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Title: Self-similar random process and chaotic behavior in serrated flow of high entropy alloys

Abstract

Here, the statistical and dynamic analyses of the serrated-flow behavior in the nanoindentation of a high-entropy alloy, Al 0.5CoCrCuFeNi, at various holding times and temperatures, are performed to reveal the hidden order associated with the seemingly-irregular intermittent flow. Two distinct types of dynamics are identified in the high-entropy alloy, which are based on the chaotic time-series, approximate entropy, fractal dimension, and Hurst exponent. The dynamic plastic behavior at both room temperature and 200 °C exhibits a positive Lyapunov exponent, suggesting that the underlying dynamics is chaotic. The fractal dimension of the indentation depth increases with the increase of temperature, and there is an inflection at the holding time of 10 s at the same temperature. A large fractal dimension suggests the concurrent nucleation of a large number of slip bands. In particular, for the indentation with the holding time of 10 s at room temperature, the slip process evolves as a self-similar random process with a weak negative correlation similar to a random walk.

Authors:
 [1];  [2];  [2];  [1];  [2];  [2];  [3];  [3];  [3];  [4];  [1]
  1. The Univ. of Tennessee, Knoxville, TN (United States)
  2. Zhengzhou Univ. (China)
  3. Univ. of Kentucky, Lexington, KY (United States)
  4. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; National Science Foundation (NSF); National Natural Science Foundation of China (NNSFC); U.S. Army Research Laboratory - U.S. Army Research Office (ARO)
OSTI Identifier:
1341016
Grant/Contract Number:
AC02-06CH11357
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; material science; mathematics and computing

Citation Formats

Chen, Shuying, Yu, Liping, Ren, Jingli, Xie, Xie, Li, Xueping, Xu, Ying, Zhao, Guangfeng, Li, Peizhen, Yang, Fuqian, Ren, Yang, and Liaw, Peter K. Self-similar random process and chaotic behavior in serrated flow of high entropy alloys. United States: N. p., 2016. Web. doi:10.1038/srep29798.
Chen, Shuying, Yu, Liping, Ren, Jingli, Xie, Xie, Li, Xueping, Xu, Ying, Zhao, Guangfeng, Li, Peizhen, Yang, Fuqian, Ren, Yang, & Liaw, Peter K. Self-similar random process and chaotic behavior in serrated flow of high entropy alloys. United States. doi:10.1038/srep29798.
Chen, Shuying, Yu, Liping, Ren, Jingli, Xie, Xie, Li, Xueping, Xu, Ying, Zhao, Guangfeng, Li, Peizhen, Yang, Fuqian, Ren, Yang, and Liaw, Peter K. Wed . "Self-similar random process and chaotic behavior in serrated flow of high entropy alloys". United States. doi:10.1038/srep29798. https://www.osti.gov/servlets/purl/1341016.
@article{osti_1341016,
title = {Self-similar random process and chaotic behavior in serrated flow of high entropy alloys},
author = {Chen, Shuying and Yu, Liping and Ren, Jingli and Xie, Xie and Li, Xueping and Xu, Ying and Zhao, Guangfeng and Li, Peizhen and Yang, Fuqian and Ren, Yang and Liaw, Peter K.},
abstractNote = {Here, the statistical and dynamic analyses of the serrated-flow behavior in the nanoindentation of a high-entropy alloy, Al0.5CoCrCuFeNi, at various holding times and temperatures, are performed to reveal the hidden order associated with the seemingly-irregular intermittent flow. Two distinct types of dynamics are identified in the high-entropy alloy, which are based on the chaotic time-series, approximate entropy, fractal dimension, and Hurst exponent. The dynamic plastic behavior at both room temperature and 200 °C exhibits a positive Lyapunov exponent, suggesting that the underlying dynamics is chaotic. The fractal dimension of the indentation depth increases with the increase of temperature, and there is an inflection at the holding time of 10 s at the same temperature. A large fractal dimension suggests the concurrent nucleation of a large number of slip bands. In particular, for the indentation with the holding time of 10 s at room temperature, the slip process evolves as a self-similar random process with a weak negative correlation similar to a random walk.},
doi = {10.1038/srep29798},
journal = {Scientific Reports},
number = ,
volume = 6,
place = {United States},
year = {Wed Jul 20 00:00:00 EDT 2016},
month = {Wed Jul 20 00:00:00 EDT 2016}
}

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  • Compression behavior of the Al 0.5CoCrCuFeNi high-entropy alloy (HEA) was studied at different temperatures from 673 K to 873 K at a low strain rate of 5 x 10 –5/s to investigate the temperature effect on the mechanical properties and serration behavior. The face-centered-cubic (fcc) structure is confirmed at the lower temperature of 673 K and 773 K, and a structure of mixed fcc and body-centered cubic (bcc) is identified at a higher temperature of 873 K after compression tests using high-energy synchrotron x-ray diffraction. As a result, by comparing the stress–strain curves at different temperatures, two opposite directions ofmore » serrations types were found, named upward serrations appearing at 673 K and 773 K and downward serrations at 873 K, which may be due to dynamic strain aging.« less
  • Compression behavior of the Al 0.5CoCrCuFeNi high-entropy alloy (HEA) was studied at different temperatures from 673 K to 873 K at a low strain rate of 5 x 10 –5/s to investigate the temperature effect on the mechanical properties and serration behavior. The face-centered-cubic (fcc) structure is confirmed at the lower temperature of 673 K and 773 K, and a structure of mixed fcc and body-centered cubic (bcc) is identified at a higher temperature of 873 K after compression tests using high-energy synchrotron x-ray diffraction. As a result, by comparing the stress–strain curves at different temperatures, two opposite directions ofmore » serrations types were found, named upward serrations appearing at 673 K and 773 K and downward serrations at 873 K, which may be due to dynamic strain aging.« less
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