The previous review of this system by [1986 Sin] presented three isothermal sections at 800, 650, and 500 deg C and a reaction scheme, mainly from the work of Koster [1956 Kos]. Recently, [1995 Tak] determined four isothermal sections in the temperature range of 880-700 deg C, with special reference to the effect of the magnetic transitions on the phase equilibria. Binary Systems The Co-Fe phase diagram [1984 Nis] is characterized by an extremely narrow solidification range. The fcc Fe forms a continuous solid solution gamma with alpha Co over a wide range of temperature. The gamma -> (alpha Fe) (bcc) transformation temperature 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 CsCl type B 2 structure. The Co-Zn phase diagram compiled by [Massalski 2] depicts a number of intermediate phases. The CoZn (beta) phase is listed as Cu type fcc structure by [Pearson 3] and W type bcc structure by [Massalski 2]. The CoZn (beta_1) phase has the beta Mn type cubic structure. Co_5Zn_(21) (denoted F by [1995 Tak] and gamma by [Massalski 2]) has the Al_4Cu_9 type c bic structure. The CoZn_9 phase (denoted gamma_1 by [Massalski 2]) has a gamma-brass related cubic structure [1986 Sin]. The CoZn_(13) phase (denoted gamma_2 by [Massalski 2]) is monoclinic and is isostructural with zeta (FeZn_(13)). For more details on the crystal structure data, see [Pearson 3] and [1986 Sin]. The Fe-Zn phase diagram (Fig. 1 under the Fe-Zn system page 544) exhibits a gamma loop, extensive solubility of Zn in bcc Fe (alpha), and four intermediate phases: GAMMA, GAMMA_1, delta and zeta. For crystal structure data of the Fe-Zn compounds, see Table 1 under Fe-Zn.
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