Comment on "Free Migration of Interstitials in Tungsten"

We briefly summarize the results of an extensive series of recent field-ion microscope experiments on ion-irradiated (20- and 30-keV ${\mathrm{W}}^{+}$) tungsten (with residual resistance ratios varying from 5 × ${10}^4$ to 5), tungsten specifically doped with carbon, and tungsten-0.5-at.%- and - 3-at.%-rhenium alloys. The field-ion microscope experiments are all consistent with the long-range migration of a self-interstitial atom occuring at ∼38 This result is contrasted to the recent conclusions of Okuda and Mizubayashi.