纳米组织Zr-4合金氧化膜中应力应变研究

研究纳米组织与普通粗晶组织Zr-4合金在400℃水腐蚀过程中氧化膜内应力的演变特征。结果表明,纳米基底上形成的单斜相ZrO2(m-ZrO2)和四方相ZrO2(t-ZrO2)的微观应变值,比普通基层上形成的m-ZrO2和t-ZrO2相的微观应变值大,160d时普通基底上t-ZrO2相的σ值约为1200MPa,而在纳米基底上的t-ZrO2相的σ值则为1900MPa,说明表面纳米化处理后Zr-4合金氧化膜内,氧化膜/金属界面(O/M界面)处所受的压应力比普通组织的O/M界面所受的压应力大。纳米化后均匀细小的晶粒尺度以及高的压应力,有利于在O/M界面处形成一层具有保护作用的致密的腐蚀产物膜(t-ZrO2层),从而改善Zr-4合金的抗腐蚀性能。

Research on stress-strain of oxide films of nanocrystalline Zircaloy-4

The stress evolution characteristic in the oxide films of the nanostructure and normal structure Zr-4 alloy in the water at 400 ℃ was studied in this paper. The results indicate that the micro strain of m-ZrO2 and t-ZrO2 formed in the nanostructure is larger than that formed in the normal structure. The σ value of t-ZrO2 formed in the normal bases is about 1 200 MPa, and the σ value of the t-ZrO2 formed in the nanocrystalline bases is about 1 900 MPa after 160 days. It explains that the compressive stress of the oxide film/metal interface in the nanocrystalline is larger than that in the coarse grain. After nanocrystallized treatment,the homogeneous grain size and high compressive stress are beneficial to forming a compact oxide film (t-ZrO2) which has the protection effect,and that can improve the resistant corrosion of the zircaloy-4 alloy.