Title
Effect of solid-solution strengthening on deformation mechanisms and strain hardening in medium-entropy V1-xCrxCoNi alloys
Author
Chung, Hyun (Korea University)
Kim, Dae Woong (Pohang University of Science and Technology)
Cho, Woo Jin (Seoul National University)
Han, Heung Nam (Seoul National University)
Ikeda, Yuji (University of Stuttgart; Max-Planck-Institut für Eisenforschung)
Ishibashi, Shoji (Max-Planck-Institut für Eisenforschung; National Institute of Advanced Industrial Science and Technology (AIST))
Körmann, F.H.W. (TU Delft Team Marcel Sluiter; Max-Planck-Institut für Eisenforschung) 
Sohn, Seok Su (Korea University)
Date
2022
Abstract
High- and medium-entropy alloys (HEAs and MEAs) possess high solid-solution strength. Numerous investigations have been conducted on its impact on yield strength, however, there are limited reports regarding the relation between solid-solution strengthening and strain-hardening rate. In addition, no attempt has been made to account for the dislocation-mediated plasticity; most works focused on twinning- or transformation-induced plasticity (TWIP or TRIP). In this work we reveal the role of solid-solution strengthening on the strain-hardening rate via systematically investigating evolutions of deformation structures by controlling the Cr/V ratio in prototypical V1-xCrxCoNi alloys. Comparing the TWIP of CrCoNi with the dislocation slip of V0.4Cr0.6CoNi, the hardening rate of CrCoNi was superior to slip-band refinements of V0.4Cr0.6CoNi due to the dynamic Hall-Petch effect. However, as V content increased further to V0.7Cr0.3CoNi and VCoNi, their rate of slip-band refinement in V0.7Cr0.3CoNi and VCoNi with high solid-solution strength surpassed that of CrCoNi. Although it is generally accepted in conventional alloys that deformation twinning results in a higher strain-hardening rate than dislocation-mediated plasticity, we observed that the latter can be predominant in the former under an activated huge solid-solution strengthening effect. The high solid-solution strength lowered the cross-slip activation and consequently retarded the dislocation rearrangement rate, i.e., the dynamic recovery. This delay in the hardening rate decrease, therefore, increased the strain-hardening rate, results in an overall higher strain-hardening rate of V-rich alloys.
Subject
Medium-entropy alloy
Solid-solution strength
Stacking fault energy
Strain-hardening rate
Tensile property
To reference this document use:
http://resolver.tudelft.nl/uuid:74104173-86fd-4498-9683-836b11818b95
DOI
https://doi.org/10.1016/j.jmst.2021.07.042
Embargo date
2022-04-30
ISSN
1005-0302
Source
Journal of Materials Science & Technology: an international journal in the field of materials science, 108, 270-280
Bibliographical note
Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.
Part of collection
Institutional Repository
Document type
journal article
Rights
© 2022 Hyun Chung, Dae Woong Kim, Woo Jin Cho, Heung Nam Han, Yuji Ikeda, Shoji Ishibashi, F.H.W. Körmann, Seok Su Sohn