PRECIPITATION OF HELIUM IN BERYLLIA IRRADIATED BY NEUTRONS (in French)
Electron microscopic examinations were made of irradiated and non- irradiated BeO samples before and after thermal treatment. In the non-irradiated samples the average dimension of the crystals is 10 to 20 microns, and the majority of the facets are hidden with stria. After thermal treatment the beryllium oxide presents no bubbles. In the irradiated beryllia, the crystals have the same dimensions but smooth facets are more numerous. Thermal treatment for 24 hr at 800 deg C causes no visible change. After a second thermal treatment at 1000 deg C the samples have two kinds of bubbles, closely packed bubbles with a diameter of several hundred angstroms and some bubbles five to ten times larger with a polyhedral form. A third annealing at 1200 deg C results in elongated bubbles of several microns on the smooth facets which delineate the crystal. An annealing at 1500 deg C accentuates the collection of the bubbles into polyhedral cavities of the order of several tens of microns. The results show that the neutroninduced gas Precipitates in the mass of the sample and then the bubbles migrate toward the surface of the grain boundaries. (J.S.R.)
- Research Organization:
- Service de Chimie des Solides, Saclay, France
- NSA Number:
- NSA-13-015412
- OSTI ID:
- 4240595
- Journal Information:
- J. Nuclear Materials, Journal Name: J. Nuclear Materials Vol. Vol: 1
- Country of Publication:
- Country unknown/Code not available
- Language:
- French
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