Blistering and Helium Retention of Tungsten and 5% Chromium Doped Tungsten Exposed to 60 keV Helium Ions Irradiation☆☆Supported by the National Natural Science Foundation of China under Grant Nos 51471015 and 11675010, and the National Magnetic Confinement Fusion Program under Grant No 2015GB109003.

Abstract

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.