature of internal stress (compressed vs. tensile) present in the surface layer of a nanocrystal.
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1 June 2012
Research Article|
June 01 2012
Comparative studies of yield strength and elastic compressibility between nanocrystalline and bulk cobalt
Xiaohui Yu;
Xiaohui Yu
a)
1
LANSCE Division, Los Alamos National Laboratory
, Los Alamos, New Mexico 87545, USA
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Jianzhong Zhang;
Jianzhong Zhang
1
LANSCE Division, Los Alamos National Laboratory
, Los Alamos, New Mexico 87545, USA
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Yingying Zhang;
Yingying Zhang
2
CINT, Los Alamos National Laboratory
, Los Alamos, New Mexico 87545, USA
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Liping Wang;
Liping Wang
3High Pressure Science and Engineering Center (HiPSEC) and Department of Physics and Astronomy,
University of Nevada
, Las Vegas, Nevada 89154, USA
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Yusheng Zhao
Yusheng Zhao
a)
1
LANSCE Division, Los Alamos National Laboratory
, Los Alamos, New Mexico 87545, USA
3High Pressure Science and Engineering Center (HiPSEC) and Department of Physics and Astronomy,
University of Nevada
, Las Vegas, Nevada 89154, USA
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a)
Authors to whom correspondence should be addressed. Electronic addresses: xiaohui@lanl.gov and yusheng.zhao@unlv.edu.
J. Appl. Phys. 111, 113506 (2012)
Article history
Received:
March 28 2012
Accepted:
April 30 2012
Citation
Xiaohui Yu, Jianzhong Zhang, Yingying Zhang, Liping Wang, Yusheng Zhao; Comparative studies of yield strength and elastic compressibility between nanocrystalline and bulk cobalt. J. Appl. Phys. 1 June 2012; 111 (11): 113506. https://doi.org/10.1063/1.4724338
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