Leveraging Additive Manufacturing to Tailor Thermoelectric Device Configuration, Leg Shape and Transport Properties

Additive manufacturing enables unprecedented customization of thermoelectrics at multiple lengths scales – from nanoscale inclusions to macroscale device shape – potentially all with one manufacturing process. We explore the process-structure-property relationship for laser-based additive manufacturing (specifically laser powder bed fusion) of thermoelectric materials for low and high temperature applications. We determined the process parameters required to form high density parts, and we characterized the nano- and micro-structural features formed in the printed parts. Simulations of the spatial and temporal temperature gradients during processing were used to determine solidification rates and thus predict grain structure, such as the distribution of equiaxed versus columnar grains; the predicted grain structure was compared to the experimentally observed grain structure. Thermoelectric properties (Seebeck coefficient, electrical conductivity, and thermal diffusivity) of printed bulk parts were measured as a function of temperature. The results provide insight about how additive manufacturing can be used to engineer thermoelectric materials and devices at multiple length scales.