Precipitation in Zr-2.5Nb during 10 MeV electron irradiation
- AECL Research, Chalk River, Ontario (Canada). Chalk River Labs.
The corrosion resistance of Zr-2.5Nb is increased by neutron irradiation at 570K. This is due to the radiation-enhanced precipitation of {beta}-Nb within the {alpha}-Zr grains, and the associated reduction in the Nb concentration in the {alpha}-Zr matrix during irradiation. This microstructure was observed in annealed Zr-2.5Nb irradiated with neutrons at 670K and 770K, and also with protons between 770 and 720 K to 0.9 dpa. In this study, the samples annealed Zr-2.5Nb, in the form of four 8 mm diameter, 0.5 mm thick discs, was irradiated with 10 MeV electrons for 370 hours. The damage accumulated on the discs ranged from 0.5 10 1.2 dpa, while the temperature of each disc varied from 720K at the center to 600K at the edge. TEM examination of the 1.2 dpa, 710K sample revealed needle-like precipitates in the {alpha}-Zr matrix. These precipitates, having widths of 1 or 2 nm and lengths up to 70 nm, were shown by EDX analysis to contain Zr and Nb. Dark field observations using a precipitate reflection confirmed that the precipitates were {beta}-Nb with about 88% Nb. Specimens made form the same Zr-2.5Nb that were annealed at 720K for 370 hours but unirradiated had clear {alpha}-Zr grain interiors, with no precipitates. Thus electron irradiation produced a microstructure similar to that produced by neutrons and protons.
- OSTI ID:
- 99437
- Report Number(s):
- CONF-941144--; ISBN 1-55899-275-8
- Country of Publication:
- United States
- Language:
- English
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