Corrosion behavior of Zr−Nb alloys in 360°C water and 500°C supercritical water

Abstract

The corrosion behavior of Zr-0.4 wt.%Nb and Zr-1.5 wt.%Nb alloys was investigated in 360°C water and 500°C supercritical water. The two Zr-Nb alloys showed a similar corrosion rate in both corrosion conditions. However, in the 500°C supercritical water, the corrosion rate was increased by 23 times when compared to that of the 360°C water based on the weight gain at 240 days. In terms of the relationship between the corrosion and the precipitate characteristic, the E-Nb precipitates in the Zr-Nb alloys were considered to play an important role in the excellent corrosion resistance in the 360°C water, but its beneficial effect was not maintained in the 500°C supercritical water. The oxide characterization revealed that the tetragonal phase stability was more easily decreased from the interface to the surface in the oxide formed in the 500°C supercritical water.

Accelerated Formation of Oxide Layers on Zircaloy-4 Utilizing Air Oxidation and Comparison with Water-Corroded Oxide Layers

“…The HR-TEM and FFT pattern results (Figure 6) illustrate that the oxide scale present above the bubble region is mainly composed of Zr, Fe, and O-rich phases. The FFT pattern of region i indicates the presence of the hexagonal closed pack (hcp-ZrFe 2 ) phase, which is in agreement with the literature [23,24]. Meanwhile, in region ii, near a crack, the amorphous m-ZrO 2 was identified.…”