Quantitative analysis of void swelling in pure copper

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Abstract
This paper presents a quantitative analysis of void swelling experiments in pure copper irradiated in a high voltage electron microscope (HVM). Both dislocation loop growth and void growth were measured over the temperature range 140–320°C. The simultaneous measurement of these growth rates allows both the vacancy migration energy, E, v, and the dislocation bias to be unambiguously determined and the analysis can also distinguish the void sink strength from the other parameters involved. It was found that void growth cannot be adequately described simply with the assumption of random diffusion of point defects to the sink and we choose to describe the growth successfully with initial control by defect transfer across the void interface. Alternative descriptions may be possible. The analysis was performed numerically using the Rate Theory Continuum (RTC) model with suitable modifications to include the influence of defect recombination on the various sink strengths. Such modifications are made necessary by the choice of the type of irradiation employed, i.e. high-flux irradiation in the HVM. The emphasis throughout has been to use a model that is directly applicable to bulk metals under neutron irradiation. For this reason also, the foil surfaces have been represented as a continuum sink for defects. We find from the analysis that JSm v≍0·77 eV with an interstitial volume ΔVI ≍0·6 Ω corresponding to a dislocation bias of 6–7%. This paper presents a quantitative analysis of void swelling experiments in pure copper irradiated in a high voltage electron microscope (HVM). Both dislocation loop growth and void growth were measured over the temperature range 140–320°C. The simultaneous measurement of these growth rates allows both the vacancy migration energy, Em v , and the dislocation bias to be unambiguously determined and the analysis can also distinguish the void sink strength from the other parameters involved. It was found that void growth cannot be adequately described simply with the assumption of random diffusion of point defects to the sink and we choose to describe the growth successfully with initial control by defect transfer across the void interface. Alternative descriptions may be possible.