Фазовая диаграмма системы Al-Na

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Al-Na (Aluminum-Sodium) J.L. Murray The Al-Na system exhibits a miscibility gap in the liquid phase and low solubility of Na in fcc (Al) and of Al in bcc (Na). The equilibrium of (Al) with the two liquid phases is of the monotectic type. Details of the phase equilibria have been examined only for Al-rich compositions. The assessed phase diagram does not differ significantly from the original [ Hansen] diagram. The temperatures of the liquidus and monotectic are corrected to agree with IPTS-68. The monotectic composition, 0.18 с 0.02 at.% Na, is based on an approximate thermodynamic treatment of the data. The assessed diagram was drawn from thermodynamic calculations, which provide the best consistency among the liquidus data [48Fin], monotectic temperature [ 48Fin], and miscibility gap [50Ran]. The liquid is treated as a regular solution with excess entropy and the fcc solid as a Henrian solution. The excess Gibbs energies are proposed as realistic only near the monotectic point and within the limitations of the approximations. The large excess entropy for the liquid suggests that [50Ran] may also have underestimated the Na content of the Al-rich liquid. Using electrical resistivity and metallographic techniques, [48Fin] found the maximum solubility of Na in solid (Al) to be less than 0.003 at.%, and [50Ran] further refined the maximum solubility to 0.0023 с 0.0005 at.%. The temperature dependence of the solidus could not be distinguished, however. [48Fin] found the solubility to increase with increasing temperature; [50Ran] argued, on the basis of a comparison of microstructures, that this was an artifact of too low quenching rates and that the equilibrium Na content is larger. 48Fin: W.L. Fink and L.A. Willey, Trans. AIME, 175, 364-371 (1948). 50Ran: C.E. Ransley and H. Neumfeld, J. Inst. Met., 78, 25-46 (1950). Published in Bull. Alloy Phase Diagrams, 4(4), Dec 1983. Complete evaluation contains 3 figures, 4 tables, and 7 references. Special Points of the Al-Na System