Annealing effect on plastic flow in nanocrystalline CoCrFeMnNi high-entropy alloy: A nanomechanical analysis

Lee, Dong-Hyun and Lee, Jung-A and Zhao, Yakai and Lu, Zhaoping and Suh, Jin-Yoo and Kim, Ju-Young and Ramamurty, Upadrasta and Kawasaki, Megumi and Langdon, Terence G and Jang, Jae-il (2017) Annealing effect on plastic flow in nanocrystalline CoCrFeMnNi high-entropy alloy: A nanomechanical analysis. In: ACTA MATERIALIA, 140 . pp. 443-451.

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Abstract

The influence of annealing on the constitutive stress-strain response of nanocrystalline (nc) CoCrFeMnNi high-entropy alloy (HEA) was investigated through a series of nanoindentation experiments using five different three-sided pyramidal indenters. The nc HEA, produced by high-pressure torsion (HPT), was subjected to annealing at 450 degrees C for 1 and 10 h. Microstructural analysis using transmission electron microscopy (TEM) showed that three different nano-scale precipitates (NiMn-, FeCo-, and Co-rich phases) form in the primary single-phase matrix of nc HEA after annealing. The strain-dependent plastic flow response of nc HEA pre- and post-annealing was estimated using the indentation strain and constraint factor, revealing a significant strain softening in nc HEA, which becomes pronounced after annealing. TEM analysis of the deformed material underneath the indenter suggests that the plastic deformation aids in the dissolution of the annealing-induced intermetallic precipitates, which could be the mechanism for the pronounced softening. The dissolution mechanism was rationalized by the destabilization of precipitates during plastic deformation due to the increase in interface energy. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Item Type:	Journal Article
Publication:	ACTA MATERIALIA
Additional Information:	Copy right for this article belongs to the PERGAMON-ELSEVIER SCIENCE LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	17 Nov 2017 05:29
Last Modified:	17 Nov 2017 05:29
URI:	http://eprints.iisc.ac.in/id/eprint/58258

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