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High temperature strain behavior of Zircaloy-4 and Zr--2. 5Nb fuel sheaths

Journal Article · · Am. Soc. Test. Mater., Spec. Tech. Publ.; (United States)
OSTI ID:6301841

The ballooning behavior of Zircaloy-4 fuel sheaths at high temperatures was reported previously by Hardy. Similar tests were done on Zr--2.5Nb tubes. In both materials, the importance of the phase transformation from hexagonal close-packed to body-centered-cubic structure is evident. Towards the upper boundary of the two-phase (..cap alpha.. + ..beta..) region where ..beta..-phase material would dominate, there is a marked discontinuity in the strain versus temperature results. They indicate that the solid solution strengthening in the ..beta..-phase is more effective than the second phase particle strenghtening in the ..cap alpha..-phase. At normal operating temperatures, Zr--2.5Nb is stronger than Zircaloy-4. However, above 600/sup 0/C it enters the two-phase temperature region and becomes weaker than Zircaloy-4 which is still within the ..cap alpha..-phase. In the ..beta..-phase, where Zr--2.5Nb contains about twice as many atoms in solid solution as Zircaloy-4, the former again becomes stronger. At 1000/sup 0/C, the strain rate of Zr--2.5Nb is about two orders of magnitude less than that of Zircaloy-4 at the same stress.

Research Organization:
Atomic Energy of Canada Ltd., Chalk River, Ontario
OSTI ID:
6301841
Journal Information:
Am. Soc. Test. Mater., Spec. Tech. Publ.; (United States), Journal Name: Am. Soc. Test. Mater., Spec. Tech. Publ.; (United States) Vol. 633; ISSN ASTTA
Country of Publication:
United States
Language:
English