Oxidation behavior of Ti.sub.2AlC MAX-phase foams in the temperature range of 600-1000 °C

The isothermal oxidation behavior of Ti.sub.2AlC gel-cast foams with an almost completely open porosity of 87 vol% was investigated in the temperature range of 600-1000 °C, in static air, and for exposure times of up to 6.5 h. It was found that the oxidation process obeyed the parabolic rate law. The determined parabolic oxidation rate constants were low, indicating that the material's resistance to oxidation at high temperatures was very good, especially given its highly porous form. The nature of the scale formed on the strut surface of Ti.sub.2AlC foams changed significantly with increasing oxidation temperature. After oxidation at 600 °C, gaps/cracks were observed between Ti.sub.2AlC layers on the strut surface, and the oxidation products were mixed Ti and Al oxides. At 700-800 °C, the scales were integrated and composed of Ti and Al oxides. At 900-1000 °C, the oxidation products were composed of large elongated plates of TiO.sub.2 (rutile) and small, needle-like Al.sub.2O.sub.3 (corundum) grains.