Nanomechanical characterization of thin FeXN (X=Ta, Ti) films deposited by cosputtering from Fe, Ta and Ti targets on a Si/SiO2 substrate has been conducted using a nanoindenter. To fully understand the influence of the substrate on the measurement of film properties a continuous measure of the hardness and modulus as a function of depth was performed. The hardness of both FeTa and FeTi films was improved with the incorporation of nitrogen due an associated reduction in the grain size. However at increased flow rates of nitrogen a small softening effect was observed. For binary Fe((100-x))Ta-x a rapid increase in hardness was observed at x > 17% which was coincident with a structural transformation from the nanocrystalline to the amorphous state. In the binary Fe((100-x))Ti-x the addition of 3.2 at. % Ti increased the hardness by a solid solution strengthening mechanism. (C) 2000 American Institute of Physics. [S0021-8979(00)39608-6].