Polycrystalline iron under compression: Plasticity and phase transitions
Polycrystalline iron under compression: Plasticity and phase transitions
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DOI：
10.1103/physrevb.86.144111
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发表时间：
2012-10-16
影响因子：
3.7
通讯作者：
Urbassek, Herbert M.
中科院分区：
文献类型：
--
作者：
Gunkelmann, Nina;Bringa, Eduardo M.;Urbassek, Herbert M.
金刚石砧和冲击实验表明，铁在 13 GPa 左右的压力下会经历 bcc 到密排结构相变。原子模拟能够深入了解相变，但在单晶、有缺陷的单晶或多晶中，在相变之前不会发生任何可塑性。然而，多晶实验确实显示了可塑性的明确证据。在这里，我们使用几种原子间势研究多晶铁的均匀单轴压缩：三种嵌入原子模型势和一种改进的嵌入原子模型势。我们分析了晶界旋转和位错活动，发现位错活动量作为应变的函数在很大程度上取决于所使用的电势。这种变化可以用位错特性来解释，在这项工作中为每个势能进行了计算。
Iron undergoes a bcc to close-packed structural phase transition under pressure, at around 13 GPa, as shown by diamond anvil and shock experiments. Atomistic simulations have been able to provide insights into the transition, but without any plasticity occurring before the phase change, in single crystals, defective single crystals, or polycrystals. However, experiments in polycrystals do show clear evidence for plasticity. Here we study homogeneous uniaxial compression of polycrystalline Fe using several interatomic potentials: three embedded-atom-model potentials and one modified embedded-atom-model potential. We analyze grain-boundary rotation and dislocation activity, and find that the amount of dislocation activity as a function of strain depends greatly on the potential used. This variation can be explained in terms of the dislocation properties, calculated in this work for each of these potentials.