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Effect of temperature on small-scale deformation of individual face-centered-cubic and body-centered-cubic phases of an Al_(0.7)CoCrFeNi high-entropy alloy

Giwa, Adenike M. and Aitken, Zachary H. and Liaw, Peter K. and Zhang, Yong-Wei and Greer, Julia R. (2020) Effect of temperature on small-scale deformation of individual face-centered-cubic and body-centered-cubic phases of an Al_(0.7)CoCrFeNi high-entropy alloy. Materials and Design, 191 . Art. No. 108611. ISSN 0264-1275. https://resolver.caltech.edu/CaltechAUTHORS:20200302-140842584

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Abstract

High-entropy alloys (HEAs) represent an important class of structural materials because of their high strength, ductility, and thermal stability. Understanding the mechanical response of isolated phases of a FCC/BCC dual-phase HEA is integral to understanding the mechanical properties of these alloys in the bulk. We investigate the compressive response of single-crystalline cylinders with diameters between 400 nm and 2 μm excised from individual grains within FCC and BCC phases of the dual-phase Al_(0.7)CoCrFeNi HEA at 295 K, 143 K, and 40 K. We observed a “smaller is stronger” size effect in the yield strength as a function of pillar diameter, D, of both alloy phases for all temperatures, with a power-law exponent, m, decreasing with temperature for the FCC phase, and remaining constant for all temperatures in the BCC phase. We found reduced work-hardening rates and more extensive strain bursts during deformation at lower temperatures in all samples. We performed molecular dynamics simulations of similar FCC and BCC HEA compression that displayed deformation dominated by dislocation slip at all temperatures. We discussed theories of low-temperature strengthening in HEAs, compared them to our experimental data and assessed how they manifest in the observed temperature-dependent size effect and work-hardening.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.matdes.2020.108611DOIArticle
ORCID:
AuthorORCID
Greer, Julia R.0000-0002-9675-1508
Additional Information:© 2020 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Received 17 December 2019, Revised 18 February 2020, Accepted 27 February 2020, Available online 28 February 2020. A.M.G and J.R.G. would like to thank National Science Foundation (NSF) the Stanback Space Innovation Program and the Keck Institute of Space Studies (KISS) at Caltech for the financial support of the present research. The authors acknowledge Matt H. Sullivan at the Kavli Nanoscience Institute (KNI) at Caltech for help with the TEM sample preparation and Carol Garland for her assistance with the TEM analysis and experiments. Z.H.A, M.J.Z., and Y.W.Z. gratefully acknowledge the financial support from the Agency for Science, Technology and Research (A*STAR), Singapore (Grant No. A1898b0043) and the use of computing resources at the A*STAR Computational Resource Centre, Singapore. P.K.L. very much appreciates the support of the U.S. Army Research Office project (W911NF-13-1-0438 and W911NF-19-2-0049) with the program managers, Drs. M. P. Bakas, S. N. Mathaudhu, and D. M. Stepp. PKL thanks the support from the National Science Foundation (DMR-1611180 and 1809640) with the program directors, Drs J. Yang, G. Shiflet, and D. Farkas. Data availability: The processed size effect data required to reproduce these findings are available from the corresponding author upon request. The raw stress-strain data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study. CRediT authorship contribution statement: Adenike M. Giwa:Methodology, Investigation, Formal analysis, Writing - original draft.Zachary H. Aitken:Methodology, Investigation, Formal analysis, Writing - original draft.Peter K. Liaw:Conceptualization, Investigation, Methodology, Resources, Writing - review & editing.Yong-Wei Zhang:Conceptualization, Formal analysis, Investigation, Methodology, Supervision, Writing - review & editing.Julia R. Greer:Conceptualization, Formal analysis, Investigation, Methodology, Supervision, Writing - review & editing. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Group:Kavli Nanoscience Institute, Keck Institute for Space Studies
Funders:
Funding AgencyGrant Number
Keck Institute for Space Studies (KISS)UNSPECIFIED
Agency for Science, Technology and Research (A*STAR)A1898b0043
Army Research Office (ARO)W911NF-13-1-0438
Army Research Office (ARO)W911NF-19-2-0049
NSFDMR-1611180
NSFDMR-1809640
Subject Keywords:High-entropy alloys; Cryogenic temperature; Deformation mechanisms; Al0.7CoCrFeNi; Nanopillars; Dislocations; Nanoplasticity
Record Number:CaltechAUTHORS:20200302-140842584
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200302-140842584
Official Citation:Adenike M. Giwa, Zachary H. Aitken, Peter K. Liaw, Yong-Wei Zhang, Julia R. Greer, Effect of temperature on small-scale deformation of individual face-centered-cubic and body-centered-cubic phases of an Al0.7CoCrFeNi high-entropy alloy, Materials & Design, Volume 191, 2020, 108611, ISSN 0264-1275, https://doi.org/10.1016/j.matdes.2020.108611. (http://www.sciencedirect.com/science/article/pii/S0264127520301453)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101658
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:02 Mar 2020 22:16
Last Modified:16 Mar 2020 22:32

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