Investigation of pulsed irradiation effects on interstitial loop growth in metals

The creep of nickel under pulsed electron irradiation

“…Since in the low-temperature range the activation volume is almost independent of temperature, one may assume that temperature variations of the creep mechanism, revealed as the change in the apparent activation energy, are related neither to the type of dislocations nor to the character and distribution of the obstacles to their motion. The apparent activation energy is observed to decrease monotonically from the value characteristic of lattice self-diffusion (66.8 kcal mol-', Wazzan and Dorn (1965)) down to that typical of dislocation pipe-diffusion (26.7 kcal mol-', Gertsriken and Yatsenko (1961); 32.3 kcal mol-', Wazzam and Dorn (1965)) when lowering temperature below 300°C. This thereby confirms a decrease in the contribution of lattice self-diffusion and an increase of that of dislocation pipe-diffusion within the same diffusion-controlled mechanism of strain.…”

“…How the material structure behaves under pulsed irradiation has received particular attention (Nair, Sahu and Krishan 1982). The unsteady mode of irradiation can have a considerable effect on the processes of void growth and swelling of materials, as was shown by Loomis and Gerber (1982) for a variable irradiation temperature or by Volubuev, Gann, Bereznyak and Kirjukhin (1980) for pulsed irradiation at a constant temperature. Vnsteady irradiation seems, however, to affect most of all the character and intensity of the processes of radiation-induced creep.…”