Фазовая диаграмма системы Ac-Cr

К оглавлению: Другие диаграммы (Others phase diargams)


Ac-Cr (Actinium-Chromium) M. Venkatraman, J.P. Neumann, and D.E. Peterson Although no studies of the Cr-Ac system have been reported, it is assumed that Cr and Ac form a single eutectic phase diagram. Based on studies of other Cr- actinide systems, the following features are also assumed: (1) complete mutual solubility in the liquid state; (2) negligible mutual solubility in the solid state; and (3) the absence of intermediate phases. The assessed phase diagram for the Cr-Ac system has been calculated, despite the lack of thermodynamic data, by assuming that the liquid alloys form an ideal solution. According to the calculations, the eutectic point occurs at approximately 700 C and 70 at.% Ac. The Cr-actinide systems do not show the liquid miscibility gap that is typical of most of the Cr-lanthanide systems, probably because of the difference in the atomic volumes. The Cr-actinide systems are known for their ease of glass formation [78Gie, 78Pol], which is attributed to the low eutectic temperatures relative to the melting points of the pure components and the small terminal solid solubilities [83Gie]. 78Gie: B.C Giessen and R.O. Elliott, Proc. 3rd Int. Conf. Rapidly Quenched Metals, The Metals Society, London, 1, 406-411 (1978). 78Pol: D.E. Polk and B.C. Giessen, Metallic Glasses, J.J. Gilman and J.H. Leamy, Ed., American Society for Metals (1978). 83Gie: B.C. Giessen and S.H. Wang, Alloy Phase Diagrams, L.H. Bennett, T.B. Massalski and B.C. Giessen, Ed., North-Holland, New York, 289-294 (1983). Published in Bull. Alloy Phase Diagrams, 6(5), Oct 1985. Complete evaluation contains 1 figure, 1 table, and 3 references. 1


Диаграмма состояния Ac-Cr рассчитана, исходя из предположения об аналогичности ее строения другим диаграммам состояния актини­дов с Cr, построенным экспериментально [1]. Рассчитанная диаграм­ма представлена на рис. 1.


Она характеризуется эвтектическим превращением при 700 °С и практически отсутствием растворимости компонентов друг в друге в твердом состоянии. Концентрация Ac в эвтектической точке соответствует приблизительно 70 % (ат.).