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Effect of solutes on ideal shear resistance and electronic properties of magnesium: A first-principles study
Acta Materialia ( IF 9.4 ) Pub Date : 2018-07-01 , DOI: 10.1016/j.actamat.2018.05.014
P. Garg , I. Adlakha , K.N. Solanki

Abstract 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 ¯ 0 ] to prismatic (10 1 ¯ 0)[11 2 ¯ 0] 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.

中文翻译:

溶质对镁理想剪切阻力和电子特性的影响:第一性原理研究

摘要 固溶强化或软化是提高机械性能的有效方法,尤其是在镁基合金中,因为它们无法在室温下激活足够的非基础变形机制。因此,使用第一性原理计算,研究了几种不同合金元素对不同镁滑移系统的理想剪切阻力的影响。结果表明,添加 Ce 或 Zr 溶质原子会降低理想的剪切阻力(软化);而 Sn、Li 或 Zn 原子的取代增加了 Mg 的理想剪切阻力(强化)。发现 Mg 中的主要滑移系统从基部 (0001) [ 10 1 ¯ 0 ] 变为棱柱形 (10 1 ¯ 0 )[11 2 ¯ 0] 并添加一个 Ce 或 Zr 溶质原子; 而添加 Sn,Li或Zn溶质原子对塑性各向异性的影响可以忽略不计。此外,还探讨了电子状态密度和价电荷转移,这提供了对影响观察到的软化/强化行为的潜在因素的量子力学洞察力。例如,电子态密度计算表明,Ce 和 Zr 溶质原子的 d 态贡献降低了它们各自固溶体的电子结构稳定性,从而增强了滑移活性。最后,进行了理论分析并引入了剪切性参数,以了解观察到的理想剪切阻力变化对镁合金宏观行为的影响。探索了状态的电子密度和价电荷转移,它提供了对影响观察到的软化/强化行为的潜在因素的量子力学洞察力。例如,电子态密度计算表明,Ce 和 Zr 溶质原子的 d 态贡献降低了它们各自固溶体的电子结构稳定性,从而增强了滑移活性。最后,进行了理论分析并引入了剪切性参数,以了解观察到的理想剪切阻力变化对镁合金宏观行为的影响。探索了状态的电子密度和价电荷转移,它提供了对影响观察到的软化/强化行为的潜在因素的量子力学洞察力。例如,电子态密度计算表明,Ce 和 Zr 溶质原子的 d 态贡献降低了它们各自固溶体的电子结构稳定性,从而增强了滑移活性。最后,进行了理论分析并引入了剪切性参数,以了解观察到的理想剪切阻力变化对镁合金宏观行为的影响。电子态密度计算表明,Ce 和 Zr 溶质原子的 d 态贡献降低了它们各自固溶体的电子结构稳定性,从而增强了滑移活性。最后,进行了理论分析并引入了剪切性参数,以了解观察到的理想剪切阻力变化对镁合金宏观行为的影响。电子态密度计算表明,Ce 和 Zr 溶质原子的 d 态贡献降低了它们各自固溶体的电子结构稳定性,从而增强了滑移活性。最后,进行了理论分析并引入了剪切性参数,以了解观察到的理想剪切阻力变化对镁合金宏观行为的影响。
更新日期:2018-07-01
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