Study on the formation of bulk Zr hydride and fracture behavior analysis

本文综述了块状氢化物的形成及断裂行为的研究进展。第一部分，研究了块状氢化物和无缺陷氢固溶体的制备方法，并测试了材料的物化性能和力学性能。它们分别具有独特的物理化学性质，而金属锆和氢化物的性质与钛、钇金属和氢化物的性质相似，这是因为这些氢化物的性质是由电负性决定的。第二部分研究了含氢和不含氢的锆Nb合金氧化膜的PEC性质，并讨论了充氢引起的杂质能级分布。所有样品的禁带宽度与氧化锆薄膜的禁带宽度一致。研究了纯Zr、不同Nb含量的Zr-Nb二元合金和添加Nb的Zircaloy-4合金中氢的最终固溶度。单相Zr-0.3Nb(Zr-0.3wt%Nb)样品的TSS与纯Zr的TSS基本相同。第三部分，利用ABAQUS版本6.5对裂纹尖端附近的氢扩散行为进行了有限元模拟。根据应力分布，氢迅速重新分布。在大多数情况下，裂纹尖端的氢气浓度在一秒钟内增加了10%以上。并对裂纹扩展速率进行了讨论。

This report summarizes the study on the formation of bulk Zr hydride and fracture behavior analysis.In the first part, the preparation methods for bulk Zr, Ti and Y hydride and hydrogen solid solution without defects were developed and the physicochemical and mechanical properties were measured. They have respectively unique physico-chemical properties, and that the properties for the zirconium metal and hydrides have similar properties to the titanium and yttrium metals and hydrides, since such properties for these hydrides are ruled by the electronegativity.In the second part PEC properties of oxide film of Zr-Nb alloy with or without hydrogen were studied, and the distribution of the impurity level induced by hydrogen charging was discussed. The band gap energy of all the samples was consistent with that of ZrO2 film. The terminal solid solubility of hydrogen (TSS) for pure Zr, Zr-Nb binary alloys with different Nb concentrations, and Nb added Zircaloy-4 was examined. The TSS of the a single-phase Zr-0.3Nb (Zr-0.3 wt% Nb) specimen appeared to be almost same as that of pure Zr.In the third part, the hydrogen diffusion behavior near the crack tip was simulated by FEM using ABAQUS ver.6.5. The hydrogen quickly redistributed according to the stress distribution. The hydrogen concentration at the crack tip increased more than 10 % within one second in most situations. The crack growth rate was discussed from the results.