Abstract
Beryllium has been considered as a canning material for reactors of the EL 4 type (CO{sub 2} cooled, operating at 600 C). Two cases may be envisaged: either the can is not deformable under the exterior forces, but in this case a poor ductility may be tolerated, or else, the creep resistance is not sufficiently high; the ductility should then be high at operating temperatures and also at room temperature for thermal cycling. It became rapidly obvious that ordinary beryllium had not a sufficient creep resistance and it appeared difficult to increase it for EL 4 use (5 kg/mm{sup 2}). Other non-metallurgical factors also contributed to discard this approach. The second possibility was this considered and an attempt was made to increase the ductility of the metal which was for two low. The first objection was to determine to what extent this ductility depended on the purity. It is not yet possible to say whether the brittleness at ordinary temperatures is due to some low concentration of a particular impurity. In the purest beryllium, which can be obtained by distillation vacuum fusion zone melting or a combination of these methods the critical shear stress of the two possible slip modes
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Citation Formats
Weisz, M, and Mallen, J.
The use of beryllium as a canning material the problems arising from the brittleness of the metal and their present solution; L'utilisation du beryllium comme materiau de gaine les problemes poses par la fragilite du metal et leurs solutions actuelles.
France: N. p.,
1964.
Web.
Weisz, M, & Mallen, J.
The use of beryllium as a canning material the problems arising from the brittleness of the metal and their present solution; L'utilisation du beryllium comme materiau de gaine les problemes poses par la fragilite du metal et leurs solutions actuelles.
France.
Weisz, M, and Mallen, J.
1964.
"The use of beryllium as a canning material the problems arising from the brittleness of the metal and their present solution; L'utilisation du beryllium comme materiau de gaine les problemes poses par la fragilite du metal et leurs solutions actuelles."
France.
@misc{etde_20668333,
title = {The use of beryllium as a canning material the problems arising from the brittleness of the metal and their present solution; L'utilisation du beryllium comme materiau de gaine les problemes poses par la fragilite du metal et leurs solutions actuelles}
author = {Weisz, M, and Mallen, J}
abstractNote = {Beryllium has been considered as a canning material for reactors of the EL 4 type (CO{sub 2} cooled, operating at 600 C). Two cases may be envisaged: either the can is not deformable under the exterior forces, but in this case a poor ductility may be tolerated, or else, the creep resistance is not sufficiently high; the ductility should then be high at operating temperatures and also at room temperature for thermal cycling. It became rapidly obvious that ordinary beryllium had not a sufficient creep resistance and it appeared difficult to increase it for EL 4 use (5 kg/mm{sup 2}). Other non-metallurgical factors also contributed to discard this approach. The second possibility was this considered and an attempt was made to increase the ductility of the metal which was for two low. The first objection was to determine to what extent this ductility depended on the purity. It is not yet possible to say whether the brittleness at ordinary temperatures is due to some low concentration of a particular impurity. In the purest beryllium, which can be obtained by distillation vacuum fusion zone melting or a combination of these methods the critical shear stress of the two possible slip modes (0001) and (10 1-bar 0) along (11 2-bar 0) are even more different than in the less pure metal. This means that in the polycrystal, the grains which can deform are those which are favourably oriented for basal slip and the fracture mode is still a cleavage along a basal plane. Neither from a theoretical nor a practical point of view has purification led to a solution to the problem of room-temperature brittleness. The lack of ductility observed around 600 C is undoubtedly due to the presence of impurities and inclusions (oxides). The solution is to use cast metal of industrial purity (or thermally treated in order to modify the impurity distribution) and to eliminate sintering as a production process. Since, on the other hand, the intrinsic problem of the low-temperature brittleness was not solved, an attempt was made to overcome it by a stricter control of metallurgical factors. It has thus been possible to increase by a factor of 10 the low-temperature ductility of tubes (of commercial purity beryllium or even of corrosion-resisting alloys). This is sufficient for the present purpose. Experiments under way will show whether this is still true after exposure to significant irradiation doses. (authors) [French] Le beryllium est envisage comme materiau de gainage dans les reacteurs du type EL 4 (refroidi au gaz carbonique, temperature de fonctionnement 600 C). On peut considerer schematiquement deux cas: - soit la gaine est indeformable sous l'action des forces exterieures, mais on peut alors tolerer une faible ductilite; - soit la resistance au fluage n'est pas suffisante; la ductilite doit etre importante a chaud et egalement a froid pour la resistance au cyclage thermique. Il est apparu rapidement que le beryllium ordinaire avait une resistance au fluage trop faible et qu'il paraissait difficile de l'augmenter suffisamment pour EL 4 (5 kg/mm{sup 2}). D'autres facteurs non metallurgiques ont contribue egalement a l'abandon de cette voie de recherche. On s'est donc oriente vers la deuxieme possibilite en s'efforcant d'augmenter la ductilite du metal qui etait notablement insuffisante. On a d'abord cherche a determiner dans quelle mesure celle-ci dependait de la purete. Il n'est pas encore possible de decider si la fragilite a l'ambiante est due a la presence d'un faible taux d'une impurete particuliere. Dans le Beryllium le plus pur qu'il ait ete possible d'obtenir par distillation, fusion sous vide, fusion de zone ou la combinaison de ces procedes, les scissions critiques des deux modes de glissement possibles ((0001) et (10 1-bar 0)) suivant (11 2-bar 0) sont encore plus differentes que dans le metal moins pur. Ceci signifie que dans le polycristal les grains qui se deforment sont ceux qui peuvent le faire par glissement