High-Temperature Oxidation Behavior of Nb 3 Al Based Alloys

Oxidation behavior of Nb3Al has been studied in the temperature range from room temperature to 1500°C. It was revealed in this study that the oxide scale that formed at elevated temperatures was not protective against the propagation of the oxidation front. The products of oxidized Nb3Al alloys melted below 1500 °C, even though the melting point of Nb3Al is 1960°C. We expected that the addition of third elements would improve oxidation resistance because atomic sizes smaller than Nb and Al might reduce the solubility and diffusivity of oxygen in the alloy. The elements V, Mn, Fe, Mo, Ta, W and Re were added as the third element for the examination of oxidation resistance. The oxidation resistance tests were carried out by measuring weight gain during temperature elevation and during isothermal heating in air. It was concluded that the addition of Re or Mo improved the oxidation resistance for Nb3Al alloys.