Effects of element proportions on microstructures of Nb/Nb5Si3 in situ composites by spark plasma sintering

Nb/Nb5Si3 composites were successfully fabricated by a spark plasma sintering (SPS) technology. The effects of element (Nb and Si) proportions on the microstructures of the synthesized composites were mainly investigated. The results show that element proportions strongly affect the microstructures of Nb/Nb5Si3 composites; Nb/Nb5Si3 in situ composites up to 99.59% of theoretical density were fabricated by SPS technology, and the microstructures of the fabricated composites comprise the synthesized Nb5Si3 and the uniformly distributed Nb particles. Moreover, with the increase in the Si content from 6% to 20% (atom fraction), the volume fraction of the synthesized Nb5Si3 in the composites increases, whereas the content and size of Nb particles decrease obviously. The higher shrinkage and densification for Si content (16 at.% and 20 at.%) close to the eutectic composition take place. When sintering temperature over 1400 °C, the shrinkage obviously retards and finally stops.