Tiamiyu, Ahmed AladeAdegbite, Muyideen2024-08-292024-08-292024-08-27Adegbite, M. (2024). Design, development, and deformation behavior of Cantor-derived high-entropy alloys for nuclear structural applications (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/119546As the global population approaches the projected 10-billion mark by 2050, it raises the need for clean and sustainable energy sources such as nuclear energy to meet the future energy demand. This has led to the ongoing search for suitable damage-tolerant materials for the accompanying structural components that must meet stringent properties for proposed Generation IV nuclear reactors. As a starting point to find suitable high-entropy alloys (HEAs) for these nuclear structural applications, this thesis first catalogs the already existing HEAs to understand their mechanical behavior. In addition, this cataloging helps with mechanical data aggregation (between 10-5 and 105 s-1 strain rate) of HEAs. It leads to the identification of the uncharted strain rate regimes and HEAs with limited mechanical data, the development of a deformation mechanism map for FCC-HEA—CoCrFeMnNi, and the development of simple yield-strength prediction models for FCC and BCC-HEAs. One of the HEAs with limited mechanical data and already proposed for nuclear structural applications is the Cantor-derived Al0.3CoCrFeNi. However, Al0.3CoCrFeNi’s metastability could be deleterious in nuclear structural applications where stable single-phase FCC materials are preferred for their low void swelling property. Guided by the FCC stabilizing effect of Mn as against the BCC stabilizing effect of Al, this thesis proposes, designs, and develops a novel Cantor-derived Mn0.3CoCrFeNi HEA as a potential substitute for Al0.3CoCrFeNi. The substitutional effect of Al and Mn on the microstructure and mechanical response of both Cantor-derived HEAs is then examined as a first experimental installment towards their candidacy for nuclear structural applications. The microstructural differences and mechanical responses—Vicker’s hardness (HV), uniaxial quasi-static (10-3 s-1), and dynamic strain rate (2300 s-1) compression at room temperature are reported. Both HEAs had similar yield strength, except in the cold-rolled samples, and a unique dynamic strain aging (DSA) under room temperature/low strain rate conditions categorized as Type A serrations. Although dislocation slip and deformation twins are dominant deformation mechanisms in both HEAs; Mn0.3CoCrFeNi has a greater propensity to twin that improve its strain hardenability than Al0.3CoCrFeNi. This study clearly establishes that novel Mn0.3CoCrFeNi is microstructurally and mechanically more favored for nuclear structural applications than Al0.3CoCrFeNi.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.High-entropy alloysAl0.3CoCrFeNiMn0.3CoCrFeNiDynamic deformationPhase stabilityDynamic strain agingTwinning-induced plasticityNuclearStrain rate effectstrengthening mechanismsdeformation mechanismsMetallurgyMaterials ScienceEngineering--Mechanicalmaster thesis