Field ion microscopy study of the interactions between self interstitials and impurities in metals

The structures of specimens of technically pure tungsten (with an impurity level of ∼ 0.2%), W-5%Re and W-1.5%ThO2 alloys that were irradiated by La+, Ni+, and Cr+ ions with energies of 35 keV and fluences of between 1014 and 1016 ions/cm2 at room temperature have been studied by field ion microscopy. The spectrum of discovered defects (depleted zones, voids, monovacancies and interstitial atom-impurity complexes) has been described and their parameters have been determined. Some properties of self interstitial atom-impurity atom complexes in tungsten have been investigated: split configuration, mobility, crystallographic anisotropy of the exit to the surface, possibility of reconstruction under the influence of mechanical stresses and as a result of changes in the atomic surrounding. The different trapping efficiencies of self interstitial atoms by different impurities, which conditions different dimensions of depleted zones under equal parameters of irradiation have been investigated.