basal et le mode de rupture reste le clivage sur le plan de base. Du point de vue theorique comme du point de vue pratique la purification n'a pas apporte de solution au probleme de la fragilite a l'ambiante. Le manque de ductilite observe aux environs de 600 C est incontestablement du a la presence d'impuretes et aux inclusions (oxydes). La solution est d'utiliser du metal coule de purete industrielle (ou traite thermiquement afin de modifier la repartition des impuretes) et d'eviter le frittage comme procede d'elaboration. Par contre le probleme intrinseque de la fragilite a basse temperature n'etant pas resolu on a cherche a s'en accommoder par un controle plus strict des facteurs metallurgiques. On est parvenu ainsi a augmenter d'un facteur 10 la ductilite a basse temperature de tubes (de beryllium de purete commerciale ou meme d'alliages resistant a la corrosion). Ceci est suffisant pour l'utilisation envisagee. Des experiences en cours diront si ceci est encore vrai apres irradiation a des doses significatives. (auteurs)}
place = {France}
year = {1964}
month = {Jul}
}
title = {The use of beryllium as a canning material the problems arising from the brittleness of the metal and their present solution; L'utilisation du beryllium comme materiau de gaine les problemes poses par la fragilite du metal et leurs solutions actuelles}
author = {Weisz, M, and Mallen, J}
abstractNote = {Beryllium has been considered as a canning material for reactors of the EL 4 type (CO{sub 2} cooled, operating at 600 C). Two cases may be envisaged: either the can is not deformable under the exterior forces, but in this case a poor ductility may be tolerated, or else, the creep resistance is not sufficiently high; the ductility should then be high at operating temperatures and also at room temperature for thermal cycling. It became rapidly obvious that ordinary beryllium had not a sufficient creep resistance and it appeared difficult to increase it for EL 4 use (5 kg/mm{sup 2}). Other non-metallurgical factors also contributed to discard this approach. The second possibility was this considered and an attempt was made to increase the ductility of the metal which was for two low. The first objection was to determine to what extent this ductility depended on the purity. It is not yet possible to say whether the brittleness at ordinary temperatures is due to some low concentration of a particular impurity. In the purest beryllium, which can be obtained by distillation vacuum fusion zone melting or a combination of these methods the critical shear stress of the two possible slip modes (0001) and (10 1-bar 0) along (11 2-bar 0) are even more different than in the less pure metal. This means that in the polycrystal, the grains which can deform are those which are favourably oriented for basal slip and the fracture mode is still a cleavage along a basal plane. Neither from a theoretical nor a practical point of view has purification led to a solution to the problem of room-temperature brittleness. The lack of ductility observed around 600 C is undoubtedly due to the presence of impurities and inclusions (oxides). The solution is to use cast metal of industrial purity (or thermally treated in order to modify the impurity distribution) and to eliminate sintering as a production process. Since, on the other hand, the intrinsic problem of the low-temperature brittleness was not solved, an attempt was made to overcome it by a stricter control of metallurgical factors. It has thus been possible to increase by a factor of 10 the low-temperature ductility of tubes (of commercial purity beryllium or even of corrosion-resisting alloys). This is sufficient for the present purpose. Experiments under way will show whether this is still true after exposure to significant irradiation doses. (authors) [French] Le beryllium est envisage comme materiau de gainage dans les reacteurs du type EL 4 (refroidi au gaz carbonique, temperature de fonctionnement 600 C). On peut considerer schematiquement deux cas: - soit la gaine est indeformable sous l'action des forces exterieures, mais on peut alors tolerer une faible ductilite; - soit la resistance au fluage n'est pas suffisante; la ductilite doit etre importante a chaud et egalement a froid pour la resistance au cyclage thermique. Il est apparu rapidement que le beryllium ordinaire avait une resistance au fluage trop faible et qu'il paraissait difficile de l'augmenter suffisamment pour EL 4 (5 kg/mm{sup 2}). D'autres facteurs non metallurgiques ont contribue egalement a l'abandon de cette voie de recherche. On s'est donc oriente vers la deuxieme possibilite en s'efforcant d'augmenter la ductilite du metal qui etait notablement insuffisante. On a d'abord cherche a determiner dans quelle mesure celle-ci dependait de la purete. Il n'est pas encore possible de decider si la fragilite a l'ambiante est due a la presence d'un faible taux d'une impurete particuliere. Dans le Beryllium le plus pur qu'il ait ete possible d'obtenir par distillation, fusion sous vide, fusion de zone ou la combinaison de ces procedes, les scissions critiques des deux modes de glissement possibles ((0001) et (10 1-bar 0)) suivant (11 2-bar 0) sont encore plus differentes que dans le metal moins pur. Ceci signifie que dans le polycristal les grains qui se deforment sont ceux qui peuvent le faire par glissement basal et le mode de rupture reste le clivage sur le plan de base. Du point de vue theorique comme du point de vue pratique la purification n'a pas apporte de solution au probleme de la fragilite a l'ambiante. Le manque de ductilite observe aux environs de 600 C est incontestablement du a la presence d'impuretes et aux inclusions (oxydes). La solution est d'utiliser du metal coule de purete industrielle (ou traite thermiquement afin de modifier la repartition des impuretes) et d'eviter le frittage comme procede d'elaboration. Par contre le probleme intrinseque de la fragilite a basse temperature n'etant pas resolu on a cherche a s'en accommoder par un controle plus strict des facteurs metallurgiques. On est parvenu ainsi a augmenter d'un facteur 10 la ductilite a basse temperature de tubes (de beryllium de purete commerciale ou meme d'alliages resistant a la corrosion). Ceci est suffisant pour l'utilisation envisagee. Des experiences en cours diront si ceci est encore vrai apres irradiation a des doses significatives. (auteurs)}
place = {France}
year = {1964}
month = {Jul}
}