Development of silicide coatings over Nb–NbCr2 alloy and their oxidation behavior at 1250 °C

The aims of this study were to develop silicide coatings for Nb–NbCr2 alloy and to evaluate their oxidation behavior. Both of the coatings prepared by single deposition of Si and co-deposition of Si–Y were composed of (Nb,Cr)Si2 and (Cr,Nb)Si2, showing a similar structure. After oxidation at 1250 °C for 50 h, the weight gains of the bare alloy and the un-modified silicide coating were 246.9 and 90.3 mg/cm2 respectively, while the weight gain of Y-modified silicide coating was only 13.1 mg/cm2. The introduction of Y3 + in the scale showed a suppressing effect on the outward diffusion of chromium cations and the inward migration of oxygen anions, thereby retarding the oxide scale growth rate of the silicide coating at 1250 °C in static air.