PSI - Issue 71

Available online at www.sciencedirect.com

ScienceDirect

Procedia Structural Integrity 71 (2025) 172–179

5 th International Structural Integrity Conference & Exhibition (SICE 2024) Superplasticity at High Strain Rates: Exploring the Potential of a New Eutectic High-Entropy Alloy S. R. Reddy* Department of Metallurgical & Materials Engineering, VNIT Nagpur, Nagpur, Maharashtra 440010, India. Abstract This study investigates the high-temperature deformation behavior of a fine-grained AlCoCrFeNi 2.1 eutectic high-entropy alloy (EHEA). AlCoCrFeNi 2.1 EHEA exhibited remarkable superplasticity at high strain rates, achieving ~960% elongation at 900 °C and 10 -1 s -1 . Optimal superplasticity is observed at a strain rate sensitivity (m) of ~0.5, with transitions to non-superplastic behavior both at low and high strain rates. The influence of strain rate (3x10 -4 s -1 to 10 -1 s -1 ) and temperature (700 to 900 °C) on ductility and ‘ m ’ is significant with a combination of high temperature and high strain rate showing exceptional superplasticity. Grain boundary sliding appeared to be the dominant mechanism, which was facilitated by the retention of an equiaxed grain structure. Fractured samples revealed cavities of 1- 5 μm, suggesting nucleation, but growth was limited by a plasticity -driven mechanism proportional to cavity size. These findings highlight the potential of this EHEA for high-temperature applications. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SICE 2024 organizers

Keywords: High entropy alloys; Superplasticity; Grain boundary sliding; High strain rate

1. Introduction High-entropy alloys (HEA) are one of the new class of alloys on demand in recent years due to their unique properties and complex microstructures (Murty et al., 2014; Reddy et al., 2022; Yeh, 2006; Yeh et al., 2004). Among these Eutectic HEAs have garnered attention due to their mixture of soft and hard phases resulting in improved microstructure properties and workability(Bhattacharjee et al., 2018; Wani et al., 2016; Wani et al., 2016). High

* Corresponding author. Tel.: +917122802311. E-mail address: srreddy@mme.vnit.ac.in

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SICE 2024 organizers 10.1016/j.prostr.2025.08.024