障碍场中位错的热激活运动：障碍分布的影响
Thermally Activated Motion of Dislocations in Fields of Obstacles: Effect of Obstacle Distribution
摘要：
本文用计算机模拟的方法研究了位错在不同模型中穿过随机分布和相关分布的障碍物场时的热激活运动。的应变速率敏感性和强度进行评估的障碍物的强度，温度和施加的剪切应力。在阈值应力以上，位错运动经历从平滑到急动的过渡，即障碍物在高应力下以相关的方式被克服，而在低应力下它们被单独克服。这导致应变速率敏感性的显著降低。阈值应力取决于障碍物强度和温度。提出了一个模型来预测应变速率敏感性和平滑到突变的过渡应力。在低应力（蠕变条件）下，障碍物聚集对应变速率敏感性的影响很小，但在高应力下，它变得重要。它的结论是，模型的强度和应变率的敏感性，应包括更高的时刻，除了平均密度的障碍物密度分布。
英文摘要：
The thermally activated motion of dislocations across fields of obstacles distributed at random and in a correlated manner, in separate models, is studied by means of computer simulations. The strain rate sensitivity and strength are evaluated in terms of the obstacle strength, temperature and applied shear stress. Above a threshold stress, the dislocation motion undergoes a transition from smooth to jerky, i.e. obstacles are overcome in a correlated manner at high stresses, while at low stresses they are overcome individually. This leads to a significant reduction of the strain rate sensitivity. The threshold stress depends on the obstacle strength and temperature. A model is proposed to predict the strain rate sensitivity and the smooth-to-jerky transition stress. Obstacle clustering has little effect on strain rate sensitivity at low stress (creep conditions), but it becomes important at high stress. It is concluded that models for the strength and strain rate sensitivity should include higher moments of the obstacle density distribution in addition to the mean density.
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