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Phase Relations in the System Uranium—Nitrogen
Author(s) -
BUGL J.,
BAUER A. A.
Publication year - 1964
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1964.tb14429.x
Subject(s) - uranium , nitrogen , crucible (geodemography) , phase diagram , solubility , decomposition , liquid nitrogen , chemistry , melting point , analytical chemistry (journal) , quenching (fluorescence) , phase (matter) , thermodynamics , mineralogy , materials science , metallurgy , organic chemistry , computational chemistry , physics , quantum mechanics , fluorescence
To supplement efforts to develop UN as a nuclear fuel material, a study of the phase relations in the system uranium‐nitrogen was conducted. The decomposition behavior and melting point of UN was studied in a controlled nitrogen‐pressure apparatus in which cast specimens of UN were heated and observed. UN decomposed at pressures of nitrogen below 2.5 atm at temperatures below 2850° C and melted congruently at 2850° C and pressures of 2.5 atm or greater. The nitrogen content of the liquid uranium phase in equilibrium with UN was determined by heating uranium in a UN crucible and then quenching and analyzing the equilibrated phase. The solubility of nitrogen in atomic percent can be expressed as S = 2.45 × 10 4 exp (‐38,800/RT) for temperatures in OK. Studies in the region U 2 N 3 ‐UN 2 of the system which were performed using a Sievert‐type apparatus showed that although these compounds are structurally dissimilar, they form a series of continuous solid solutions. Only UN 2 formed at high pressures and low temperatures. A pressure‐temperature schematic diagram and a temperature‐composition schematic diagram for a nitrogen pressure of 1 atm for the system uranium‐nitrogen are presented. At this pressure, UN decomposed at 2800° C and U 2 N 3 decomposed at 1345° C.