Abstract:The effect of Cu content on the corrosion resistance of Zr-0.80Sn-0.4Nb-0.4Fe-0.10Cr-xCu alloys (x=0.05~0.5, mass fraction, %) was investigated in superheated steam at 400 oC and 10.3 MPa by autoclave tests. The microstructure of the alloys and the fracture surface of oxide films on the corroded specimens were observed by TEM and SEM, respectively. The results show that when the addition of Cu is below 0.2%, the second phase particles (SPPs) are mainly Zr(Fe,Cr,Nb)2 in smaller size, and few Zr3Fe with Cu. When the addition of Cu is above 0.2%, the SPPs of Zr2Cu are precipitated. The Zr2Cu particles become larger in size and more in amount with the increase of Cu content. The precipitates containing Cu are found in the alloy even with 0.05% Cu, which indicates that the Cu concentration in α-Zr matrix is very small. Cu addition of 0.05%~0.35% has little effect on the corrosion resistance of the alloys, but when the addition of Cu reaches 0.5%, the corrosion resistance of the alloy decreases, which is the worst one among the alloys.