Computersimulationen und Experimente zur Entwicklung von Heliumblasen in Metallen

Zell, V.

Book/Report

FZJ-2018-06401

Computersimulationen und Experimente zur Entwicklung von Heliumblasen in Metallen

Zell, V. (Corresponding author)FZJ*

1994
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Berichte des Forschungszentrums Jülich 2873, II, 92 p. (1994)

Please use a persistent id in citations: http://hdl.handle.net/2128/20020

Report No.: Juel-2873

Abstract: In this work, the evolution of inert gas bubble microstructures in metals by migration and coalescence has been studied by a simulation approach for two typicalexperimental conditions: (A) Coarsening at constant gas content during annealing after low temperature implantation and (B) bubble evolution under continuous gasproduction at elevated temperatures. For the latter case also experiments in which Helium was implanted into Nickel were performed with particular emphasis on thetemperature and production rate dependence of bubble size and density. The simulation shows that the bubble size distributions in case (A) become asymptotically selfsimilar, whereas under (B) there is no simple scaling behaviour. The time dependence of the mean bubble radius and the bubble density in case (A) follow simple power laws. While the bubble densities in (A) are always decreasing with increasing time, in case (B) the bubble density generally saturates or even increases, depending on the gas state in the bubbles and the assumption about the migration mechanism. The measured bubble densities and mean radii in the experiment show Arrhenius behaviour in a low temperature regime with a low apparent activation energy and in a high temperature regime with a high apparent activation energy. The data indicate that the low temperature regime is controlled by He diffusion via the self-interstitial/He replacement mechanism and the high temperature regime is He dissociation controlled according to standard nucleation models. Also the rate dependence confirm these findings. Effects of bubble migration and coalescence could not be identified. The bubbles are considered to be in an overpressurized state. The results are compared with data obtained from Nickel in the case of an experiment of type (A) and with data from stainless steel.

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