Effect of solutes on ideal shear resistance and electronic properties of magnesium: A first-principles study
Effect of solutes on ideal shear resistance and electronic properties of magnesium: A first-principles study
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DOI：
10.1016/j.actamat.2018.05.014
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发表时间：
2018-07-01
期刊：
影响因子：
9.4
通讯作者：
Solanki, K. N.
中科院分区：
文献类型：
--
作者：
Garg, P.;Adlakha, I;Solanki, K. N.
固溶强化或软化是提高机械性能的有效方法，特别是在镁基合金中，因为它们在室温下不能激活足够的非基底变形机制。因此，使用第一性原理计算，几种不同的合金元素的效果上的理想的剪切阻力跨各种滑移系统的镁进行了研究。结果表明，Ce或Zr溶质原子的加入降低了Mg的理想抗剪强度（软化），而Sn、Li或Zn溶质原子的取代提高了Mg的理想抗剪强度（强化）。发现添加Ce或Zr溶质原子后，Mg中的主导滑移系从基底部分（0001）[10（1）over-bar 0]变为棱柱形（10（1）over-bar 0）[11（2）over-bar 0];而添加Sn、Li或Zn溶质原子对塑性各向异性的影响可忽略不计。此外，电子态密度和价电荷转移，这提供了一个量子力学的洞察影响所观察到的软化/强化行为的潜在因素，进行了探讨。例如，电子态密度计算表明，Ce和Zr溶质原子d态的贡献降低了各自固溶体的电子结构稳定性，从而增强了滑移活动。最后，进行了理论分析，并引入了剪切性能参数，以了解所观察到的理想剪切阻力的变化对镁合金的宏观行为的影响。(C)2018 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Solution strengthening or softening is an effective way to enhance mechanical properties, especially in magnesium based alloys due to their inability to activate adequate non-basal deformation mechanisms at the room temperature. Hence, using first-principles calculations, the effects of several different alloying elements on the ideal shear resistance across various slip systems of Mg were investigated. The results reveal that the addition of a Ce or Zr solute atom decreases the ideal shear resistance (softening); whereas, the substitution of a Sn, Li or Zn atom increases the ideal shear resistance of Mg (strengthening). The dominant slip system in Mg was found to change from the basal partial (0001)[10(1)over-bar0] to prismatic (10(1)over-bar0)[11(2)over-bar0] with the addition of a Ce or Zr solute atom; whereas, the addition of a Sn, Li or Zn solute atom had negligible effect on the plastic anisotropy. Furthermore, the electronic density of states and valence charge transfer, which provides a quantum mechanical insight into the underlying factors influencing the observed softening/strengthening behavior, was probed. For instance, the electronic density of states calculations show that the contribution from d states of Ce and Zr solute atoms decreases the electronic structure stability of their respective solid solution, thereby enhancing slip activities. In the end, theoretical analyses were performed and a shearability parameter was introduced to understand the implications of the observed variation in ideal shear resistance on the macroscopic behavior of Mg alloys. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.