Effect of thermal annealing on microstructure and mechanical properties of a gradient structured tantalum prepared by plasma activated sintering

Abstract Fully dense bulk tantalum compacts of two different nitrogen contents with gradient structure within an individual particle were successfully synthesized by means of plasma activated sintering (PAS). Annealing of the compacts induces disappearing of the gradient structure due to the promoted diffusion of nitrogen in Ta matrix accompanied by enhancement of the strength. For the compact with low nitrogen content of 0.09 wt.%, a drop in ductility was observed. While for the compact with nitrogen content of 0.215 wt.%, improved strength was obtained without sacrificing its ductility.