Alumina/aluminum composites formed by the directed oxidation of aluminum using magnesia as a surface dopant

Al2O3/Al composites have been formed by the directed oxidation of pure Al doped with MgO powder. Thermal gravimetric analysis was used to characterize reaction kinetics. Optical and scanning electron microscopy and SEM coupled with microanalysis were used to characterize the microstructure of product. Directed oxidation is initiated without an incubation period. The particle size of the MgO powder determines the initial microstructure. Mg is retained in some form at the growth surface after the disappearance of the original MgO; however, there is a continuous loss of Mg from the system. The presence and distribution of the Mg compounds play a key role in the directed oxidation.