Фазовая диаграмма системы Fe-Ru

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Fe-Ru (Iron-Ruthenium) L.J. Swartzendruber and B. Sundman The equilibrium phases of the Fe-Ru system are (1) the liquid, L; (2) the bcc ( aFe) solid solution; (3) the bcc (dFe) solid solution; (4) the (gFe) solid solution; and (5) the cph (Ru) (or e) phase. The L + (Ru) =(gFe) peritectic at 1590 с20 C was reported by [59Obr], and the L + (gFe) = (dFe) peritectic at 1541 с 5 C was studied by [58Gib]. Because of the sluggishness and the diffusionless nature of the g <259> a and g <259> e transitions at low temperature, the (gFe)=(aFe) + (Ru) eutectoid temperature and the phase boundaries at low temperature are highly uncertain. Also, no data are available on the L/(Ru) phase boundaries. Using a thermodynamic model, the present authors obtained an optimized fit to the adjusted data of [58Gib], which yields a peritectic temperature of 1540.8 C with L, a, and g compositions of 5.6, 5.7, and 6.3 at.% Ru, respectively. The calculated diagram is provisionally accepted as the equilibrium diagram for this system, after adjustments to the thermodynamic parameterization. As with many Fe alloys with an expanded g field (e.g., Fe-Ni), the a = g transformations become sluggish and often have a martensitic nature. The experimental work necessary to determine the equilibrium phase boundaries in this region has not been performed. However, in analogy with the Fe-Ni work, where extensive experiments have been performed to determine the equilibrium boundaries, the a = g transformations can be used to place some restriction on the equilibrium boundaries. Data on the (gFe)/(Ru) equilibrium were provided by [59Obr], [60Rau], and [ 69Ste]. The tie line at 1327 C (0.21 to 0.36 at.% Ru) determined by [68Ste] using vapor pressure activity measurements was taken into account, as was their value of the Fe activity (0.75 in the (gFe) + (Ru) region at 1327 C). The triple-point pressure and the triple-point temperature of Fe are lowered by the addition of Ru. 37Fal: M. Fallot, Compt. Rend., 205, 227-230 (1937) in French. 38Mar: J. Martelly, Ann. Phys., 9, 318-333 (1938) in French. 58Gib: W.S. Gibson and W. Hume Rothery, J. Iron Steel Inst., 189, 243-250 ( 1958). 59Obr: W. Obrowski, Naturwissenschaften, 46, 624-625 (1959) in German. 60Rau: E. Raub and W. Plate, Z. Metallkd., 51(8), 477-481 (1960) in German. 65Bla: L.D. Blackburn, L. Kaufman, and M. Cohen, Acta Metall., 13, 533-541 ( 1965). 69Ste: G.L. Stepokoff and L. Kaufman, Acta Metall., 16, 13-22 (1968). Published in Bull. Alloy Phase Diagrams, 4(2), Sep 1983. Complete evaluation contains 3 figures, 4 tables, and 31 references. 1