X-ray photoelectron spectroscopy studies of Ti1-xAlxN (0 ≤ x ≤ 0.83) high-temperature oxidation: The crucial role of Al concentration

The resistance to high-temperature oxidation of Ti1-xAlxN films determines performance in numerous applications including coated cutting tools. Here, we present a comprehensive study covering Ti1-xAlxN films with 0 ≤ x ≤ 0.83 annealed in air for 1 h at temperatures Ta ranging from 500 to 800 °C. Layers are grown by the combination of high-power impulse and dc magnetron sputtering (HiPIMS/DCMS) in Ar/N2 atmospheres. We use X-ray photoelectron spectroscopy to study the evolution of surface chemistry and to reconstruct elemental distribution profiles. No dependence of oxidation process on the phase content, average grain size, or preferred orientation could be confirmed, to the accuracy offered by the employed X-ray diffraction techniques. Instead, our results show that, under the applied test conditions, the Ti1-xAlxN oxidation scenario depends on both x and Ta. The common notion of double-layer Al2O3/TiO2 oxide formation is valid only in a limited region of the x-Ta parameter space (Type-1 oxidation). Outside this range, a mixed and non-conformal Al2O3-TiO2 layer forms, characterized by larger oxide thickness (Type-2 oxidation). The clear distinction between different Ti1-xAlxN oxidation scenarios revealed here is essential for numerous applications that can benefit from optimizing the Al content, while targeting a given operational temperature range. •Oxidation resistance of Ti1-xAlxN films with 0 ≤ x ≤ 0.83 is studied by XPS.•Al content has a crucial influence on the Ti1-xAlxN oxidation scenario.•Double-layer stoichiometric Al2O3/TiO2 oxide forms only in a limited range of x and anneal temperatures.•Outside this region, non-conformal Al2O3-TiO2 layer grows, characterized by larger oxide thickness.•This finding is essential for applications that can benefit from optimizing the Al content.