Фазовая диаграмма системы Np-U

К оглавлению: Другие диаграммы (Others phase diargams)

Np-U (Neptunium-Uranium) R.I. Sheldon and D.E. Peterson The assessed phase diagram for the Np-U system is based on the work of [59Mar]. The phase diagram was determined using only 2 to 3 g of Np metal by successive dilution of the alloys with U. Considerable mutual solubility of the a and b modifications of these metals has been confirmed. The maximum solubility of U in (aNp) and (bNp) is 20 at.% U at 185 C and 26 at.% U at 612 C, respectively. Because of the steepness of the phase boundary, the solubility limits of (bNp) were inferred from high- temperature X-ray photographs rather than from thermal analysis. The (bNp) phase decomposes by a eutectoid reaction to (aNp) and d at 185 C, and by a peritectoid reaction to (gNp) and d at 612 C. The maximum solubility of Np in (aU) is 43 at.% Np at room temperature, and the maximum solubility of Np in (bU) is 26 at.% Np at 668 C. (bU) decomposes eutectoidally to (aU) and d at 645 с 5 C. At high temperatures, gNp and gU are completely miscible. Complete solubility is reasonable because gNp and gU are isostructural and have a favorable size factor. 59Mar: P.G. Mardon and J.H. Pearce, J. Less-Common Met., 1, 467-475 (1959). Published in Bull. Alloy Phase Diagrams, 6(3), Jun 1985. Complete evaluation contains 1 figure, 1 table, and 6 references. 1