Based on their excellent thermal stability and mechanical properties ceramic-like hard coatings are highly valued for various industrial applications. Here we study the effect of additional AlN layers (3 or 10 nm thin) on the mechanical and thermal properties of cubic CrN, Cr0.4Al0.6N and Cr0.37Al0.6Y0.03N. To focus our research on the influence of the additional layers, but minimizing the influence of the additional phase, we kept the overall AlN-layer content at a minimum (<14%). The hardness of the cubic Cr-based nitride layers is not influenced by the addition of coherently grown 3 nm thin AlN layers, due to their small overall content. The formation of wurtzite AlN, for the similar to 10 nm thin layers, breaks the coherency to the cubic Cr-based nitride layers. Thereby re-nucleation is promoted, resulting in a smaller grain size and consequently an actual hardness increase of about 3 GPa for CrN/AlN, Cr0.4Al0.6N/AlN and Cr0.37Al0.6Y0.03N/AlN coatings, respectively, when compared to the monolithically grown cubic Cr-based nitrides or the multilayers containing c-AlN. Both multilayer types, with 3 and 10 nm thin AlN layers, exhibit a similar dependence of their hardness on the annealing temperature. The hardness maximum of 36 GPa was obtained for the Cr0.37Al0.6Y0.03N/AlN multilayers after annealing at 900 degrees C. This study clearly demonstrates that even a small addition of thin AlN layers to CrN and Cr0.37Al0.6Y0.03N nitride layers increases their mechanical response to annealing treatments. (c) 2012 Elsevier B.V. All rights reserved.