Quarterly progress report, Metallurgy Research sub-section, April 1955--June 1955

One uranium tensile specimen irradiated to 620 MWD/T (1.75 x 10{sup 20} nvt) was tested at 285 C (545 F). The values obtained were: ultimate tensile strength 71,000 psi, 0.1% offset yield strength 70,000 psi, percent elongation (one inch gage length) 0.7, and modulus of elasticity 12 x 10{sup 6}. These values are comparable to the as-irradiated values of specimens tested at room temperature which were: ultimate tensile strength 76,000 psi, 0.1% offset yield strength 71,500 psi, and percent elongation (one inch gage length) 0.36. The elongation of the specimen tested at 285 C was less than that of a specimen annealed at 700 C (1290 F) after irradiation, then tested at room temperature. Experiments have been initiated to determine the structural stability of irradiated uranium-silicon alloy when this alloy is in the stable epsilon phase. Present work is limited to the evaluation of thermal expansion as a criterion for degree of epsilonization. This technique has not proven satisfactory. The damage resulting from the bombardment of uranium with electrons in the 1-2 MEV range is to be evaluated using electrical resistivity and x-ray diffraction to determine the extent of the damage. Calculations indicate a threshold energy of about 1.25 MEV electrons is necessary to generate vacancy-interstitial pairs