Thermal Cycling Behavior and Thermal Stability of Uranium-Molybdenum Alloys of Low Molybdenum Content; COMPORTEMENT AU CYCLAGE THERMIQUE ET STABILITE THERMIQUE DES ALLIAGES URANIUM-MOLYBDENE DE FAIBLES TENEURS EN MOLYBDENE
A study was made of the behavior during thermal cycling of as-cast U--Mo alloys whose molybdenum content varies from 0.5 to 3 per cent; results are given concerning grain stability during extended heat treatments and the effect of treatments combining protracted heating with thermal cycling. The thermal cycling treatments were carried out at 550, 575, 600, and 625 deg C for 1000 cycles; the protracted heating experiments were done at 550, 575, 600, and 625 deg C for 2000 hours (4000 hr at 625 deg C). The 0.5 per cent alloy resists much better to the thermal cycling than does the non-alloyed uranium. This resistance is, however, much lower than that of alloys containing over 1 per cent, even at 550 deg C; it improves after a heat treatment for grain refining. Alloys of over 1.1 per cent have a very good resistance to a cycling treatment even at 625 deg C, and this behavior improves with increasing concentrations up to 3 per cent. An increase in the temperature up to the BETA phase has few disadvantages provided that it is followed by rapid cooling (50 to 100 deg C/min). The alpha grain is fine, the gamma phase is of the modular form, and the behavior during a thermal cycling treatment is satisfactory. If this cooling is slow (15 deg / hr) the alpha grain is coarse and cycling treatment behavior is identical to that of the 0.5 per cent alloy. The protracted heat treatments showed that the alpha grain exhibits satisfactory stability after 2000 hours at 575, 600 and 625 deg C, and after 4000 hours at 625 deg C. A heat cycling treatment carried out after these tests affects only very little the behavior of these alloys during cycling. (auth)
- Research Organization:
- France. Commissariat a l'Energie Atomique. Centre d'Etudes Nucleaires, Saclay
- NSA Number:
- NSA-18-000598
- OSTI ID:
- 4157841
- Report Number(s):
- CEA-2289
- Country of Publication:
- France
- Language:
- English
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