Blistering and Helium Retention of Tungsten and 5% Chromium Doped Tungsten Exposed to 60 keV Helium Ions Irradiation.

Pure tungsten (W) and chromium doped W (W-5%Cr) are prepared by powder metallurgy. The microstructure, blistering and helium retention are investigated by x-ray diffraction, scanning electron microscopy, transmission electron microscopy and thermal desorption spectroscopy (TDS). These results show that the average size and density of helium blisters on the surface of pure W are much larger than those on the W-5%Cr alloy. Vacancy-impurity pairs can reduce the migration coefficients of vacancy and vacancy-helium complexes, and Cr may play a role of such an impurity. Moreover, the TDS result shows that the highest desorption peak moves to higher temperature, which is attributed to the HemCrkVn complexes in the W-Cr alloy. In addition, the helium retention is found to be higher in W than in W-5%Cr. [ABSTRACT FROM AUTHOR]