Investigation of a new phase in Cu-containing Fe-Ni alloy for corrosion resistance behavior

ABSTRACTIn order to recognize the mechanisms of corrosion resistance in Cu-containing Fe-Ni alloys, two experimental composition 39.0Ni-57.1Fe-3.9Cu and 39.4Ni-57.7Fe-2.9Cu (at.-%) were designed according to the double-cluster model. The corrosion resistance measurements indicated that the alloy 39.0Ni-57.1Fe-3.9Cu possessed equal corrosion resistance to conventional steels 304 while the corrosion resistance of 39.4Ni-57.7Fe-2.9Cu was deteriorated by a new secondary precipitate phase. Observation by transmission electron microscopy and energy dispersive X-ray spectrometer showed evidence of the new phase in alloy 39.4Ni-57.7Fe-2.9Cu which having a crystal structure in a face-centered-cubic (FCC) symmetry and owning parameter a = 8.2A. A possible atomic composition was confirmed to be 16.8Ni-74.9Fe-8.3Cu.