利用高压釜腐蚀实验研究了Zr-1Nb-xBi(x=0.05-0.3, 质量分数, %)合金在360 ℃和18.6 MPa去离子水中的耐腐蚀性能. 结果表明, 在Zr--1Nb合金的基础上添加Bi能明显改善其耐腐蚀性能, 且随着Bi含量的增加, 合金的耐腐蚀性能进一步提高.合金显微组织的TEM观察和EDS分析表明, 合金中存在ZrNbFe型和β-Nb第二相,Bi含量对第二相的种类、尺寸和数量没有明显的影响; 0.3%的Bi可全部固溶在α-Zr基体中, 且不影响Nb的固溶含量. 氧化膜断口和内表面形貌的SEM观察表明,固溶在α-Zr基体中的Bi能够明显延缓氧化膜显微组织的演化, 包括孔隙发展成为微裂纹的过程和柱状晶向等轴晶的转变.

The effect of Bi contents on the corrosion resistance of Zr-1Nb-xBi (x=0.05-0.3, mass fraction, %) was investigated in deionized water at 360 ℃ and 18.6 MPa by autoclave tests. The results show that the corrosion resistance of Zr-1Nb alloy can be improved by adding Bi,and the more the Bi content is, the better the corrosion resistance is.TEM and EDS analyses on the microstructures of the alloys show that there are two types of second phase particles (SPPs), including ZrNbFe and β-Nb. The Bi contents have little effect on the type, size and amount of SPPs, 0.3%Bi can be completely dissolved in α-Zr matrix and has no influence on the solution content of Nb inα-Zr matrix. From the fracture and inner surface morphology of oxide films observed by SEM, it can be seen that the Bi dissolved in theα-Zr could noticeably slow down the microstructural evolution of oxide film, including the propagation of micro--cracks and the transformation from columnar grains to equiaxed grains in the oxide film.