In-situ reactive synthesis of dense nanostructured β-FeSi2 by Spark Plasma Sintering

β-FeSi 2 is a promising material for thermoelectric application, especially if it can be nanostructured to decrease the lattice contribution to the thermal conductivity. It can be even more interesting if the entire chain of processes implemented to obtain it is not too time and energy consuming. In this paper we report a simple route to synthesize nano-β-FeSi 2 by combining mechanical milling and reactive spark plasma sintering of Fe-Si alloys. A map of the pressure-temperature conditions using a spark plasma sintering setup was performed and shows that it is possible to obtain nano-β-FeSi 2 pellets with a density above 90% using dwell times as short as 5 min. The impact, of both, the density and nanostructuring on the hardness of the β-FeSi 2 pellets obtained by this process are presented as well as the impact of the thermoelectric properties of the materials. • Dense nanostructured β-FeSi 2 was obtained by simple route. • β-FeSi 2 was obtained on a large P-T range by in-situ reactive Spark Plasma Sintering. • Large grain size of prealloys limits the full in situ reaction. • Relative density above 90% leads to enhanced mechanical properties.