Study on Interface Reactions between Nb-Si System In Situ Composite and Ceramics
A Nb-Si system in-situ composite Nb-16Si-24Ti-6Cr-6Al-2Hf(at%) was fabricated using vacuum arc melting method, and then was metallurgically reacted with four kinds of ceramics ZrO2, Y2O3 stabilized ZrO2, Y2O3, SiC+Si3N4 at elevated temperature. The microstructures in the interface reaction zones were investigated by SEM and EDS. The results showed that different extent chemical reactions between the composite and these four kinds of ceramics took place. It has been found that HfO2 riched layer formed near the interfaces between the Nb-Si in-situ composite and three ceramics of ZrO2, Y2O3 stabilized ZrO2 and Y2O3, and thickness of the reaction zones were about 100μm, 10μm, 1μm respectively. C and N elements in SiC+Si3N4 ceramic diffused to the composite at elevated temperature, and a new phase that rich of Ti, C and N elements appeared nearby the interface and accumulated inhomogenously. It may be concluded that the interface reactions of both ZrO2 and SiC+Si3N4 with Nb-Si composite were very violent, therefore they are not suitable as face-coat materials of shell molds for investment casting; the interface reaction of Y2O3 stabilized ZrO2 and Nb-Si composite was slighter than ZrO2 and SiC+Si3N4, and it can be used as face-coat material of shell molds, the interface reaction of Y2O3 and Nb-Si composite was very slight, and is recommended as an ideal face-coat materials of shell molds.
Yafang Han et al.
J. J. Yu et al., "Study on Interface Reactions between Nb-Si System In Situ Composite and Ceramics", Materials Science Forum, Vols. 546-549, pp. 1495-1500, 2007