MICROSTRUCTURAL AND CHEMICAL CHARACTERIZATION OF ION-BEAM MIXED FE/AL2O3 INTERFACE - EFFECT ON ADHESION ENHANCEMENT

Metallic iron layers (approximately 60 nm) deposited on sapphire substrates have been mixed at room temperature with various ions (Ne, Ar, Kr, Xe) in wide dose and energy ranges. Microstructural characterization of the interface has been performed at the atomic scale using high-resolution transmission electron microscopy observations on cross-sectioned samples. Complementary measurements with conversion electron Mossbauer spectrometry (CEMS) and X-ray photoelectron spectrometry (XPS) give chemical information on the nature of the nonequilibrium phases formed at the interface. The mixed zone at the interface concerns few atomic planes and no long-range diffusion takes place at room temperature in those metal-ceramic systems. A significant enhancement of adhesion has been measured by the pin pull test for the mixed samples with a strong dependence on the energy deposition at the interface. These results will be discussed taking into account the microstructural and physicochemical aspects as well as the energy deposition in individual cascades during the primary ballistic phase (approximately 10(-13) s) of the ion beam mixing process.