Nanoscale serration and creep characteristics of Al0.5CoCrCuFeNi high-entropy alloys

Shuying Chen, Weidong Li, Xie Xie, Jamieson Brechtl, Bilin Chen, Peizhen Li, Guangfeng Zhao, Fuqian Yang, Junwei Qiao, Karin A. Dahmen, Peter K. Liaw

Research output: Contribution to journalArticlepeer-review

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 languageEnglish (US)
Pages (from-to)464-475
Number of pages12
JournalJournal of Alloys and Compounds
Volume752
DOIs
StatePublished - Jul 5 2018

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

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