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Engineering heterogeneous microstructure by severe warm-rolling for enhancing strength-ductility synergy in eutectic high entropy alloys
journal contribution
posted on 2019-09-01, 00:00 authored by S R Reddy, S Yoshida, U Sunkari, A Lozinko, Jithin JosephJithin Joseph, R Saha, Daniel FabijanicDaniel Fabijanic, S Guo, P P Bhattacharjee, N TsujiThe microstructure and mechanical properties of a (L12+B2) AlCoCrFeNi2.1 eutectic high entropy alloy (EHEA) processed by severe warm-rolling were investigated in the present work. The EHEA was successfully warm-rolled up to 90% reduction in thickness at 400 °C, 600 °C and 750 °C. Considerable differences in the microstructural evolution were identified during warm-rolling at the three temperatures. The L12 phase in the EHEA was disordered due to severe warm-rolling at 400 °C and 750 °C, while a predominantly ordered structure was retained in the EHEA warm-rolled at 600 °C. This anomalous behavior could be adequately explained by the sluggish ordering kinetics at lower deformation temperatures. The EHEA warm-rolled at 750 °C showed an extremely heterogeneous microstructure featured by retained lamellar regions comprising of B2 and FCC lamellae with dispersed B2 phase inside the FCC, whereas the non-lamellar regions showed a mixture of ultrafine to nanocrystalline disordered FCC, ordered B2 and Cr-rich σ phases. The non-lamellar regions were scarce and nearly absent in the EHEA 90% warm-rolled at 600 °C and 400 °C, respectively. The remarkably heterogeneous microstructure of EHEA warm-rolled at 750 °C resulted in outstanding strength-ductility combination with tensile strength ~1635 MPa and elongation to failure ~18%. The results indicated tremendous potential for achieving superior mechanical properties in heterogeneous EHEAs processed by severe warm-rolling.
History
Journal
Materials science and engineering AVolume
764Article number
138226Pagination
1 - 12Publisher
ElsevierLocation
Amsterdam, The NetherlandsPublisher DOI
ISSN
0921-5093Language
engPublication classification
C1 Refereed article in a scholarly journalCopyright notice
2019, Elsevier B.V.Usage metrics
Keywords
Science & TechnologyTechnologyNanoscience & NanotechnologyMaterials Science, MultidisciplinaryMetallurgy & Metallurgical EngineeringScience & Technology - Other TopicsMaterials ScienceHigh entropy alloysWarm-rollingPhase transformationMicrostructureMechanical propertiesMECHANICAL-PROPERTIESLAMELLA STRUCTUREDESIGNRECRYSTALLIZATIONNANOSTRUCTURESTEMPERATURESTABILITYEVOLUTIONTEXTUREMechanical Engineering
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