The precipitation of hydrides in zirconium alloys is accompanied by a significant and anisotropic volumetric expansion. Previous literature quantified the misfit both theoretically and experimentally, but these values differ greatly; the experimental values are consistently lower. One possibility is that the experimental measurements include the effect of dislocations generated by the hydride, which relax the transformation stresses. To test this hypothesis, it is important to determine the stress field of a hydride and its associated dislocations, combined. A simple planar dislocation model was developed of the hydride—dislocation ensemble in $\alpha$-Zr. By capturing details of the dislocation structures given in the literature, it is shown in this study that including the interfacial dislocations largely reconciles the predicted and experimental values. Discrete dislocation plasticity is then used to model the diffuse plastic relaxation associated with hydride formation. The effects of plastic relaxation on the equilibrium hydrogen profile, hence the implications for subsequent hydride precipitation, are discussed. In particular, precipitation–dissolution cycles were simulated to calculate the magnitude of the residual hydrostatic tension, which is argued to be the primary cause of the “memory effect” for the re-precipitation of both $\gamma$ and $\delta$ hydrides.

锆合金中氢化物的析出伴随着显着的各向异性体积膨胀。以前的文献在理论上和实验上都对失配进行了量化，但这些值差异很大；实验值始终较低。一种可能性是实验测量包括由氢化物产生的位错的影响，它放松了转变应力。为了检验这一假设，重要的是确定氢化物的应力场及其相关位错的组合。一个简单的平面位错模型被开发了氢化物位错系综$\alpha$-锆。通过捕捉文献中给出的位错结构的细节，本研究表明，包括界面位错在很大程度上协调了预测值和实验值。然后使用离散位错塑性来模拟与氢化物形成相关的扩散塑性松弛。讨论了塑性松弛对平衡氢分布的影响，因此对随后的氢化物沉淀的影响进行了讨论。特别是，模拟沉淀-溶解循环以计算残余静水张力的大小，这被认为是两者再沉淀的“记忆效应”的主要原因$\gamma$和$\delta$氢化物。