Knowledge on phase stability in Fe-rich Fe-Cr-Ni-Zr alloys is needed for the development of Laves phase strengthened Fe-Cr-Ni-Zr ferritic alloys. These alloys show promising applications as new cladding materials of nuclear reactors due to enhanced high-temperature strength and resistance to creep and irradiation hardening. Phase stability in four Fe-rich Fe-Cr-Ni-Zr alloys was carefully investigated using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques. The samples were arc-melted and heat treated at 973.15 K (700 °C) for 1275 hours and 1273.15 K (1000 °C) for 336 hours. The experimental results showed extensive solubility of Ni in the intermetallic phases Fe23Zr6 and Fe2Zr_C15. Nickel stabilizes the Laves Fe2Zr_C15 structure more than the C36 and C14 structures. In addition to Fe23Zr6 and Fe2Zr_C15, Ni7Zr2 was found to be stable in samples with higher Ni content and lower annealing temperature. The Fe2Zr_C15 and Fe23Zr6 coexist with the body-centered cubic matrix phase in all samples regardless of compositions and temperatures.
