Simulation of temperature and stress distributions in functionally graded materials synthesized by a spark plasma sintering process

A coupled electrical-thermal-mechanical finite element model is established to systematically investigate the temperature and stress distributions in a functionally graded material (FGM) based on Ti and TiB during a spark plasma sintering (SPS) process. The simulation results indicate that a stable axial temperature gradient in the specimen can be achieved using a die with an area-changing cross-section in the SPS process, thereby providing a beneficial condition for FGM sintering. The stress and the stress gradient are high at the bottom of the specimen, possibly leading to microstructural heterogeneity and cracks among adjacent layers. The simulation results also suggest that the temperature and stress gradient increase as the heating rate increases. The corresponding SPS experiments verified the simulation results and proved the superiority of the specially designed die.