L.J. Nowicki

Effects of neutron irradiation and hydrogen on ductile-brittle transition temperatures of V-Cr-Ti alloys

The effects of neutron irradiation and hydrogen on the ductile- brittle transition temperatures (DBTTs) of unalloyed vanadium and V-Cr-Ti alloys were determined from Charpy-impact tests on 1/3 ASTM standard size specimens and from impact tests on 3-mm diameter discs. The tests were conducted on specimens containing <30 appm hydrogen and 600-1200 appm hydrogen and on specimens after neutron irradiation to 28-46 dpa at 420, 520, and 600C. The DBTTs were minimum (< {minus}220{degree}C) for V-(105)Ti alloys under for V-4-Cr-4Ti alloy with <30 appm hydrogen. The effect of 600-1200 appm hydrogen in the specimens was to raise the DBTTs by 100--150{degree}C. The DBTTs were minimum (< {minus}220{degree}C) for V-(1-5)Ti alloys and V-4-Cr-4Ti alloys after neutron irradiation.

Tensile and impact properties of V–4Cr–4Ti alloy heats 832665 and 832864 ☆

Abstract Two large heats of V–4Cr–4Ti alloy were produced in the US in the past few years. The first, 832665, was a 500 kg heat procured by the US Department of Energy for basic fusion structural materials research. The second, 832864, was a 1300 kg heat procured by General Atomics for the DIII-D radiative divertor upgrade. Both heats were produced by Oremet-Wah Chang (previously Teledyne Wah Chang of Albany). Tensile properties up to 800°C and Charpy V-notch impact properties down to liquid nitrogen temperature were measured for both heats. The product forms tested for both heats were rolled sheets annealed at 1000°C for 1 h in vacuum. Testing results show the behavior of the two heats to be similar and the reduction of strengths with temperature to be insignificant up to at least 750°C. Ductility of both materials is good in the test temperature range. Impact properties for both heats are excellent – no brittle failures at temperatures above −150°C. Compared to the data for previous smaller laboratory heats of 15–50 kg, the results show that scale-up of vanadium alloy ingot production to sizes useful for reactor blanket design can be successfully achieved as long as reasonable process control is implemented (H. Tsai, et al., Fusion Materials Semiannual Progress Report for Period Ending 30th June 1998, DOE/ER-0313/24, p. 3; H. Tsai, et al., Fusion Materials Semiannual Progress Report for Period Ending 31st December 1998, DOE/ER-0313/25, p. 3).

Effects of proton bombardment on self-diffusion in silver: A preliminary report☆

Abstract The radiation-enhanced self-diffusion coefficient D rad in silver under 270 keV proton bombardment has been measured over the temperature range from 240° to -60 °C. The flux dependence of D rad has also been studied at 106° and 179 °C with the flux varying from 2.5 × 10 12 to 6.3 × 10 13 protons/cm 2 sec. The experimental data are analyzed in the framework of the classical model involving single vacancies and interstitials as mobile defects.

Effect of neutron irradiation on tensile properties of V-Cr-Ti alloys

Abstract The tensile properties of V-4Cr-4Ti, V-9Cr-5Ti, V-14Cr-5Ti, V-3Ti-1Si, V-5Ti, and V-18Ti alloys were determined at 25, 420, 520, and 600°C after neutron irradiation to 28–46 dpa at 420, 520, and 600°C. The yield strength of the unirradiated alloys increased significantly (~ 50%) upon neutron irradiation. Irradiation hardening of the alloys at 25°C after irradiation at 420°C was in the order of V-18Ti