Effect of various components of slightly diluted tungsten-based alloys on the formation of defects in atomic displacement cascade regions: Field-ion microscopic analysis

Abstract

New complex field-ion microscopic data for the formation of radiation-induced defects in VChV ultrapure tungsten, VA-3 commercial-grade tungsten, and four slightly diluted tungsten-based alloys (W-Hf-C, P39A; W-1.5% ThO2, VT-15; W-5% Re, VR-5; and W-2% Fe, VZh-2) are reported. Samples were irradiated in an external unit by Ar+ and Ni+ ions of energy 35 keV. In the experiments, the ion current is kept at j=2.0 µA and the irradiation fluence equals Φt=5×1014 ions/cm2. The clustering of single vacancies in samples irradiated is studied in relation to the impurity concentration and type. The distribution of vacancy clusters over the number of aggregated single vacancies is studied. These distributions are found to differ noticeably inside and outside the depletion zones. The mean lengths of focused substitutional atomic collision chains in samples with different impurity concentrations and types are measured indirectly. From these data, the efficiency of trapping intrinsic interstitials by various impurities in tungsten is estimated.