Influence of sintering temperature on microstructures of Nb/Nb5Si3 in situ composites synthesized by spark plasma sintering

Taking the use of Nb and Si elemental powders as raw materials, Nb/Nb5Si3 composites were successfully fabricated by a spark plasma sintering (SPS) technology. The influence of sintering temperatures on microstructures of the synthesized composites was mainly investigated. The results show that there exists a critical sintering temperature Tc (1400 °C) in the synthesis of Nb/Nb5Si3 composites by SPS technology. When sintering temperature is lower than Tc, an intermediate Nb3Si phase is produced in the fabricated samples. Moreover, the relative density of the samples is lower. Only if the sintering temperature is higher than Tc, the intermediate Nb3Si phase is thoroughly eliminated, Nb particles become a finer size and desirable Nb/Nb5Si3 composites up to 99.59% theoretic density are achieved.