Chromium from the stainless steel rollers used for driving the steel sheets into a galvanizing bath can enter the molten Zn and influence the reactions between the steel and the bath. Recently, [2000 Reu] determined a metastable isothermal section for this system at 460 deg C, applicable to industrial galvanizing conditions. Binary Systems The Fe-Cr phase diagram was reviewed by [1993 Itk]. Here, a gamma loop restricts the fcc phase gamma to about 11 wt. percent Cr. The bcc phase alpha is stable over a large region. The intermediate phase sigma, forms from alpha at 820 deg C around the mid-composition and decomposes eutectoidally at 545 deg C to Fe-rich and Cr-rich bcc phases. A partial phase diagram of the Cr-Zn system for Zn-rich alloys [1992 Mos] depicts two intermediate phases: CrZn_(17) (hexagonal) and CrZn_(13) (monoclinic) CrZn_(13) is isostructural with zeta (FeZn_(13)). A thermodynamic assessment of the Zn rich part of this system was reported very recently [2003 Reu]. The Fe-Zn phase diagram (Fig. 1 under the Fe-Zn system on 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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