Field-assisted sintering technique (FAST), also called electric-current-assisted sintering (ECAS) or spark plasma sintering (SPS), is a powder metallurgy process that employs electric current to generate heat (Joule effect) while simultaneously applying pressure to achieve consolidation and densification of particulate material. The complexity of the process stems from the interdependence of electrical, thermal and mechanical phenomena. Modelling this complex process requires a multiphysics approach that combines electrical, thermal, and mechanical problems. In this work, a coupled microscopic thermo-electro-mechanical model is developed within the discrete element framework. In the discrete element method (DEM), spherical discrete elements represent powder particles, which makes the DEM a suitable tool for micromechanical modelling of the SPS process. The model is based on the sintering geometry assuming a cylindrical neck connection between particles. Additional thermal and electrical resistance is introduced at the neck. In the development of the model, first, each physical phenomenon was addressed separately and then combined to build a complete coupled model. Thermal and electrical modelling capabilities were investigated. The DEM model was used to simulate thermal and electrical conduction and evaluate the effective properties of partially sintered porous material with a heterogeneous microstructure. Then, the DEM model was applied to model thermo-electric phenomena in the FAST process. In the present work, formulation of a fully coupled thermo-electro-mechanical model will be presented. The model will be applied to simulate FAST process of NiAl powder. Numerical results will be compared with own experimental data.