Effect of Trace S Addition on the Corrosion Resistance of Zr-4 in Lithiated Water at 360 ℃

The effect of trace S addition (42~140 μg/g) on the corrosion resistance of Zr-4 alloy was investigated in lithiated water with 0.01 mol/L LiOH at 360 ℃/18.6 MPa by autoclave tests. The microstructures of the alloys and the oxide films formed on the alloys were observed and analyzed by TEM, EDS and SEM. The results show that the addition of trace S makes the corrosion resistance of Zr-4 better, and it becomes more obvious with the increase of S content. The solid content of S in α-Zr matrix was lower than 140 μg/g for the alloys in this study. The excess S was precipitated as Zr9S2 with tetragonal structure. Trace S addition in Zr-4 can improve the corrosion resistance in lithiated water with 0.01 mol/L LiOH at 360 ℃/18.6 MPa by delaying the formation of micro-pores and cracks, as well as the evolution process of ZrO2 columnar grains to equiaxed grains.