title: Self-Similar Random Process and Chaotic Behavior In Serrated Flow of High Entropy Alloys.
abstract: 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.
authors.affiliation: Department of Materials Science and Engineering, The University of Tennessee, USA.
authors.forename: Shuying
authors.initials: S
authors.lastname: Chen
authors.affiliation: School of Mathematics and Statistics, Zhengzhou University, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Yu
authors.affiliation: School of Mathematics and Statistics, Zhengzhou University, China.
authors.forename: Jingli
authors.initials: J
authors.lastname: Ren
authors.affiliation: Department of Materials Science and Engineering, The University of Tennessee, USA.
authors.forename: Xie
authors.initials: X
authors.lastname: Xie
authors.affiliation: School of Mathematics and Statistics, Zhengzhou University, China.
authors.forename: Xueping
authors.initials: X
authors.lastname: Li
authors.affiliation: School of Mathematics and Statistics, Zhengzhou University, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Chemical and Materials Engineering, University of Kentucky, USA.
authors.forename: Guangfeng
authors.initials: G
authors.lastname: Zhao
authors.affiliation: Department of Chemical and Materials Engineering, University of Kentucky, USA.
authors.forename: Peizhen
authors.initials: P
authors.lastname: Li
authors.affiliation: Department of Chemical and Materials Engineering, University of Kentucky, USA.
authors.forename: Fuqian
authors.initials: F
authors.lastname: Yang
authors.affiliation: X-ray Science Division, Argonne National Laboratory, Argonne, Illinois, 60439, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Ren
authors.affiliation: Department of Materials Science and Engineering, The University of Tennessee, USA.
authors.forename: Peter K
authors.initials: PK
authors.lastname: Liaw