Effects of W on high-temperature antioxidative properties of Nb/Nb_5Si_3 composite

摘要

The multi-component Nb-Si system in-situ composites with composition of Nb-20Si-5Al-15Ti-xW (at.%) were prepared by Spark Plasma Sintering (SPS) technology. The high temperature oxidation behavior and microstructure of the alloy were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron probe microscopy (EPMA). The results show that the microstructure of the composite consists of (Nb, Ti, W)ss, α-Nb_5Si_3, γ-Nb_5Si_3 and (Nb, Ti, W)_5Si_3 phase. With an increase of W addition, the oxidation resistance of the composites at 800°C decrease firstly and then increase. At 1100°C the addition of W decreased the oxidation resistance during the first 40h, then changed to increase the oxidation resistance. Pest oxidation behavior was exhibited by the Nb-20Si-5Al-15Ti-xW. The oxidation resistance of the composite at 1100°C is better than at 800°C because the oxide scale is more compact structure.