Athermal migration of vacancies in iron and copper induced by electron irradiation
Athermal migration of vacancies in iron and copper induced by electron irradiation
复制标题
电子辐照诱导铁和铜中空位的非热迁移
DOI：
10.1080/14786435.2016.1275867
复制
发表时间：
2017
影响因子：
1.6
通讯作者：
S. Kano
中科院分区：
文献类型：
--
作者：
Y. Satoh;T.Sohtome;H. Abe;Y. Matsukawa;S. Kano
高能粒子辐照会引起点缺陷的非热迁移，这会影响热迁移可忽略不计的低温下的缺陷反应。我们对高压电子显微镜下电子辐照下反冲能驱动的铁和铜中的空位迁移进行了分子动力学模拟。 20 K 时，铁和铜中迁移所需的最小动能约为 0.8 和 1.0 eV，略高于空位迁移的活化能。在最小能量附近，只有当第一个最近邻（1NN）原子接收到朝向空位的动能时，迁移才会成功。即使偏转角较大，迁移也是由较高的动能引起的。在几个电子伏特和几十个电子伏特以上，空位分别直接迁移到 2NN 和 3NN 位点。通过多次碰撞和原子替换，空位迁移在较高动能下具有复杂的方向依赖性。空位迁移的概率随着动能的增加而增加，并且在 20-100 eV 范围内每次反冲事件保持在 0.3-0.5 次跳跃左右。在较高温度下，热能略微增加了动能低于 1.5 eV 的可能性。在 20 K 下 1.25 MV 电子照射下，铁和铜中的 1NN 原子的空位迁移截面分别为 3040 和 2940 个谷仓：之前的结果被高估了约五倍。
Irradiation with high-energy particles induces athermal migration of point defects, which affects defect reactions at low temperatures where thermal migration is negligible. We conducted molecular dynamics simulations of vacancy migration in iron and copper driven by recoil energies under electron irradiation in a high-voltage electron microscope. Minimum kinetic energy required for migration was about 0.8 and 1.0 eV in iron and copper at 20 K, which was slightly higher than the activation energy for vacancy migration. Around the minimum energy, the migration succeeded only when a first nearest neighbour (1NN) atom received the kinetic energy towards the vacancy. The migration was induced by higher kinetic energies even with larger deflection angles. Above several electron-volts and a few 10s of electron-volts, vacancies migrated directly to 2NN and 3NN sites, respectively. Vacancy migration had complicated directional dependence at higher kinetic energies through multiple collisions and replacement of atoms. The probability of vacancy migration increased with the kinetic energy and remained around 0.3–0.5 jumps per recoil event for 20–100 eV. At higher temperatures, thermal energies slightly increased the probability for kinetic energies less than 1.5 eV. The cross section of vacancy migration was 3040 and 2940 barns for 1NN atoms in iron and copper under irradiation with 1.25 MV electrons at 20 K: the previous result was overestimated by about five times.