Élaboration et étude des propriétés thermoélectriques du Full-Heusler Fe₂TiSi obtenu par frittage réactif
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- Environmental and climate challenges require a gradual reduction in dependence on fossil fuels and an improvement in the energy efficiency of industrial processes. In this context, thermoelectric materials offer a way to recover waste heat by directly converting a temperature difference into electrical energy. Among Full-Heusler compounds, Fe₂TiSi is of particular interest because of its thermoelectric potential, its predicted semiconducting behavior, and its composition based on relatively abundant and low-toxicity elements. However, obtaining a homogeneous and properly ordered Fe₂TiSi phase remains challenging. This work investigates the formation of Fe₂TiSi directly from elemental iron, titanium, and silicon powders by reactive sintering, as well as the relationship between the resulting states and their thermoelectric properties. Several processing routes and heat treatments were compared. The microstructure and local compositions were characterized by SEM-EDX, while X-ray diffraction was used to identify the phases present. The thermoelectric properties were evaluated through measurements of the Seebeck coefficient, electrical conductivity, and, for some samples, thermal conductivity. A composition containing vanadium (V) and copper (Cu) was also investigated as a complementary study. The results reveal domains with compositions close to Fe₂TiSi and several X-ray diffraction reflections compatible with this phase. However, the samples remain multiphase, and the investigated heat treatments do not lead to complete homogenization. The measured thermoelectric properties remain low, with Seebeck coefficients on the order of a few µVK⁻¹, and are strongly influenced by the multiphase nature of the samples. The effect of adding V and Cu remains difficult to isolate because of their heterogeneous distribution. Thus, controlling the initial reactions and interdiffusion appears to be a priority before any optimization of the thermoelectric properties.