By using nano-indentation, hardening mechanisms were investigated in steered-arc evaporated and electron-beam evaporated thin films. The films had columnar grains, with the column diameters ranging from 22 to 170nm in the steered-arc films and from 30 to 40nm in the electron-beam films. The Hall–Petch relationship was extended to hardness values of between 6 and 12GPa. Analysis of nano-indentation creep data (creep, load relaxation, rate change) revealed that, in the steered-arc films, thermally activated glide was rate-controlling, and that the grain size had little effect upon the underlying rate processes even down to 22nm. There was evidence, based upon X-ray diffraction and previous results, that the electron-beam films contained high densities of interstitial loops which resulted from Ar-ion bombardment during deposition. The creep data indicated that these loops affected the thermal activation of dislocations.

Activation Analysis of Deformation in Evaporated Molybdenum Thin Films. K.B.Yoder, A.A.Elmustafa, J.C.Lin, R.A.Hoffman, D.S.Stone: Journal of Physics D, 2003, 36[7], 884-95