The previous review of this system by [1992Rag] presented an isothermal section at 597 deg C. Information on the phase relations and the activities of As in this ternary system is of interest in the recovery of As in nonferrous smelting processes or from ash produced in incinerators. Recently, [2004Voi] determined an isothermal section at 1150 deg C forAs-poor Fe-Co alloys.Binary SystemsThe Co-As system [Massalski2] contains several intermediate phases: Co_2As, Co_3As_2, CoAs, CoA_2, and CoAs_3. The Fe-As system [Masalski2] contains three compounds: Fe_2As, FeAs, and FeAs_2. None of these are stable at 1150 deg C. In the Co-Fe system [1984Nis], the face-centered cubic (fcc) Fe forms a continuous solid solution gamma with fcc Co over a wide range of temperature. The gamma ->alpha (bodycentered cubic, bcc) transformation temperature in Fe is initially raised by the addition of Co, reaching a maximum of 985 deg C at 45 at.percent Co. At 730 deg C, the bcc phase of equiatomic composition orders to a B2 structure via a second order transition.
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