Experimental determination of intermetallic phases, phase equilibria, and invariant reaction temperatures in the Fe-Zr system

The phase diagram of the binary Fe-Zr system was redetermined by differential thermal analysis (DTA), electron-probe microanalysis (EPMA), x-ray diffraction (XRD), and metallography in the whole range of compositions. The stable intermetallic phases of the binary system are the cubic and the hexagonal polymorphs of the Fe₂Zr Laves phase and the Zr-rich phases FeZr₂ and FeZr₃. While the cubic polymorph of the Laves phase is the stable structure at the stoichiometric Fe₂Zr composition, the hexagonal C36-type polymorph of the Laves phase is a high-temperature phase that is found at Zr concentrations as low as 26.6 at.%. The Zr-rich phases FeZr₂ and FeZr₃ have small homogeneity ranges of about 0.5 at.%. FeZr₂ is a high-temperature phase, stable between 780 and 951 °C. FeZr₃ decomposes peritectoidally at 851 °C. The frequently reported phase Fe₂₃Zr₆ (Fe₃Zr) is found not to be an equilibrium phase of the binary system.