Effect of liquid uranium on tungsten foils up to 1350°C

Abstract

Immersion experiments have been performed to investigate the effect of liquid uranium on 0.3-mm-thick foils of tungsten metal in the temperature range of 1160 to 1350°C, for immersion times up to 20 h, in zirconia crucibles. The original and uranium-reacted foils have been studied microscopically (SEM-EDAX) and the internal morphology has been determined. The latter is affected by the heat-treatment and penetration of liquid uranium. The penetration is partial up to 1210°C, accompanied by a partial uranium-assisted recrystallization, forming two metallurgically-different regions, which on cooling result in the observed cracks due to inhomogeneous strain. The penetration of liquid uranium is complete at 1255°C and above, inducing recrystallization of tungsten grains throughout the foil, with larger, uranium-lined, grains in inner regions, and smaller, progressively-separated, tungsten grains in outer regions (with reduction in foil thickness).