Influence of Process Parameters on Microstructure Evolution During Hot Deformation of a Eutectic High-Entropy Alloy (EHEA)

Ahmed, M. Zaid and Chadha, K. and Reddy, S. R. and Shahriari, D. and Bhattacharjee, Pinaki Prasad and Jahazi, M. (2020) Influence of Process Parameters on Microstructure Evolution During Hot Deformation of a Eutectic High-Entropy Alloy (EHEA). Metallurgical and Materials Transactions A, 51 (12). pp. 6406-6420. ISSN 1073-5623

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Abstract

High-entropy alloys (HEAs) have shown unique combinations of strength and ductility along with other properties after optimized thermomechanical processing (TMP). In this study, the hot deformation of an AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA) was studied by using a Gleeble 3800® thermomechanical simulator at 800 °C, 1000 °C and 1200 °C deformation temperature under different strain rates of 10−4, 10−2, and 1 s−1. The influence of strain rate and temperature on the evolution of the microstructure was discussed. The apparent activation energy (Q), stress exponent (n) and Zener–Holloman parameter (Z) were determined from the true stress–strain curves to develop the constitutive equation. The activation energy was determined to be 336 kJ/mol, and the stress exponent (n) was 2.5. Microstructures, characterized using electron-backscattered diffraction (EBSD), were analyzed as a function of (Z) values and interpreted in terms of solute diffusion and the interactions between dynamic softening (dynamic recovery and dynamic recrystallization) and hardening (dynamic precipitation) phenomena. It was found that the hot deformation behavior of EHEAs was controlled by pipe diffusion for the selected process parameters. The pipe diffusion coefficient of Ni increased with increasing strain rate at constant deformation temperature, whereas the lattice diffusion coefficient remained constant for all the examined strain rates. Dynamic recovery (DRV) was the dominant softening mechanism at lower temperatures irrespective of strain rates, while dynamic precipitation played a critical role in the inhibition of dynamic recrystallization (DRX) under these conditions. At higher temperatures and for all the strain rates, microstructure evolution was controlled by the DRX mechanism.

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IITH Creators:

IITH Creators	ORCiD
Reddy, S R	UNSPECIFIED
Bhattacharjee, Pinaki Prasad	http://orcid.org/0000-0002-6422-2601

Item Type:

Article

Uncontrolled Keywords:

Apparent activation energy; Dynamic recrystallization (DRX); Electron back-scattered diffraction; Evolution of the microstructure; Influence of process parameters; Micro-structure evolutions; Thermo-mechanical processing; Thermomechanical simulator; Activation energy; Aluminum alloys; Chromium alloys; Cobalt alloys; Deformation; Diffusion; Dynamic recrystallization; Dynamics; Entropy; Eutectics; High-entropy alloys; Iron alloys; Microstructure; Thermomechanical treatment

Subjects:

Materials Engineering > Materials engineering
Materials Engineering > Nanostructured materials, porous materials

Divisions:

Department of Material Science Engineering

Depositing User:

. LibTrainee 2021

Date Deposited:

25 Jun 2021 04:50

Last Modified:

25 Jun 2021 04:50

URI:

http://raiithold.iith.ac.in/id/eprint/8000