The oxidation mechanism of nanostructured Y-Zr-O complex oxide dispersion-strengthened Mo alloys

The oxidation behavior of nanostructured Y-Zr-O complex oxide dispersion-strengthened Mo alloys was investigated using the thermogravimetric analysis in synthetic air at 300 °C, 600 °C, and 700 °C for 2 h, respectively. The Mo alloys have a higher weight gain than pure Mo, indicating a deterioration in oxidation resistance, which is derived from the ultrafine grain structure by providing more boundaries for the diffusion of oxygen and accelerating the oxidation rate. Whereas a low weight gain followed by a slow rate of weight loss is observed with increasing Zr addition, revealing the oxidation resistance is improved as the dissolved Zr concentration in the matrix increases. The dissolved Y and Zr promote the formation of the Y-Zr-Mo-O phase in the outer MoO3 layer, which suppresses the formation and volatilization of MoO3. •A deterioration in the oxidation resistance of Mo alloys is observed owing to the ultrafine-grained structure.•The oxidation resistance of Mo alloys is improved by increasing the dissolved Zr concentration.•The dissolved Y and Zr promote the formation of Y-Zr-Mo-O phase, which suppresses the formation and volatilization of MoO3.