Comment on "Free Migration of Interstitials in Tungsten"

Results are briefly summarized of an extensive series of recent field- ion microscope experiments on ion-irradiated (20-and 30-keV W$sup +$) tungsten (with residual resistance ratios varying from 5 x 10$sup 4$ to 5), tungsten specifically doped with carbon, and tungsten--0.5-at. percent- and 3-at. percent- rhenium alloys. The experiments are all consistent with the long-range migration of a self-interstitial atom occurring at approximately 38$sup 0$K. This result is contrasted to the recent conclusions of Okuda and Mizubayashi.