Innovative Developpement of Silicon Germanium Alloy Enhanced with Nanoprecipitates by Additive Manufacturing

Thermoelectric (TE) devices is presented as an environmentally-friendly technology useful for several niche applications in electricity generation and cooling systems. Recent advances in additive manufacturing (AM) techniques, such as Laser Powder Bed Fusion (L-PBF), allow manufacturing of a wide range of materials, including TE materials. AM of TE materials open new possibilities in TE devices’ shapes that can facilitate their integration and improve their performance. This work presents the development of silicon germanium (SiGe) alloys by L-PBF process. The first attempt at producing this material resulted in a dense material with promising Seebeck coefficient and thermal conductivity, but its other properties were hindered by mechanical cracking occurring during L-PBF processing. To address this issue, a new approach was studied: nanoprecipitates formation during cooling. Nanoprecipitates can simultaneously enhance TE properties by scattering phonons, and enhance mechanical properties by acting as nucleating agents for silicon germanium matrix, and reduce grain size. It is the first time that such approach is studied in AM of TE materials. A specific study has been performed to define the best nanoprecipitates candidates. Three systems of nanoprecipitates were retained: SiC, WSi<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> and MoSi<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>. This work will present how these nanoprecipitates were chosen, then their impacts on SiGe structural and TE properties.