The Fe-Zn phase diagram (Fig. 1) exhibits a gamma loop, extensive solubility of Zn in bcc Fe (alpha), and four intermediate phase: GAMMA, GAMMA_1, delta [1982 Kub]. The GAMMA phase forms peritectically at 782 deg C. The GAMMA_1 phase forms peritectoidally at 550 deg C. The delta and zeta phase form through peritectic reactions at 665 and 530 deg C, respectively. The final solidification at the Zn end yields zeta + (Zn). The GAMMA (Fe_3Zn_(10)) phase with a homogeneity range of 68.5-82.5 at. Percent Zn has the Cu_5Zn_8 type bcc strcture. GAMMA_1 (Fe_(11)Zn_(40)) has a range of 75-81 at. Percent Zn and is a related structure with a large fcc unit cell containing 8 formula units per cell. (GAMMA and GAMMA_1 are denoted as GAMMA_1 and GAMMA_2, respectively, in [1993 Bur] and other publication of Perrot and coworkers. In some recent publications, Tang denotes the GAMMA_1 phase as GAMMA'). The delta (FeZn_(10)) phase (denoted delta_1 by some authors) has a composition range of 86.5-91.8 at. percent Zn and hexagonal symmetry. The zeta (FeZn_(13)) phase (92.8-94 at. percent Zn) has the CoZn_(13) type monoclinic structure. Table 1 lists the crystal structure data on the intermediate phase of this system. Recently, [1994 Gra] determined the details of the site occupancy in the Fe-Zn compounds, using Mossbauer spectroscopy and x-ray diffraction.
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