The fundamental interactions between an edge dislocation and a random solid solution are studied by analyzing dislocation line roughness profiles obtained from molecular dynamics simulations of Fe0.70Ni0.11Cr0.19 over a range of stresses and temperatures. These roughness profiles reveal the hallmark features of a depinning transition. Namely, below a temperature-dependent critical stress, the dislocation line exhibits roughness in two different length scale regimes which are divided by a so-called correlation length. This correlation length increases with applied stress and at the critical stress (depinning transition or yield stress) formally goes to infinity. Above the critical stress, the line roughness profile converges to that of a random noise field. Motivated by these results, a physical model is developed based on the notion of coherent line bowing over all length scales below the correlation length. Above the correlation length, the solute field prohibits such coherent line bow outs. Using this model, we identify potential gaps in existing theories of solid solution strengthening and show that recent observations of length-dependent dislocation mobilities can be rationalized.

中文翻译：

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稠密固溶体中位错的长度尺度和无尺度动力学

通过分析从Fe0.70Ni0.11Cr0.19在一定应力和温度范围内的分子动力学模拟获得的位错线粗糙度轮廓，研究了边缘位错与无规固溶体之间的基本相互作用。这些粗糙度轮廓揭示了固定转变的标志性特征。即，在与温度相关的临界应力以下，位错线在两个不同的长度尺度范围内表现出粗糙度，该长度尺度范围被所谓的相关长度分开。该相关长度随施加的应力而增加，并且在临界应力（固定转变或屈服应力）处正式变为无穷大。在临界应力之上，线的粗糙度轮廓收敛到随机噪声场的轮廓。受这些结果的激励，基于相关长度以下所有长度范围内的相干线弯曲的概念，开发了一个物理模型。在相关长度以上，溶质场禁止这样的相干线弯曲。使用该模型，我们确定了现有的固溶强化理论中的潜在差距，并表明可以合理地确定长度依赖性位错迁移率的最新观察结果。