Сharacteristics of the creep and evolution of the structure in niobium in the temperature range 77…300 К

• Main Authors: Karaseva, Е.V., Mats, А.V., Sokolenko, V.I.
• Format: Article
• Language: English
• Published: Національний науковий центр «Харківський фізико-технічний інститут» НАН України 2018
• Series: Вопросы атомной науки и техники
• Subjects: Материалы реакторов на тепловых и быстрых нейтронах
• Online Access: http://dspace.nbuv.gov.ua/handle/123456789/147244

The changes in the structure, resistivity and plastic deformation characteristics of the polycrystalline niobium, annealed and also preliminary deformed by drawing to 80%, were studied at 77 and 300 K. It is shown that during the low-temperature creep of highly defect systems, the dislocation exhaustion mechanism is working even at stresses above the yield stress as the processes of linear defect generation under these conditions are strongly hindered. The development of low-temperature creep processes in the highly distorted fragmented structures cannot be described by the classical representations. A transition from the logarithmic creep to the power law creep, characteristic for much higher temperatures is observed, at the same time the total level of internal stresses being decreased. The variation of the law of plastic flow in the given stage of niobium creep at low temperatures does not depend on the method of highly distorted structure formation. The formation of new structures, which are steadier to tensile stresses, plays a determining role.