The influence of the oxygen partial pressure on the ion nitriding of aluminium – An investigation by means of real time elastic recoil detection analysis

Abstract Aluminium is known to be a difficult candidate for successful nitriding. It exhibits a dense native surface oxide layer that acts as a barrier for diffusional nitrogen transport. To investigate the influence of the oxygen partial pressure, samples of pure polycrystalline Al were ion nitrided at different oxygen partial pressures from a hot filament ion source. Before and during the nitriding process depth profiling of nitrogen and oxygen has been performed by real time elastic recoil detection analysis. The oxygen partial pressure plays a crucial role for the evolution of the surface oxide layer and thus for the nitriding result. If the surface oxide layer is removed an AlN-layer grows. The evolution of the oxide layer is compared to semi-quantitative considerations on the interplay of sputtering and oxidation. A criteria for the removal of the surface oxide layer is given.