累积退火参数与含Nb锆合金耐腐蚀性能关系述评

累积退火参数(A)被广泛用于评价核反应堆用Zr-Sn系合金的耐水侧腐蚀性能。对于累积退火参数在新发展的含Nb锆合金中的应用,迄今未有一致意见,有学者认为传统的累积退火参数不再适用于含Nb锆合金的耐腐蚀性能的评价。本文综述了累积退火参数在常见牌号核用锆合金中的研究概况,并从A值的本质出发,解释了累积退火参数与锆合金微观组织之间的联系及其评价耐腐蚀性能的微观原因。提出合金元素的扩散速率(Fe、Cr扩散很快,Nb扩散极慢)是累积退火参数是否起作用的决定因素。指出累积退火参数可以直接用来评价低Nb锆合金的耐腐蚀性能,即A值越小,第二相粒子越细小弥散,合金的耐腐蚀性能越佳。

Review on Correlation of Accumulated Annealing Parameter and Corrosion Resistance of Nb-containing Zirconium Alloys

Accumulated annealing parameter has been widely used for indicating the corrosion resistance of Zircaloys.However,for Nb-containing zirconium alloys,a unanimous conclusion has not been drawn yet.Even more,some researchers confirm that the accumulated annealing parameter is totally inadequate in this type of alloy.Based on its physical nature,we summarize the correlation of the accumulated annealing parameter and alloy microstructure.Further,the reason why it can identify the corrosion resistance in some specific alloys is explained tentatively.It is suggested that the diffusion rate of alloying elements(Fe and Cr diffusing fast while Nb diffusing extraordinarily slow) determines whether the accumulated annealing parameter will work.A clear conclusion is drawn that the accumulated annealing parameter can identify the low-Nb zirconium alloy’s corrosion resistance,i.e.,the smaller the value of the accumulated annealing parameter,the finer the second phase particles and then the better the corrosion resistance of alloy.