Improvement of oxidation resistance of Nb-Ti-Si based alloys with additions of Al, Cr and B at different temperatures

The effects of Cr, Al and B addition on the microstructure and high-temperature oxidation behaviors (at 1200, 1250 and 1300 degrees C) of Nb-Ti-Si based alloys were investigated. The results showed that the addition of Cr stabilized alpha-Nb5Si3, while Al promoted the formation of beta-Nb5Si3 and adding B promoted the formation of gamma-Nb5Si3. Among the three elements, Al and Cr were beneficial to oxidation resistance at 1200 degrees C, and B was favorable to the oxidation resistance at 1300 degrees C. At 1250 degrees C, Al and B had the same effects on the improvement of oxidation resistance. The ratio of these alloying elements might play an important role in enhancing oxidation resistance. The oxidation resistance of the three kinds of silicides was compared, and the sequence was: gamma-Nb5Si3> beta-Nb5Si3> alpha-Nb5Si3. To predict the effects of the investigated alloying elements on the oxidation resistance of Nb-Ti-Si based alloys in a wider range of concentration, an artificial neural network (ANN) model was established, showing excellent accuracy and generalization ability. With the instructions of the ANN model, the oxidation resistance can be optimized with less additions of alloying elements.

Automated summary

The effects of Cr, Al, and B on the microstructure and high-temperature oxidation behaviors of Nb-Ti-Si based alloys were studied. Among the three elements, Al and Cr were beneficial to oxidation resistance at 1200°C, while B was favorable at 1300°C. The ratio of these alloying elements may play a significant role in enhancing oxidation resistance.