The previous review of this system [1992 Rag] presented a liquidus surface, two isothermal sections at 700 and 450 deg C, and a reaction scheme, mainly from the work of [1970 Kos], [1973 Ure], and [1990 Che]. In the last decade, a number of studies have examined the phase equilibria of this system, especially in Zn rich alloys at typical galvanizing temperatures. Binary Systems The Al-Fe phase diagram [1993 Kat] shows that the face-centered cubic (fcc) solid solution based on Fe is restricted by a gamma loop. The body-centered cubic (bcc) solid solution alpha exists in the disordered A 2 form, as well as the ordered B 2 and D0_3 forms. Apart from the high temperature phase epsilon, there are three other intermediate phases in the system: FeAl_2, Fe_2Al_5 (also denoted eta), and FeAl_3 (also called theta). The Al-Zn phase diagram updated by [1995 Oka] depicts a eutectic reaction at 381 deg C between (Al) and (Zn). In the (Al) region, a miscibility gap occurs in the solid state with the monotectoid reaction at 277 deg C and the critical temperature at 351.5 deg C. The Fe-Zn phase diagram (Fig. 1 under the Fe-Zn system on page 544) exhibits a gamma loop, extensive solubility of Zn in bee 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. The details of the site occupancy in the Fe-Zn compounds in alloys containing up to 1 wt. percent Al were studied by [1995 Cod], using Mossbauer spectroscopy and x-ray diffraction.
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