SIMULATIONS OF THE ATOMIC STRUCTURE, ENERGETICS, AND CROSS SLIP OF SCREW DISLOCATIONS IN COPPER
SIMULATIONS OF THE ATOMIC STRUCTURE, ENERGETICS, AND CROSS SLIP OF SCREW DISLOCATIONS IN COPPER
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DOI：
10.1103/physrevb.56.2977
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发表时间：
1997-08
影响因子：
3.7
通讯作者：
Torben Rasmussen;Karsten Wedel;T. Leffers;Ole Bøcker
中科院分区：
文献类型：
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作者：
Torben Rasmussen;Karsten Wedel;T. Leffers;Ole Bøcker
使用纳米级原子模拟，可以通过不受弹性理论限制的方法来解决面心立方金属 (cid:126) Cu (cid:33) 中解离螺旋位错的交叉滑移问题。重点是通过 Friedel-Escaig (cid:126) FE (cid:33) 交叉滑移机制与交叉滑移相关的不同位错配置。确定了该机构的无应力横向滑移激活能和激活长度。我们证明了有限元横向滑移机制中横向滑移所必需的两个收缩是不等价的，并且仅具有这些收缩之一的位错配置比两个平行的肖克利部分在能量上更有利。研究了位错垂直于自由表面的影响。结果与透射电子显微镜实验和线弹性理论的预测定性一致，显示自由表面附近部分的重组或排斥。自由表面的这种复合在交叉滑移的情况下可能很重要，因为它允许单独产生上述能量上有利的收缩。此外，我们观察到偏向于位于与表面台阶平行的滑行平面中的强烈偏好。我们对两个符号相反的螺旋位错进行了模拟，其中一项模拟显示表面成核交叉滑移导致两个位错随后湮灭。可以监视歼灭情况
Using nanoscale atomistic simulations it has been possible to address the problem of cross slip of a dissociated screw dislocation in an fcc metal (cid:126) Cu (cid:33) by a method not suffering from the limitations imposed by elasticity theory. The focus has been on different dislocation configurations relevant for cross slip via the Friedel-Escaig (cid:126) FE (cid:33) cross-slip mechanism. The stress free cross-slip activation energy and activation length for this mechanism are determined. We show that the two constrictions necessary for cross slip in the FE cross-slip mechanism are not equivalent and that a dislocation configuration with just one of these constrictions is energetically favored over two parallel Shockley partials. The effect of having the dislocation perpendicular to a free surface is investigated. The results are in qualitative agreement with transmission electron microscopy experiments and predictions from linear elasticity theory showing recombination or repulsion of the partials near the free surface. Such recombination at the free surface might be important in the context of cross slip because it allows the creation of the above-mentioned energetically favorable constriction alone. In addition we observe a strong preference for the partials to be in a glide plane parallel to the surface step. We have performed simulations of two screw dislocations of opposite signs, one simulation showing surface nucleated cross slip leading to subsequent annihilation of the two dislocations. It was possible to monitor the annihilation