Microstructures and high‐temperature oxidation behavior of directionally solidified Nb–Si‐based alloys with Re additions

Abstract

Abstract High‐temperature oxidation behavior of directionally solidified (DS) Nb–Si‐based alloys with Re additions was investigated at 1200 and 1250 °C, respectively. Microstructures and high‐temperature oxidation behavior of the alloys were characterized. Results show that the microstructures in vertical section of Nb–24Ti–15Si–4Cr–2Al–2Hf– x Re ( x = 0, 1, 3; at%) alloys grow parallel to the withdrawal direction and the cross section exhibits bud‐like structures. The bud‐like structures become finer with more Re additions. The weight gain of the Nb–24Ti–15Si–4Cr–2Al–2Hf–3Re alloy after oxidation at 1200 °C for 100 h is 198.1 mg·cm −2 , and it is a bit higher at 1250 °C. The other two alloys perform somewhat worse. The influence of Re addition on the oxidation resistance at 1250 °C is more significant than that at 1200 °C. Although Re addition does not benefit obviously the high‐temperature oxidation resistance of the DS samples, it does not compromise the oxidation resistance with a certain amount of Re additions in contrast with the alloy without Re addition.