Elastic trapping of dislocation loops in cascades in ion-irradiated tungsten foils
Elastic trapping of dislocation loops in cascades in ion-irradiated tungsten foils
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DOI：
10.1088/0953-8984/26/37/375701
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发表时间：
2014-02
期刊：
影响因子：
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通讯作者：
D. Mason;X. Yi;X. Yi;M. Kirk;S. Dudarev
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文献类型：
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作者：
D. Mason;X. Yi;X. Yi;M. Kirk;S. Dudarev
利用原位透射电子显微镜（TEM）观察到，在极低的自离子辐照下，超高纯度钨箔形成纳米级位错环。TEM图像分析显示，最大的环以棱柱形1/2 < 111 >型为主，具有空位特征。这种位错环的形成是令人惊讶的，因为孤立的环被认为是高度可移动的，并且应该从箔中逃脱。在这项工作中，我们表明，观察到的环的大小和数量密度可以用环不是孤立的事实来解释——在级联中形成的环彼此相互作用，并与空位团簇相互作用，也在级联中形成，通过远程弹性场，防止环从箔上逃逸。我们发现，只有考虑到回路之间的弹性相互作用，实验结果才能很好地再现级联演化的物体动力学蒙特卡罗模拟。我们的分析强调了缺陷之间的弹性相互作用对辐照材料微观结构演变的深刻影响。
Using in situ transmission electron microscopy (TEM), we have observed nanometre scale dislocation loops formed when an ultra-high-purity tungsten foil is irradiated with a very low fluence of self-ions. Analysis of the TEM images has revealed the largest loops to be predominantly of prismatic 1/2〈111〉 type and of vacancy character. The formation of such dislocation loops is surprising since isolated loops are expected to be highly mobile, and should escape from the foil. In this work we show that the observed size and number density of loops can be explained by the fact that the loops are not isolated—the loops formed in close proximity in the cascades interact with each other and with vacancy clusters, also formed in cascades, through long-range elastic fields, which prevent the escape of loops from the foil. We find that experimental observations are well reproduced by object Kinetic Monte Carlo simulations of evolution of cascades only if elastic interaction between the loops is taken into account. Our analysis highlights the profound effect of elastic interaction between defects on the microstructural evolution of irradiated materials.