During wetting experiments of pure aluminum on the (0001) plane of sapphire, an aluminum sample was unintentionally contaminated with 31 atoms/parts per million of iron. Transmission electron microscopy investigations of the sample after cooling showed the formation of FeAlO3 at the aluminum-Al2O3 interface. Formation of FeAlO3 confirms the existence of a high oxygen activity at the liquid aluminum-sapphire interface, which is considered to be the reason for the strong adhesion between aluminum and Al2O3. A low indexed orientation relationship between FeAlO3 and Al2O3 was determined, where [2 (2) over bar1](FeAlO3) parallel to [1 (1) over bar 00](Al2O3) and (110)(FeAlO3) parallel to (0001)(Al2O3).