Metastable Ti 1-x Al x N (0.4 ≤ x ≤ 0.76) films are grown using a hybrid approach in which high-power pulsed magnetron sputtering (HIPIMS) is combined with dc magnetron sputtering (DCMS). Elemental Al and Ti metal targets are co-sputtered with one operated in HIPIMS mode and the other target in DCMS; the positions of the targets are then switched for the next set of experiments. In both cases, the AlN concentration in the co-sputtered films, deposited at T s = 500 °C with R = 1.5-5.3 Å/s, is controlled by adjusting the average DCMS target power. Resulting films are analyzed by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, elastic recoil detection analysis, and nanoindentation.Mass spectroscopy is used to determine ion energy distribution functions at the substrate. The distinctly different flux distributions obtained from targets driven in HIPIMS vs. DCMS modes allow the effects of Al n+ and Ti n+ (n = 1, 2) ion irradiation on film growth kinetics, and resulting properties, to be investigated separately. Bombardment with Al n+ ions (primarily Al + in the Al-HIPIMS/Ti-DCMS configuration) during film growth leads to NaCl-structure Ti 1-x Al x N (0.53 ≤ x ≤ 0.60) films which exhibit high hardness (> 30 GPa) with low stress (0.2 -0.7 GPa tensile). In contrast, films with corresponding AlN concentrations grown under Ti n+ metal ion irradiation (with a significant Ti 2+ component) in the Ti-HIPIMS/Al-DCMS mode have much lower hardness, 18-19 GPa, and high compressive stress ranging up to 2.7 GPa. The surprisingly large variation in mechanical properties results from the fact that the kinetic AlN solubility limit x max in 2 Ti 1-x Al x N depends strongly on, in addition to T s and R, the target power configuration during growth and hence the composition of the ion flux. AlN with x max 64 mol% can be accommodated in the NaCl structure under Al n+ ion flux, compared with 40 mol% for growth with Ti n+ flux. The strong asymmetry in film growth reaction paths is due primarily to the fact that the doubly-ionized metal ion flux is approximately two orders of magnitude higher from the Ti target, than from Al, powered with HIPIMS. This asymmetry becomes decisive upon application of a moderate substrate bias voltage, -60 V, applied synchronously with HIPIMS pulses, during growth.