Near surface stress determination in Kr-implanted polycrystalline titanium by the X-ray sin2Ψ-method

Ion implantation has been performed on polycrystalline titanium samples with 180 keV Kr+ ions at various doses from 1 × 1015 to 5 × 1016 ions cm− 2 at room temperature. The samples where characterised by Rutherford backscattering spectrometry, positron annihilation lifetime spectroscopy and X-ray diffraction. By means of the sin2Ψ technique the near surface stress has been determined for both unimplanted and implanted samples. The initial stress state has been shown to be strongly tensile in the first 75 nm below the surface, and weakly compressive deeper inside. The main effect of the implantation process was to relax the pre-existing tensile stress in the track region. An additional compressive stress was introduced deeper in the sample and could be attributed to the presence of larger defect clusters.