Ab initio and atomistic study of generalized stacking fault energies in Mg and Mg-Y alloys
Ab initio and atomistic study of generalized stacking fault energies in Mg and Mg-Y alloys
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DOI：
10.1088/1367-2630/15/4/043020
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发表时间：
2013-04-15
影响因子：
3.3
通讯作者：
Neugebauer, J.
中科院分区：
文献类型：
--
作者：
Pei, Z.;Zhu, L-F;Neugebauer, J.
与纯Mg相比，镁-钇合金显示出显著改善的室温延展性。我们研究这个有趣的现象理论上在原子尺度上采用量子力学（所谓的从头算）和原子建模方法。具体来说，我们已经计算了广义层错能的五个滑移系统元素镁（Mg）和Mg-Y合金使用（i）密度泛函理论和（ii）一组嵌入原子方法（EAM）的潜力。这些计算预测，除了钇的结果在基滑移系的不稳定堆垛层错能的减少。特别是在一个I-2堆垛层错的情况下，预测的堆垛层错能量的减少，由于Y原子的实验测量验证。我们发现{11（2）over bar 2}< 11（2）over bar 3>非基底滑移系统的稳定层错能也有类似的降低。另一方面，其他能量沿着这个特定的伽马表面轮廓随着Y的添加而增加。在量子力学计算的同时，我们还开发了一种新的EAM Mg-Y势，并对其性能进行了全面测试。量子力学计算结果与原子理论计算结果的比较表明，新势函数适用于未来的大规模原子模拟。
Magnesium-yttrium alloys show significantly improved room temperature ductility when compared with pure Mg. We study this interesting phenomenon theoretically at the atomic scale employing quantum-mechanical (so-called ab initio) and atomistic modeling methods. Specifically, we have calculated generalized stacking fault energies for five slip systems in both elemental magnesium (Mg) and Mg-Y alloys using (i) density functional theory and (ii) a set of embedded-atom-method (EAM) potentials. These calculations predict that the addition of yttrium results in a reduction in the unstable stacking fault energy of basal slip systems. Specifically in the case of an I-2 stacking fault, the predicted reduction of the stacking fault energy due to Y atoms was verified by experimental measurements. We find a similar reduction for the stable stacking fault energy of the {11 (2) over bar2}< 11 (2) over bar3 > non-basal slip system. On the other hand, other energies along this particular gamma-surface profile increase with the addition of Y. In parallel to our quantum-mechanical calculations, we have also developed a new EAM Mg-Y potential and thoroughly tested its performance. The comparison of quantum-mechanical and atomistic results indicates that the new potential is suitable for future large-scale atomistic simulations.