Фазовая диаграмма системы Fe-Os

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Fe-Os (Iron-Osmium) L.J. Swartzendruber and B. Sundman The equilibrium phases of the Fe-Os system are (1) the liquid, L; (2) the (aFe) solid solution; (3) the (dFe) solid solution; (4) the (gFe) solid solution; and (5) cph (Os). The L + (gFe) <259> (dFe) peritectic at 1552 C is based on the thermal analysis data of [63Buc]. Their original data were adjusted to agree with a melting point of 1538 C for pure Fe, and the data were then least-squares fitted to a regular-solution model. This procedure yielded a peritectic temperature 9 C higher than the original estimate of 1543 C by [63Buc]. Because of the scatter in the data and the uncertainty in the necessary adjustment, a relatively large uncertainty of с15 C is estimated for this peritectic temperature. No data are available on the (aFe)/(gFe) equilibrium boundaries below 912 C. The boundaries in the assessed diagram were constructed using the g <259> a and a <259> g transformation temperatures of [37Fal]. The measured transformation temperatures do not represent equilibrium phase boundaries. As with many Fe alloys with an expanded g field, the a = g transformations become sluggish and often have a martensitic nature. The equilibrium lines were drawn using the regular-solution model and assuming that the equal G values (T0 curves) should be approximately midway between the As and Ms transformations and equilibrium lines should straddle T0. No data are available on the (gFe)/(Os) equilibrium or the L + (Os)=(gFe) peritectic. The lines in the present diagram are calculated using the melting temperature of 3033 C for Os and the regular-solution model. Because the calculated diagram provides a good representation of the small amount of available data, it was taken as the provisional diagram. [37Fal] reported a decrease in Curie temperature of 11 C per atomic percent Os added and a decrease in average moment of approximately 0.02 Bohr magnetons per atomic percent Os. Up to about 5 at.% Os, the Asa<259>g temperature lies above the Curie temperature, permitting the metastable extension of the measured results into the a + g field. 37Fal: M. Fallot, Compt. Rend., 205, 227-230 (1937). 63Buc: R.A. Buckley and W. Hume-Rothery, J. Iron Steel Inst., 201, 121-124 ( 1963). Published in Bull. Alloy Phase Diagrams, 4(4), Dec 1983. Complete evaluation contains 3 figures, 2 tables, and 6 references. 1