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Title: Positron annihilation study of electron-irradiated FeCu and FeCuC alloys

Journal Article · · Scripta Metallurgica et Materialia; (United States)

This study is mainly aimed at understanding the fundamental process of the irradiation embrittlement observed in low alloy reactor pressure vessel (RPV) steels used under neutron irradiation environments. For this purpose it has been recognized that the microstructural mechanism of the interaction between radiation-induced defects and some special minor element atoms in ferritic steels and the recovery process of the defect-impurity clusters must be fully investigated. In particular, attention has been focused on the role of copper, which is one of the minor elements in these steels, and many studies have been performed. It is known that in the ferrite matrix a copper atom has a large size factor, namely, 17.53% and the solubility limit is very low, especially at low temperatures. These facts suggest that copper atoms might form precipitates in the irradiated specimens with the help of radiation induced defects, especially vacancies. In the actual steels more complicated precipitates, which consist of copper, carbon and other impurity atoms, might be formed, in the presence of radiation defects, and again play a role in the trapping of vacancies and self-interstitial atoms (SIAs). In this situation positron annihilation measurements are a powerful technique, yielding atomic scale information, especially on very small vacancy type defects, incoherent precipitates and others, which are beyond the resolution limit of the electron microscopy. In the present study, therefore, positron annihilation lifetime measurements have been carried out for Fe-Cu and Fe-Cu-C alloy specimens of various concentrations by means of electron irradiation at 77K in order to clarify the fundamental process of the interaction between copper, carbon and vacancies.

OSTI ID:
6470374
Journal Information:
Scripta Metallurgica et Materialia; (United States), Vol. 29:2; ISSN 0956-716X
Country of Publication:
United States
Language:
English