新锆合金氧化膜微观组织结构的研究

Study on Microstructure of Oxide Film for New Zirconium Alloys

摘要:

研究了氧化膜的微观组织结构，研究结果表明，对采用不同热处理的两种新锆合金，无论从内到外，氧化膜结构均极为相似；不同热处理对氧化膜结构影响在于是否有第二相易于嵌入ZrO2中，累计退火参数值越高，嵌入可能性大；该嵌入的沉淀相促进氧化膜化膜从其它结构到单斜结构的转变，残留于原金属晶界处的第二相促使晶界开裂。靠近氧化膜金属基体氧化膜内表面观察表明，氧化膜生长是不均匀的，呈菜花状；腐蚀速率越高，菜花尺寸越大，凸起越严重。本研究说明，采用低温加工工艺获得尺寸较小的沉淀相是合金耐蚀性能改善的基本途径。

Abstract:

The microstructure of oxide film for new zirconium alloys was studied.The results show that the microstructure of oxide films is much alike from inner surface to outer surface for NZ2 and NZ8 alloys by different intermidiate annealling treatment.The effect of different annealling lies in that whether there are precipitates embedding in oxide,the higher the accumulative annealing parameters,the more the probability of precipitates embedding.The embedded precipitates promote oxide transition to monoclinal structure and promote cracking along the former alloys grain boundary.SEM shows that the oxide film grows in a inhomogeneous way.The film in the inner surface appears in morphology like Cauliflouer,which is realted to accelerating corrosion.The faster the corrosion,the bigger the "Cauliflower"in size is.The results obtained by this study comfirm that adopting low temperature working process can make further refining of precipitates size,and this is the effective way to improve corrosion resistance of new zirconium alloys.