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AbstractAbstract
[en] Through the measurements in Transmission Electron Microscopy and Microhardness is studied the effect of fast neutron irradiation (E > or = 0,1 MeV) on the Recovery and Recrystallization in very pure grade Niobium. The range of temperature is 250C - 12000C for one hour. The sigmoidal curve of the Recovery in Niobium shows a initial increase in the microhardness in the range of temperature of 250C - 3000C, who is related to the intersticial migration (impurity atoms) O, C and N to the dislocations and to the defects clusters produced by cold work and radiation. The Recrystallization in cold worked Niobium comes by subgrain growth (subgrains coalescence) and by strain induced grain boundary migration. The radiation with fast neutrons (O=1,3 x 1018 nvt) acelerates the overall nucleation process of Recrystallization by about 1500C with respect to the only deformed Niobium. The activation energy for the Recrystallization process is obtained in both cases, in the rolling Niobium and in Nb deformed and irradiated by fast neutrons (1,2 x 1017 nvt)
[pt]
Estuda-se atraves de medidas efetuadas em Microscopia Eletronica de Transmissao e Microdureza o efeito da irradiacao neutronica (E > ou = 0,1 MeV) na Recuperacao e Recristalizacao de Niobio de alta pureza. O intervalo de temperatura e de 250C ate 12000C por uma hora. A curva sigmoidal da Recuperacao no Niobio mostra um aumento inicial na microdureza no intervalo de temperatura de 25 e 3000C, que esta relacionado a migracao de intersticiais (atomos de impurezas), O, C e N para as discordancias e aglomerados de defeitos produzidos por laminacao e irradiacao. A Recristalizacao no Niobio laminado se processa por crescimento de subgrao (coalescimento de subgraos) e migracao de contorno de grao induzido por deformacao. Irradiacao com neutrons rapidos (0=1,3 x 1018 nvt) acelera todo o processo de nucleacao da recristalizacao de 1500C em relacao ao Niobio nao irradiado. Obtem-se tambem a energia de ativacao para o processo de Recristalizacao do Niobio tanto no caso do Niobio laminado como tambem no Niobio laminado e irradiado (1,2 x 1017 nvt)Original Title
Efeito da radiacao neutronica na recuperacao e recristalizacao do niobio policristalino
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IEA Dissertacao e Tese; no. 081; Sep 1978; 71 p; Tese (M.Sc.).
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