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

► Gradient structured Ta compacts were synthesized by means of PAS. ► Annealing results in gradual disappearing of gradient structure. ► Strength was further improved after annealing. ► For low N content compact, annealing results in a drop in ductility. ► For high N content compact, fracture strain keeps unchanged after annealing.