Фазовая диаграмма системы Mn-V

К оглавлению: Другие диаграммы (Others phase diargams)


Mn-V (Manganese-Vanadium) J.F. Smith and O.N. Carlson The assessed phase diagram for the V-Mn system is based on the work of [62Wat], with some modifications [57Hel, 75Suz]. The existence of a complete series of solid solutions between bcc V and dMn is well established [71Lug]. Also, the existence of a s phase is well known. The s phase has a tetragonal-type structure often found in transition metal systems. Considerable uncertainty exists with regard to the phase equilibria at Mn compositions above 85 at.% Mn, and work by [71Lug] has indicated the possible existence of two additional intermediate phases in this Mn-rich region. V and Mn have closely comparable atom factors for X-ray scattering. Through use of CrKa radiation, [62Wat] was able to distinguish between the two species in the bcc d and observed CsCl-type superlattice lines in a V52.2Mn47.8 alloy that had been quenched from 1150 C, crushed, and annealed for an extended length of time. [75Suz] determined the order-disorder temperature as a function of composition by means of specific heat measurements and differential thermal analyses. The dotted line in the present diagram is a plot of their results and shows the order-disorder boundary extending from approximately 33 to 55 at.% Mn, with a maximum at ~800 C and 45 at.% Mn. [62Wat] indicated the presence of a congruent transformation of the high- temperature (V,dMn) solid solution to the low-temperature tetragonal s phase near 75 at.% Mn and 1050 C. The width of the s phase field is not well defined, however. 57Hel: A. Hellawell and W. Hume-Rothery, Phil. Trans. Roy. Soc., A249, 417-459 (1957). 62Wat: R.M. Waterstrat, Trans. AIME, 224, 240-243 (1962). 71Lug: E. Lugscheider and P. Ettmayer, Monatsh. Chem., 102, 1234-1244 (1971). 75Suz: T. Suzuki and M. Hagiwara, Trans. Jpn. Inst. Met., 16, 473-479 (1975). Published in Phase Diagrams of Binary Vanadium Alloys, 1989. Complete evaluation contains 4 figures, 1 table, and 19 references. 1