Deformation behavior and strengthening effects of an eutectic AlCoCrFeNi2.1 high entropy alloy probed by in-situ synchrotron X-ray diffraction and post-mortem EBSD

Funding Information: JS, JGL, and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394). JGL acknowledges FCT – MCTES for funding the Ph.D. grant 2020.07350.BD. JPO acknowledges funding by national funds from FCT - Fundação para a Ciência e a Tecnologia, I.P. in the scope of the projects LA/P/0037/2020, UIDP/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N. The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872from the EU Framework Programme for Research and Innovation HORIZON 2020. HSK acknowledges the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (NRF-2021R1A2C3006662, NRF-2022R1A5A1030054). Yeon Taek Choi was supported by the Basic Science Research Program “Fostering the Next Generation of Researcher” through the NRF funded by the Ministry of Education [grant number 2022R1A6A3A13073824]. The raw/processed data required to reproduce the above findings cannot be shared at this time as the data also forms part of an ongoing study. Funding Information: JS, JGL, and JPO acknowledge Fundação para a Ciência e a Tecnologia (FCT - MCTES) for its financial support via the project UID/00667/2020 (UNIDEMI). JS acknowledges the China Scholarship Council for funding the Ph.D. grant (CSC NO. 201808320394 ). JGL acknowledges FCT – MCTES for funding the Ph.D. grant 2020.07350.BD . JPO acknowledges funding by national funds from FCT - Fundação para a Ciência e a Tecnologia , I.P., in the scope of the projects LA/P/0037/2020 , UIDP/50025/2020 and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostructures, Nanomodelling and Nanofabrication – i3N. The authors acknowledge DESY (Hamburg, Germany), a member of the Helmholtz Association HGF, for the provision of experimental facilities. Beamtime was allocated for proposal I-20210899 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020 . HSK acknowledges the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) ( NRF-2021R1A2C3006662 , NRF-2022R1A5A1030054 ). Yeon Taek Choi was supported by the Basic Science Research Program “Fostering the Next Generation of Researcher” through the NRF funded by the Ministry of Education [grant number 2022R1A6A3A13073824 ]. Publisher Copyright: © 2023 The AuthorsIn this work, high energy synchrotron X-ray diffraction was used during tensile testing of an as-cast eutectic AlCoCrFeNi2.1 high entropy alloy. Aside, from determining for the first time the volume fractions of existing phases, we further detail their role on the alloy deformation behavior. The two major phases, a soft disordered FCC and a hard ordered B2 BCC, were observed to exhibit a stress partitioning effect which can be used to modulate the mechanical response of the material based on the relative volume fraction of each phase. Dislocation density analysis revealed that the soft FCC phase had a significantly higher dislocation density right after the onset of plastic deformation. This is attributed to the existence of strain gradients across the lamellar structure, where the hard B2 BCC prevents free deformation of the FCC phase. Nonetheless, despite the increase of the dislocation density in the soft FCC phase, calculations of the strengthening effects induced by generation of dislocations are more significant in the hard B2 BCC phases, as this phase is primarily responsible for the strength increase in the alloy. Besides, the evolutions in dislocation density of the soft FCC and hard B2 BCC phases during tensile deformation obtained from synchrotron X-ray diffraction data are consistent with the evolution of KAM determined by EBSD characterization. Also, lattice strain analysis across two principal directions (parallel and perpendicular to the loading axis) reveals that for these specific orientations there is a preferential deformation of the hard FCC planes which can be related to the deformation response of specific lattice planes at distinct orientations, as well as to the phase partitioning stress behavior.publishersversionpublishe

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