Abstract:A series of Zr-xFe (x=0.05, 0.2, 1.0, wt.%) alloys were designed to investigate the effect of Fe on the microstructure and corrosion behavior in 400 ℃/10.3 MPa superheated steam of zirconium alloys. The microstructures of alloy matrix and oxide layer were characterized using scanning electron microscope and transmission electron microscope. The results showed that the grain size of α-Zr matrix was obviously decreased by adding 0.05 wt.% Fe but remined nearly unchanged with a further increase in Fe content from 0.2 wt.% to 1.0 wt.%. Most of the Fe atoms in the zirconium alloys was found to precipitate as Zr3Fe secondary phase precipitates (SPPs). The SPP size was increased with the increase in Fe content, whereas its structure remained unchanged. Fe not only promoted the growth of columnar crystals in the oxide layer, but inhibited the columnar-to-equiaxed transformation, giving rise to a good corrosion performance of Zr-xFe alloys. Additionally, the corrosion resistance of Zr-xFe alloys was increased by increasing the Fe content. The stress accumulated at the oxide/metal (O/M) interface played a key role in the formation of sub-oxides in Zr-1.0Fe alloy during corrosion process, which can relieve the stress at the O/M interface, and thus largely improve the corrosion resistance by impeding the columnar-to-equiaxed transformation.