THE URANIUM-RHENIUM ALLOY SYSTEM
The phase diagram of the uranium- rhenium alloy system is presented along with a discussion on transformation kinetics of the uranium solid solutions. The phase diagram is of the double eutectic type with the intermediate phase having the composition URe/sub 2/. This phase exhibits allotropy at 180 deg C and melts congruently at 2200 deg C. URe/sub 2/ reacts sluggishly with the uranium solid solutions below 750 deg C to form the peritectoid compound U/sub 2/ Re. Eutectic reactions occur at 1105 and 2105 deg C at respective compositions of 10.5 and 65.5 wt% Re. Eutectoid reactions occur at 643 and 681 deg C at conrpositions of 1.4 and 6 wt% Re, respectively. The maximum solubility of rhenium in alpha uranium is about 0.4 wt% at 643 deg C and in BETA uranium is 1.9 wt% at 681 deg C. The solubility of rhenium in gamma uranium is 6 wt% at 68l deg C and increases to about 7 wt% at 975 deg C. The solubility of uranium in rhenium is 0.6 wt% at room temperature with little variation up to 2000 deg C. Alloys of BETA and gamma uranium containing more than about 1.2 and 7 wt% Re respectively, can be readily supercooled to room temperature. Rapid cooling of gamma alloys containing less than about 7 wt% Re resulted in a direct gamma -- alpha ' transformation, the alpha ' state being a supersaturated alpha phase having a banded microstructure. Evidence is presented for the existence of two transition states, one involving the gamma phase decomposition and the other the BETA yields alpha transformation. The sequence of phase changes involved in cooling the uranium solid solutions is discussed. (auth)
- Research Organization:
- Ames Lab., Ames, Iowa
- NSA Number:
- NSA-18-008834
- OSTI ID:
- 4093338
- Journal Information:
- J. Less-Common Metals, Journal Name: J. Less-Common Metals Vol. Vol: 5
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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