SWELLING OF URANIUM AND URANIUM ALLOYS ON POSTIRRADIATION ANNEALING
The swelling of U and of a few selected U alloys on postirradiation annealing was investigated by utilizing density measurements in conjunction with the observation of pores in the microstructures of annealed specimens. Speciniens were irradiated to about 0.3 at.% burnup in a constrained condition at approximately 275 deg C and were subsequently pulse annealed. The amount of swelling was found to be less than 1% for U specimens that were pulse annealed up to 75 hr at temperatures below 550 deg C; the amount of swelling, however, increased considerably on annealing at temperatures between 550 and 650 deg C. Specimens pulse annealed up to 75 hr at 618 deg C decreased in density by approximately 18%. The swelling was accompanied by the formation of bubbles on grain boundaries in recrystallized regions. The observations suggest that recrystallization is a necessary prerequisite for pronounced swelling in the alpha phase. Uranium specimens pulse annealed up to 75 hr at temperatures between 650 and 750 deg C in the BETA phase decreased in density by about 5%. Specimens annealed in the BETA phase, in contrast with those annealed at 618 deg C in the alpha phase, were badly cracked and contained pores of a smaller diameter, which were uniformly distributed within the grains. A specimen pulse annealed up to 16 hr at 822 deg C decreased in density, by, about 20%. This heat treatment produced pores of large diameter, located along grain boundaries, as well as pores of smaller diameter, distributed uniformly within the grains. Uranium alloys containing between 1 wt% and 9 wt% of either Ti, Zr, Nb, or Mo generally swelled more than pure U on pulse annealing up to 75 hr at 618 deg C and 740 deg C. An exception was the behavior of a U --4.0 wt % Nb alloy, which swelled less than U on annnealing at 618 deg C. A C addition of 0.11 wt% to U substantially decreased the swelling on pulse annealing up to 75 hr at 618 deg C, whereas the effect of 0.02 wt % N was small; at 740 deg C a N addition of 0.02 wt % to U caused an appreciable increase in the swelling, but the effect of 0.11 wt % C was slight. (auth)
- Research Organization:
- Argonne National Lab., Ill.
- DOE Contract Number:
- W-31109-ENG-38
- NSA Number:
- NSA-17-006737
- OSTI ID:
- 4749949
- Report Number(s):
- ANL-6532
- Country of Publication:
- United States
- Language:
- English
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ALLOTROPY
ANNEALING
BUBBLES
CARBIDES
CRACKS
DENSITY
EXPANSION
GRAIN BOUNDARIES
MEASURED VALUES
METALLOGRAPHY
METALS, CERAMICS, AND OTHER MATERIALS
MOLYBDENUM ALLOYS
NIOBIUM ALLOYS
NITRIDES
PHASE DIAGRAMS
POROSITY
PULSES
RADIATION EFFECTS
RECRYSTALLIZATION
TEMPERATURE
TITANIUM ALLOYS
URANIUM
URANIUM ALLOYS
ZIRCONIUM ALLOYS