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Comparative study of the creep behaviour of single crystals and polycrystals of alpha uranium; Etude comparee du comportement au fluage de l'uranium alpha mono et polycristallin

Abstract

In the first chapter, one describes the creep machine developed to study the deformation of uranium at high temperature in vacuum with a continuous recording. The second chapter presents the results concerning the polycrystals of uranium. The application of the DORN method gives an activation energy for creep of 42 {+-} 2 Kc, above 550 Celsius degrees, equal to the activation energy for self-diffusion. The study of the variation of the creep rate with the applied stress and the metallographic observations of the deformation induced polygonization allow to conclude that the deformation is controlled by climb of dislocations. In the third chapter, the deformation above 550 Celsius degrees of single crystals of uranium (obtained by {beta} {yields} {alpha} change) is studied. The major deformation mode is slip. The preexisting polygonization of these single crystals is very stable and the disorientation between adjacent sub-grains increases with the deformation. The activation energy for creep is higher than that for polycrystals. These results show the influence of the polygonization due to the {beta} {yields} {alpha} change on the creep behaviour of {alpha} uranium. (authors) [French] Dans le premier chapitre, on decrit la machine de fluage sous vide a enregistrement continu, mise au point  More>>
Authors:
Andre, J P [1] 
  1. Commissariat a l'Energie Atomique, Saclay (France). Centre d'Etudes Nucleaires
Publication Date:
Mar 01, 1964
Product Type:
Thesis/Dissertation
Report Number:
CEA-R-2715
Resource Relation:
Other Information: TH: These sciences; 7 refs
Subject:
36 MATERIALS SCIENCE; ACTIVATION ENERGY; CREEP; MICROSTRUCTURE; POLYCRYSTALS; URANIUM
OSTI ID:
20680215
Research Organizations:
CEA Saclay, 91 - Gif-sur-Yvette (France); Faculte des Sciences de l'Universite de Paris, 75 (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR05R2715115105
Availability:
Available from INIS in electronic form
Submitting Site:
FRN
Size:
[40] pages
Announcement Date:
Jan 07, 2006

Citation Formats

Andre, J P. Comparative study of the creep behaviour of single crystals and polycrystals of alpha uranium; Etude comparee du comportement au fluage de l'uranium alpha mono et polycristallin. France: N. p., 1964. Web.
Andre, J P. Comparative study of the creep behaviour of single crystals and polycrystals of alpha uranium; Etude comparee du comportement au fluage de l'uranium alpha mono et polycristallin. France.
Andre, J P. 1964. "Comparative study of the creep behaviour of single crystals and polycrystals of alpha uranium; Etude comparee du comportement au fluage de l'uranium alpha mono et polycristallin." France.
@misc{etde_20680215,
title = {Comparative study of the creep behaviour of single crystals and polycrystals of alpha uranium; Etude comparee du comportement au fluage de l'uranium alpha mono et polycristallin}
author = {Andre, J P}
abstractNote = {In the first chapter, one describes the creep machine developed to study the deformation of uranium at high temperature in vacuum with a continuous recording. The second chapter presents the results concerning the polycrystals of uranium. The application of the DORN method gives an activation energy for creep of 42 {+-} 2 Kc, above 550 Celsius degrees, equal to the activation energy for self-diffusion. The study of the variation of the creep rate with the applied stress and the metallographic observations of the deformation induced polygonization allow to conclude that the deformation is controlled by climb of dislocations. In the third chapter, the deformation above 550 Celsius degrees of single crystals of uranium (obtained by {beta} {yields} {alpha} change) is studied. The major deformation mode is slip. The preexisting polygonization of these single crystals is very stable and the disorientation between adjacent sub-grains increases with the deformation. The activation energy for creep is higher than that for polycrystals. These results show the influence of the polygonization due to the {beta} {yields} {alpha} change on the creep behaviour of {alpha} uranium. (authors) [French] Dans le premier chapitre, on decrit la machine de fluage sous vide a enregistrement continu, mise au point pour etudier le phenomene. Le deuxieme chapitre presente les resultats relatifs aux polycristaux. L'utilisation de la methode de DORN a permis de constater que, au-dessus de 550 degres Celsius, l'energie d'activation pour le fluage avait une valeur constante egale a 42 {+-} 2 Kc, voisine de la chaleur d'autodiffusion. L'etude de l'influence de la contrainte appliquee sur la vitesse de fluage et l'observation micrographique de la polygonisation developpee au cours de la deformation permettent de conclure que le phenomene est controle par la montee des dislocations. Dans le troisieme chapitre, on etudie le comportement au fluage au-dessus de 550 C des monocristaux obtenus par changement de phase a l'etat solide. La deformation s'effectue essentiellement par glissement. La polygonisation inherente a l'obtention de ces monocristaux est extremement stable et la desorientation entre sous-grains augmente avec la deformation. La valeur de l'energie d'activation pour le fluage est superieure a celle des polycristaux. Ces resultats montrent l'influence de la polygonisation introduite par le passage de la phase beta a la phase alpha sur le comportement au fluage de l'uranium alpha.}
place = {France}
year = {1964}
month = {Mar}
}