AbstractWear in modern mechanical systems is characterised by ultra‐low wear rates in the range of a few nanometres per hour. Both the surfaces of the materials involved and their volumes undergo modification as regards morphology, crystalline arrangement, and chemical composition. The depth of tribological interactions for given conditions is in the order of a micrometre or less. Synchrotron‐based X‐ray diffraction and nano‐indentation were used to probe these thin modified zones. The specimens were taken from tribometric experiments employing the radionuclide technique as the ultimate tool to measure ultra‐low wear rates. To obtain different degrees of tribological interaction various loads and sliding velocities were applied. The specimens were classified according to the total power dissipated during the tribometric experiment.