Dislocation structures below a nano-indent of the CoCrNi medium-entropy alloy

IA Alhafez and CJ Ruestes and ST Zhao and AM Minor and HM Urbassek, MATERIALS LETTERS, 283, 128821 (2021).

DOI: 10.1016/j.matlet.2020.128821

Using diffraction-contrast scanning transmission electron microscopy and molecular dynamics simulation, we study nanoindentation of a CoCrNi medium-entropy alloy. We find that the dislocation field produced can be separated into a zone of strongly entangled dislocations in the vicinity of the indenter and a zone of individual emitted loops that penetrate far from the indenter into the material interior. Comparing results obtained at 77 K and at 300 K, we observe at low temperature an increased hardness of the CoCrNi medium-entropy alloy, a higher dislocation density at the pit boundary, and more fragmented twinning boundaries indicating less twin growth. (C) 2020 Elsevier B.V. All rights reserved.

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