Cr1-xAlxN coatings are promising candidates for advanced machining and high temperature applications due to their good mechanical and thermal properties. Recently the authors have shown that reactive magnetron sputtering using Cr-Al targets with Al/Cr ratios of 1.5 and Y contents of 0, 2, 4, and 8 at % results in the formation of stoichiometric (Cr1-xAlx)(1-y)YyN films with Al/Cr ratios of similar to 1.2 and YN mole fractions of 0%, 2%, 4%, and 8%, respectively. Here, the impact of Y on thermal stability, structural evolution, and thermo-mechanical properties is investigated in detail. Based on in situ stress measurements, thermal analyzing, x-ray diffraction, and transmission electron microscopy studies the authors conclude that Y effectively retards diffusional processes such as recovery, precipitation of hcp-AIN and fcc-YN, grain growth, and decomposition induced N-2 release. Hence, the onset temperature of the latter shifts from similar to 1010 to 1125 degrees C and the hardness after annealing at T-a=1100 degrees C increases from similar to 32 to 39 GPa with increasing YN mole fraction from 0% to 8%, respectively. (C) 2008 American Vacuum Society.