Toward nanostructuring of Heusler Fe2VAl compound via hot deformation for the improvement of the thermoelectric properties: Groundworks

Details

Supervisors

Jacques, Pascal

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil en chimie et science des matériaux, à finalité spécialisée

Abstract

enThe Fe₂VAl Heusler compound has emerged as a promising thermoelectric material due to its abundance, non-toxicity, and moderate cost, aligning well with the growing need for scalable energy-harvesting technologies. However, its high thermal conductivity and brittle behavior at room temperature limit its performance. Its higher ductility compared to conventional brittle semiconductors opens pathways for microstructural tuning. This thesis investigates the potential of hot rolling as a scalable thermomechanical route to induce nanostructuring in Fe₂VAl-based alloys and improve their thermoelectric performance. Three compositions—Fe₂VAl₀.₉Si₀.₁, Fe₂V₀.₉₇Ti₀.₀₃Al, and Fe₁.₉₆V₀.₉₃Ta₀.₁₁Al—were studied in sintered and cast forms, followed by hot rolling at 1523 K with 50% deformation. Key findings include the observation that sintered precursors promote more extensive recrystallization and recovery than cast samples, attributed to a higher defect density. Grain refinement was achieved to varying extents across compositions, with Fe₁.₉₆V₀.₉₃Ta₀.₁₁Al showing the most promising thermoelectric performance, which however did not reach the state of the art. No direct correlation between ordering and recrystallization could be established, although their interaction remains a critical question for future studies. This work highlights the role of precursor microstructure and alloy composition in tailoring thermomechanical treatments for Fe₂VAl-based thermoelectrics and lays the groundwork for further exploration of hot rolling as a scalable nanostructuring method.