Influence of different atmospheres on the thermal decomposition of Al-Cr-N coatings

Metastable cubic (c) AlCrN coatings decompose during thermal annealing into their stable phases Cr and hexagonal (h) AlN under the release of N2. We show that the onset temperature To and amount of N2 release depend on the ambient atmosphere. For c-Al0.56Cr0.44N only a partial dissociation into h-AlN and h-Cr2N with To ∼ 1180 deg. C occurs during annealing in N2 up to 1450 deg. C. Experiments in synthetic air to 1450 deg. C yield a complete oxidation to (Al0.56Cr0.44)2O3