A model for the dynamics of loop drag by a gliding dislocation
A model for the dynamics of loop drag by a gliding dislocation
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DOI：
10.1080/14786430500036371
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发表时间：
2005-05
影响因子：
1.6
通讯作者：
Z. Rong;Y. Osetsky;D. Bacon
中科院分区：
文献类型：
--
作者：
Z. Rong;Y. Osetsky;D. Bacon
自填隙原子簇是通过高能位移级联在金属中形成的，通常以具有完美伯格斯矢量的小位错环的形式。在孤立的情况下，它们能够在伯格斯矢量方向上进行快速、热激活的滑行，但不会响应均匀的应力场而移动。目前的工作考虑了它们在滑移位错应力的影响下滑行的能力。如果环可以被位错拖动，那么它将对位错与其滑移面附近的其他缺陷相互作用的有效横截面产生影响。位错弹性理论无法准确模拟晶格对环路阻力的抵抗力，因此这里通过原子级计算机模拟研究了铁和铜。结果表明，位于位错滑移面几纳米范围内的一排环可以以非常高的速度被拖动。与该过程相关的阻力系数已确定为金属、温度以及环路尺寸和间距的函数。提出了一种基于间隙环扩散率的环阻力模型。它根据所获得的数据进行测试，以了解阻力对移动位错的应力的影响以及位错脱离一排环的条件。
Clusters of self-interstitial atoms are formed in metals by high-energy displacement cascades, often in the form of small dislocation loops with a perfect Burgers vector. In isolation, they are able to undergo fast, thermally activated glide in the direction of their Burgers vector, but do not move in response to a uniform stress field. The present work considers their ability to glide under the influence of the stress of a gliding dislocation. If loops can be dragged by a dislocation, it would have consequences for the effective cross-section for dislocation interaction with other defects near its glide plane. The lattice resistance to loop drag cannot be simulated accurately by the elasticity theory of dislocations, so here it is investigated in iron and copper by atomic-scale computer simulation. It is shown that a row of loops lying within a few nanometres of the dislocation slip plane can be dragged at very high speed. The drag coefficient associated with this process has been determined as a function of metal, temperature and loop size and spacing. A model for loop drag, based on the diffusivity of interstitial loops, is presented. It is tested against data obtained for the effects of drag on the stress to move a dislocation and the conditions under which a dislocation breaks away from a row of loops.