Contribution to the Zr-rich part of the Zn-Zr phase diagram
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The reaction of zinc vapor with Zircaloy-4 and nuclear grade zirconium was investigated with various analytical techniques: optical metallography, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Based on the results, the Zr-rich part of the Zn-Zr phase diagram was revised. A eutectoid decomposition of (βZr) occurs at 718±6 °C with a composition of xZr=0.865; this temperature is lower than the previously accepted 750 °C eutectoid. The solubility of Zn in (αZr) was determined to be at x Zn=0.0236, a maximum at 725 °C. The intermetallic phase ZnZr2 was observed to occur in samples heat treated at 712 °C and 725 °C, but not in those heat treated at 700 °C and 775 °C.
KeywordsNuclear Grade Spend Fuel Eutectoid Reaction Nuclear Regulatory Commission Compositional Line
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