A spatially resolved analysis of dislocation loop and nanohardness evolution in proton irradiated Zircaloys
A spatially resolved analysis of dislocation loop and nanohardness evolution in proton irradiated Zircaloys
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质子辐照锆合金中位错环和纳米硬度演化的空间分辨分析
DOI：
10.1016/j.actamat.2024.119799
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发表时间：
2024
期刊：
影响因子：
9.4
通讯作者：
Koç Ö
中科院分区：
文献类型：
--
作者：
Koç Ö
质子辐照越来越多地被用作中子辐照的替代品，与中子辐照相比，质子辐照提供了类似的损伤结构，成本和时间都大大降低。然而，与中子不同的是，质子产生一个深度相关的损伤轮廓，它包含一个平台区和几十微米区域的布拉格峰，具体取决于材料和质子能量。在这里，我们证明了这种深度相关的损伤可以通过结合空间分辨微束同步X射线衍射位错分析和纳米压痕来获得对单个样品在不同剂量水平下的辐射损伤的新的理解。为此，为了从非常早期的阶段开始研究损伤演化，我们研究了在350°C下，0.01 dpa到17 dpa的Zircaloy-2和Zircaloy-4质子辐照样品的微结构演化和硬化行为。结果表明，基于SRIM的损伤深度预测与辐照诱导的位错外观和纳米硬度非常吻合。然而，即使在平台区内相对较低的损伤水平下，位错线密度和纳米硬度分布在整个辐照区域似乎是饱和的，即使dpa水平显著不同。当将位错环线密度与纳米硬度联系起来时，发现从某一点开始，随着线密度的增加，硬度仅有很小的增加。这种明显的差异可以通过从衍射线轮廓分析中确定的最高线密度的环尺寸减小以及将势垒强度与位错环尺寸相关联的分散势垒硬化模型的应用来解释。
Proton irradiation is increasingly used as a surrogate for neutron irradiation, providing similar damage structures at significantly lower costs and less time compared to neutron irradiation. However, in contrast to neutrons, protons produce a depth dependent damage profile that incorporates a plateau region and a Bragg peak in the tens of microns region depending on the material and proton energy. Here we demonstrate that this depth dependent damage can be utilised to obtain new understanding about irradiation induced damage at different dose levels from a single sample by combining spatially resolved micro-beam synchrotron X-ray diffraction-based dislocation analysis and nanoindentation. For this purpose, and to study the damage evolution starting from very early stages, we have investigated microstructure evolution and hardening behaviour of Zircaloy-2 and Zircaloy-4 proton irradiated samples between 0.01 dpa and 17 dpa at 350 °C. The results highlight good agreements of SRIM-based damage depth predictions with irradiation-induced dislocation appearance and nanohardness. However, at even relatively low damage levels within the plateau region, dislocation line density and nanohardness profiles appear saturated across the entire irradiated region, even when the dpa levels differed significantly. When relating dislocation loop line densities to nanohardness, it was found that from a certain point hardness increased only very slightly with increasing line densities. This apparent discrepancy can be explained by a decreasing loop size for the highest line densities identified by from the diffraction line profile analysis and the application of a Dispersed Barrier Hardening model that relates obstacle strength to dislocation loop size.