"Investigation of oxidation behavior and evolvement of grain morphology of Fe-Cr-Al alloy at 1200℃ and 1300℃"

The development of surface oxide scale and evolvement of spallation mechanism of a Fe-21Cr-5.6Al superalloy was investigated at 1200°C and 1300°C. The oxidation kinetic curves were obtained through measuring the weight gain isothermally with different time duration. The morphology of oxide scale and grain structure was observed through SEM/EDX, and the phase structure was analyzed by XRD. The results show that the oxidation process followed the parabolic law and a higher oxidation rate was achieved at 1300°C. Different morphology and phase composition was found in oxide scale of different temperature with equal time duration. Typical buckling morphology was observed when subjected to 1200°C and equi-aixed grain with multiple voids was found near the superalloy surface. A thicker and flat oxide layer was formed at 1300°Cand the grain near the interface stretching vertically to alloy surface was coarse and compact. High temperature triggered a fast transportation of element inside the alloy and the oxide layers after 50h oxidation at test temperature were consist of an outer corundum layer containing trace of Fe, Mg, C, and an inner Cr doped alumina layer. The appearance of top surface and spallation area manifest a transition of spallation mechanism due to temperature rise.