Investigation of the microstructure related high temperature oxidation behaviour of Fe-25Al-5Cr-0.5Zr and Fe-25Al-5Cr-0.5Zr+TiC at 700 degrees C in air

摘要

The discontinuous oxidation behaviour of Fe-25Al-5Cr-0.5Zr and Fe-25Al-5Cr-0.5Zr + TiC was investigated at 700 degrees C in air. The iron aluminides were oxidised for up to 1003 h using thermogravimetric analysis (TGA). DSC measurements were performed to analyse the transition temperature of D0(3)/B2 phase. OLM, SEM/EDX and XRD were utilized to evaluate formed scales and internal protrusions. The results show the presence of Fe2O3, ZrO2 and metastable gamma- and theta-Al2O3 at 700 degrees C. Furthermore, a decrease in the oxidation rate due to TiC addition, was observed. This is attributed to the reduced inner selective phase oxidation, which is dependent on the phase manifestation of (Fe,Al)(2)Zr and zirconium carbides.