添加Cu和Mn对Zr-4合金耐腐蚀性能的影响

在Zr-4合金中添加Cu和Mn,用非自耗真空电弧炉熔炼了成分不同的7种锆合金,用高压釜在360℃/18.6MPa/0.01 mol/L Li OH水溶液中和400℃/10.3 MPa过热蒸汽中进行长期腐蚀试验,与出厂退火态Zr-4样品和经过重熔加工的Zr-4样品的耐腐蚀性能进行了比较。结果表明:添加0.05%~0.18%的Cu或0.07%~0.35%的Mn,或同时添加0.08%Cu和0.09%Mn都可以明显改善合金在Li OH水溶液中的耐腐蚀性能,在腐蚀增重曲线上没有出现明显的转折,耐腐蚀性能明显优于Zr-4合金;但是添加Cu或Mn后却使合金在400℃过热蒸汽中的耐腐蚀性能变坏,影响的程度随着Cu或Mn含量的增加而增加,并且Mn的有害作用比Cu更明显。讨论了氧化膜生长各向异性特征与添加合金元素之间的关系,解释了添加Cu和Mn合金元素后对Zr-4合金耐腐蚀性能在不同腐蚀条件下产生不同影响的原因。

Effect of Cu and Mn Alloying Elements on the Corrosion Behavior of Zircaloy-4

Seven zirconium alloys with copper and manganese additions in Zircaloy-4 were prepared by vacuum non-consumable arc melting method. The specimens were corroded by autoclave tests in lithiated water with 0.01 M LiOH at 360?C/18.6 MPa or in super-heated steam at 400 ?C/10.3 MPa. In comparison to the corrosion behavior of Zircaloy-4, the annealed Zircaloy-4 specimens obtained from commercial products and the remelted Zircaloy-4 specimens were also corroded together with the seven zirconium alloys specimens. The results show that the corrosion resistance was improved obviously by the addition of 0.05%~0.18% Cu or 0.07%~0.35% Mn, or 0.08%Cu and 0.09%Mn during the specimens corroded in lithiated water at 360?C. No transition occurred on the curve of the weight gain versus exposure time. Therefore the corrosion resistance of the seven alloy specimens was superior to that of Zircaloy-4. But the corrosion resistance of the specimens by the addition of Cu or Mn was worse than that of Zircaloy-4 during the specimens corroded in super-heated steam at 400?C. The tendency towards the degradation of corrosion resistance by the addition of Cu and Mn increased with the increase of the contents of Cu and Mn. The detrimental effect on the corrosion resistance by the addition of Mn is more obvious than that by the addition of Cu. The reason that the different effects on the corrosion resistance by the addition of Cu and Mn during the specimens corroded in different conditions was discussed and explained based on the relations between the anisotropic growth of oxide film and the addition of alloying elements.