Finite element analysis of temperature and stress fields during the selective laser melting process of thermoelectric SnTe

A three dimensional nonlinear transient thereto-mechanically coupled finite element model (FEM) is introduced to analyze the temperature and stress fields during the selective laser melting (SLM) of thermoelectric (TE) SnTe. Considering the powder-to-solid transition and the latent heats of melting and vaporization, we simulate the temperature distribution near the molten pool and the residual stress inside the printed material at room temperature under different laser processing parameters. The calculated results indicate that vaporization gradually weakens as the laser power decreases and the scanning speed increases. Within the optimum forming window, the residual stress rises with the increasing laser power and decreasing scanning speed. The thermal stress mainly concentrates in the middle of the first scanning track, the terminal of each scanning track, and the edges of the forming surface, which is well consistent with the experimental results. This work has laid a significant foundation for rapid manufacturing of bulk SnTe thermoelectric materials using the selective laser melting process and will serve as a guide for laser processing of other thermoelectrics and perhaps even complete thermoelectric modules.