Effect of B on the Microstructures and High Temperature Oxidation Resistance of a Nb-Si System In Situ Composite
Nb-16Si-24Ti-6Cr-6Al-2Hf-xB(x=0, 0.5, 1, 2, 4, 6) in situ composites were prepared by arc-melting. Microstructure and the effect of boron on 1250C oxidation resistance of the composites were investigated by scanning electron microscopy(SEM) and X-ray energy disperse spectrum(EDS) as well as X-ray diffraction(XRD). The experimental results showed that the high temperature oxidation resistance of the alloy was remarkably improved by adding proper amount of boron. This may be resulted from several beneficial roles of boron, i.e., boron improves the resistance of Nb5Si3 by solid solution strengthening, inhibits the diffusion of oxygen in the matrix, improves the adherence between the oxide scale and the substrate and increases the cracking resistance of the oxide scale.
Yafang Han et al.
A. Q. Liu et al., "Effect of B on the Microstructures and High Temperature Oxidation Resistance of a Nb-Si System In Situ Composite", Materials Science Forum, Vols. 546-549, pp. 1489-1494, 2007