Abstract
Nanoindentation tests were performed to investigate the nano-scale plastic deformation in the Al0.5CoCrCuFeNi high entropy alloys at room temperature (RT) and 200 °C, respectively. Serrated plastic flow, manifested as discrete bursts of plasticity on the load-displacement curves, was observed for both temperatures during the loading period, and its behavior and dependence on the temperature was analyzed from both the experimental and theoretical perspectives. The application of a mean-field theory indicated that the displacement bursts exhibited a temperature-dependent power-law distribution, and the universal exponents, κ and λ, were computed to be 1.5 and 0.04, respectively. With the use of the computed universal exponents, a critical annealing temperature for the slip-avalanche size distribution was estimated to be 1120 °C. Creep occurred during the nanoindentation holding period and exhibited very large stress exponent, implying that the dislocation glide-climb is the dominant mechanism. The creep simulations with a two-layer viscoplastic model further revealed that the deformation at a higher temperature (e.g., 200 °C) featured a greater and faster-growing plastic zone underneath the indenter, implying more pronounced dislocation activities.
Original language | English |
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Pages (from-to) | 464-475 |
Number of pages | 12 |
Journal | Journal of Alloys and Compounds |
Volume | 752 |
DOIs | |
State | Published - Jul 5 2018 |
Bibliographical note
Funding Information:We are grateful for the support of the Department of Energy ( DOE ) Office of Fossil Energy, National Energy Technology Laboratory ( NETL ) ( DE-FE0008855 , DE-FE-0024054 , and DE-FE-0011194 ) and the National Science Foundation ( DMR-1611180 ), with Drs. J. Mullen, V. Cedro, R. Dunst, S. Markovich, and D. Farkas as program managers. P.K.L. very much appreciates the support from the U.S. Army Office Project ( W911NF-13-1-0438 ) with the program manager, Drs. M. P. Bakas, S. N. Mathaudhu, and D. M. Stepp. P. K. L. would like to acknowledge the financial support of the Center for Materials Processing ( CMP ), at the University of Tennessee, with the director of Dr. Claudia J. Rawn. J.W.Q. would like to acknowledge the financial support of the Youth Natural Science Foundation of the Shanxi Province, China (No. 2015021005 ). P. K. L. is also pleased to acknowledge the financial support by the Ministry of Science and Technology of Taiwan , under Grant No. MOST 105-2221-E-007-017-MY3 , and the Department of Materials Science and Engineering, National Tsing Hua University, Taiwan .
Funding Information:
We are grateful for the support of the Department of Energy (DOE) Office of Fossil Energy, National Energy Technology Laboratory (NETL) (DE-FE0008855, DE-FE-0024054, and DE-FE-0011194) and the National Science Foundation (DMR-1611180), with Drs. J. Mullen, V. Cedro, R. Dunst, S. Markovich, and D. Farkas as program managers. P.K.L. very much appreciates the support from the U.S. Army Office Project (W911NF-13-1-0438) with the program manager, Drs. M. P. Bakas, S. N. Mathaudhu, and D. M. Stepp. P. K. L. would like to acknowledge the financial support of the Center for Materials Processing (CMP), at the University of Tennessee, with the director of Dr. Claudia J. Rawn. J.W.Q. would like to acknowledge the financial support of the Youth Natural Science Foundation of the Shanxi Province, China (No. 2015021005). P. K. L. is also pleased to acknowledge the financial support by the Ministry of Science and Technology of Taiwan, under Grant No. MOST 105-2221-E-007-017-MY3, and the Department of Materials Science and Engineering, National Tsing Hua University, Taiwan.
Publisher Copyright:
© 2018 Elsevier B.V.
Keywords
- Creep mechanism
- Finite element modeling
- Nanoindentation
- Serrated flow
- Serration statistics
ASJC Scopus subject areas
- Mechanics of Materials
- Mechanical Engineering
- Metals and Alloys
- Materials Chemistry