Effect of one-dimensional migration of self-interstitial atom clusters on the decreasing behaviour of their number density in electron-irradiated alpha-iron
Effect of one-dimensional migration of self-interstitial atom clusters on the decreasing behaviour of their number density in electron-irradiated alpha-iron
复制标题
电子辐照α-铁中自填隙原子团一维迁移对其数密度降低行为的影响
DOI：
10.1080/14786435.2019.1673913
复制
发表时间：
2020
影响因子：
1.6
通讯作者：
S. Ohnuki
中科院分区：
文献类型：
--
作者：
Y. Abe and Y. Satoh;N. Hashimoto;S. Ohnuki
利用高压电子显微镜（HVEM）进行的原位观察表明，室温下电子辐照的α-铁中静止自填隙原子（SIA）团簇的数密度似乎在辐照早期达到峰值，并在长时间辐照时持续下降。原位 HVEM 实验使用薄箔样品；因此，SIA 团簇可能会因为逃逸到样本表面并通过一维 (1D) 迁移而相互合并而湮灭。在本研究中，我们推导了与实验揭示的一维迁移机制相关的分析模型，以检查团簇数密度的降低行为：(1) 样品表面内的杂质原子对一维迁移的 SIA 团簇的捕获，以及 (2) 由入射电子撞击引起的有界杂质原子对静止 SIA 团簇的去捕获。通过引入仅考虑捕获和解捕获过程的简单簇演化模型，模型计算表明，静止SIA簇的解捕获导致释放的SIA簇的表面湮灭，导致其数量密度下降。当将杂质浓度设置为与先前原位 HVEM 实验的估计值相同的顺序时，下降行为与实验数据更加一致。这一结果表明，SIA 簇的捕获和解捕获是行为减少的可能潜在过程。
An in- situ observation using high-voltage electron microscopy (HVEM) showed that the number density of stationary self-interstitial atom (SIA) clusters in electron-irradiatedα-iron at room temperature seems to reach its peak value at an early stage of irradiation and continuously decreases at the prolonged irradiation. A thin foil specimen is used in the in situ HVEM experiments; hence, the SIA clusters can annihilate because of their escape to the specimen surfaces and their mutual coalescence through one-dimensional (1D) migration. In this study, we derive analytical models associated with the experimentally revealed 1D migration mechanisms to examine the decreasing behaviour of the cluster number density: (1) trapping of one-dimensionally migrating SIA clusters by impurity atoms within the specimen surfaces and (2) detrapping of stationary SIA clusters from a bounded impurity atom caused by impact with incident electrons. By introducing a simple cluster evolution model that accounts for only the trapping and detrapping processes, the model calculation indicates that the detrapping of the stationary SIA clusters causes the surface annihilation of the liberated SIA clusters, leading to the decrease in their number density. The decreasing behaviour is in closer accordance with the experimental data when setting the impurity concentration in the same order as the estimation from the previous in situ HVEM experiment. This result suggests that the trapping and detrapping of the SIA clusters are the possible underlying processes for the decreasing behaviour.