Hard and wear and corrosion resistant Al–Ni type intermetallic layers, with an external Al 2 O 3 zone, were successfully produced on Inconel 600 using a duplex method. The duplex method combines glow discharge assisted oxidizing with pre-coating the Inconel substrate with aluminum by magnetron sputtering. The oxidizing process carried out at 560°C for 4h leads to a diffusion-induced transformation of the aluminum coating and adjacent Inconel into a 15μm thick composite layer of Al 2 O 3 +AlNi+AlCr 2 +AlNi 3 +Cr(Fe,Ni)+Ni(Cr,Fe,Al). The structure of the layer was examined in cross-section by transmission electron microscopy (TEM). The surface zone of the layer is constituted by nanocrystalline Al 2 O 3 covering the main zone of the AlNi layer. In this zone, near its border with the oxide zone, are small agglomerates of nanocrystalline Al 2 O 3 . The upper and thicker part of the AlNi zone also contains precipitates of the AlCr 2 phase. The AlNi zone is separated from Inconel by a diffusion zone of Ni(Cr,Fe,Al). In this region grains of AlNi 3 are found with groups of Cr(Fe,Ni) phase grains. As a consequence, the region is locally strongly enriched with chromium. This suggests that the formation of AlNi induces an uphill diffusion of chromium into the Inconel substrate.