Фазовая диаграмма системы Ag-Fe

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Ag-Fe (Silver-Iron) L.J. Swartzendruber The equilibrium phases of the Fe-Ag system are (1) the liquid; (2) a, the solid solution based on low-temperature bcc Fe; (3) d, the solid solution based on high-temperature bcc Fe; (4) g, the solid solution based on fcc Fe; and (5) (Ag), the solid solution based on fcc Ag. The mutual solubility of Ag and Fe is very low in both the solid and the liquid. The solubility of Ag in solid (Fe) reaches a maximum of approximately 0.022 at.% at 1398 C in the g phase. Data on the Fe-rich side for the solubility of Ag in the g phase were taken from [73Wri]. On the Ag-rich side, the data of [69Ber] were used for the solubility of Fe between 650 and 912 C. The remainder of the assessed diagram is estimated from thermodynamic modeling and is based on review of the work of [30Tam], [55Chi], and [58Gib]. The addition of Ag to electrolytic Fe leads to a retained Ag content as high as 0.69 wt.%, but with no improvement in the acid or atmospheric corrosion properties. In a study of the wetting behavior of molten Ag on Fe, high sensitivity to the presence of oxygen was observed, with wetting occurring only at low partial pressures of oxygen. Fe-Ag alloy films with up to 80 at.% Ag were made using co-evaporation onto cooled substrates. X-ray diffraction patterns for alloys containing 20 to 70 at.% Ag showed broad halos, indicating amorphous alloys. Resistivity measurements as a function of temperature showed the amorphous states to be stable up to ~250 C, with irreversible changes occurring above this temperature [83Tak]. Metastable thin-film alloys (5 to 10 mm thick) were prepared near the equiatomic composition by sputtering onto cooled substrates. X-ray diffraction and M”ssbauer measurements indicated that these films were amorphous alloys [83Chi]. The solubility of Ag in (Fe) is too small to determine any effect of Ag additions on the Curie temperature of pure Fe. Using the M”ssbauer effect to study the local magnetization for isolated Fe atoms in (Ag), a Kondo condensation temperature of approximately 1.3 K was obtained. The temperature at which the magnetic susceptibility reached a maximum for metastable alloy films containing 2 to 8 at.% Fe was found to be approximately proportional to the square root of the concentration, with a value of 20 K at 8 at.% Fe. The saturation induction of metastable Fe-Ag films demonstrated a monotonic decrease with increasing Ag content from 0 to 80 at.% Ag. The Curie temperature of metastable alloy films containing from 50 to 60 at.% Ag varied from 30 to -170 C. 30Tam: G. Tamman and W. Oelsen, Z. Anorg. Chem., 186, 277-279 (1930) in German. 55Chi: J. Chipman and T.P. Floridis, Acta Metall., 3, 456-459 (1955). 58Gib: W.S. Gibson and W. Hume-Rothery, J. Iron Steel Inst., 189, 243-250 ( 1958). 69Ber: J. Bernardini, A. Combe-Brun, and J. Cabane, C.R. Hebd. S‚ances Acad. Sci., 269, 287-289 (1969). 73Wri: H.A. Wriedt, W.B. Morrison, and W.E. Cole, Metall. Trans., 4, 1453-1456 (1973). 83Chi: C.L. Chien and K.M. Unruh, Phys. Rev. B, Condens. Matter, 28(3), 1214- 1218 (1983). 83Tak: M. Takao and H. Senno, J. Magn. Magn. Mater. 31-34, 949-950 (1983). Published in Bull. Alloy Phase Diagrams, 5(6), Dec 1984. Complete evaluation contains 5 figures, 5 tables, and 20 references. Special Points of the Fe-Ag System