Microstructure and High Temperature Oxidation Behavior of Aluminum Alloyed Cast Irons

The present study postulates the phases formed/oxidation resistance of aluminum alloyed cast irons (0 to 4 wt% Al) based on scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS), X-ray diffraction and oxidation test. Mechanisms of the oxidation of the alloys were determined at high temperatures (700-1000 oC). A direct relationship between Al content and oxidation temperature was found; at a lower oxidation temperature (less than 800 oC), low oxidation resistances were obtained characterized by formation of FeO, Fe3O4 and Fe2O3. With increasing the Al content, the performance of the alloys enhanced noticeably. Scale thickness was reduced progressively with increasing aluminum content. Under all testing conditions, the oxidation kinetics is parabolic with different parabolic rate constants