EDGE DISLOCATIONS IN FCC METALS - MICROSCOPIC CALCULATIONS OF CORE STRUCTURE AND POSITRON STATES IN AL AND CU
EDGE DISLOCATIONS IN FCC METALS - MICROSCOPIC CALCULATIONS OF CORE STRUCTURE AND POSITRON STATES IN AL AND CU
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DOI：
10.1103/physrevb.41.12441
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发表时间：
1990-06-15
影响因子：
3.7
通讯作者：
MANNINEN, M
中科院分区：
文献类型：
--
作者：
HAKKINEN, H;MAKINEN, S;MANNINEN, M
用分子动力学模拟方法研究了铝和铜中刃位错的结构（位错线方向[11 2]，Burgers矢量（a/2）[110]），该方法结合了有效介质理论，扩展到包括原子间的近邻相互作用。所观察到的平衡距离在两种金属中的肖克利部分位错同意从弹性理论的估计，通过使用已知的值的层错能和体积模量。连续介质理论导致的位错核心，这是窄于以前的结果的简单金属的对势计算。铜中的空位形成能在层错区的中心比在块体中高，这表明管道扩散只能发生在狭窄的部分位错核中。在第二部分的工作中，位错线和相关的点缺陷作为正电子陷阱的作用进行了研究，在这两种金属。纯位错线仅形成浅陷阱，但它可以是更深陷阱的前体状态，如位错线上的空位和单凹凸。这些缺陷的计算寿命与实验观察到的来自位错的寿命分量是很好的协议。
Structures of edge dislocations (dislocation line direction [11 2], Burgers vector (a/2)[110]) in aluminum and copper are studied with the molecular-dynamics simulation method which incorporates the effective-medium theory extended to include atomic interactions beyond the nearest neighbors. The observed equilibrium distance between the Shockley partial dislocations in both metals agrees well with the estimate evaluated from elasticity theory by using known values for the stacking-fault energy and the bulk modulus. Effective-medium theory leads to a dislocation core which is narrower than the previous results of the pair-potential calculations for simple metals. The vacancy formation energy in copper is higher at the center of the stacking-fault region than in the bulk, which suggests that pipe diffusion can take place only in the narrow partial dislocation core. In the second part of the work, the role of the dislocation line and of the associated point defects as positron traps are studied in both metals. The pure dislocation line forms only a shallow trap but it can be a precursor state for deeper traps, like vacancies and single jogs on the dislocation line. The calculated lifetimes for these defects are in good agreement with the experimentally observed lifetime components coming from dislocations.