陈敬昶,刘建国,陆绍敏,钟丽辉,陈丽萍,王远.Y掺杂MgZn2稳定性、电子结构和力学性能的第一性原理计算[J].表面技术,2023,52(8):444-450.
CHEN Jing-chang,LIU Jian-guo,LU Shao-min,ZHONG Li-hui,CHEN Li-ping,WANG Yuan.First-principles Calculations of Stability, Electronic Structure and Mechanical Properties of Y-doped MgZn2[J].Surface Technology,2023,52(8):444-450 |
| Y掺杂MgZn2稳定性、电子结构和力学性能的第一性原理计算 |
| First-principles Calculations of Stability, Electronic Structure and Mechanical Properties of Y-doped MgZn2 |
| 投稿时间：2022-07-20 修订日期：2023-02-16 |
| DOI：10.16490/j.cnki.issn.1001-3660.2023.08.040 |
| 中文关键词: MgZn2 Y掺杂 电子结构 力学性能 第一性原理计算 |
| 英文关键词:MgZn2 Y doping electronic structure mechanical properties first principles calculation |
| 基金项目:国家自然科学基金(51301144);云南省教育厅科学研究基金(2022Y574) |
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| Author | Institution |
| CHEN Jing-chang | Southwest Forestry University, Kunming 650224, China |
| LIU Jian-guo | YYCIN No.7 Construction Co., Ltd., Kunming 650100, China |
| LU Shao-min | Southwest Forestry University, Kunming 650224, China |
| ZHONG Li-hui | Southwest Forestry University, Kunming 650224, China |
| CHEN Li-ping | Southwest Forestry University, Kunming 650224, China |
| WANG Yuan | Southwest Forestry University, Kunming 650224, China |
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| 中文摘要: |
| 目的 稀土元素Y掺杂是改善7xxx系铝合金断裂韧性的重要途径，然而因其掺杂量极低，通过实验很难测定微量Y对7xxx系铝合金析出相及强韧机制产生的作用，限制了7xxx系铝合金的进一步发展。采用第一性原理计算方法探究Y掺杂对7xxx系铝合金中重要析出相MgZn2的影响机理，为7xxx系铝合金的微合金化强韧机理研究提供理论依据。方法 构建适于第一性原理计算、Mg/Zn的原子数分数比为1∶2的晶体模型，Y原子通过替换Mg或Zn原子的方式进行掺杂，通过能量计算、电子计算和弹性常数计算等分析Y掺杂对MgZn2能量稳定性、电子结构和力学性能的影响机理。结果 经Y掺杂后，形成3种固溶体Mg3Zn8Y、Mg4Zn7Y-1和Mg4Zn7Y-2，它们的形成热均小于0，即它们均可自发形成且稳定存在。通过结合能计算发现，3种固溶体的结合能都小于MgZn2的结合能，说明Y掺杂促进了MgZn2的稳定性。通过电子结构分析发现，Y掺杂后与Mg、Zn原子形成强的共价键，增强了体系的稳定性，Mg-Zn原子间形成了强离子键，MgZn2中Zn-Zn原子间的共价键变为强离子键。力学性能计算结果表明，经Y掺杂后MgZn2的硬度降低、韧性上升， 即Y掺杂增强了7xxx系铝合金中重要弥散析出相MgZn2的韧性，从而提升了7xxx系铝合金的断裂韧性和抗疲劳能力。结论 基于计算结果分析得出，Y掺杂提升了MgZn2的稳定性、键合强度和断裂韧性，相关计算分析为微量Y掺杂增强7xxx系铝合金断裂韧性的实验分析提供了指导。 |
| 英文摘要: |
| Micro-alloying of rare earth element Y is an important way to strengthen the fracture toughness of 7xxx series aluminum alloys, but it is hard to determine the effect of Y doping on the precipitated phase and toughness mechanism of 7xxx series aluminum alloys in experiments because the doping amount of Y is very small, which limits the further development of 7xxx series aluminum alloys. Therefore, the influence mechanism of Y doping on the important precipitation phase MgZn2 in 7xxx series aluminum alloys was analyzed by the first principles calculation method in this paper, in order to provide a theoretical basis for study of the strengthening and toughening mechanism of 7xxx series aluminum alloys by micro-alloying elements. A crystal model with the atomic ratio of Mg/Zn=1∶2, which was suitable for first-principles calculation, was built in this paper, then Mg or Zn atoms were replaced with Y atoms by orderly substitution doping and the influence mechanism of Y doping on the energy stability, electronic structure and mechanical properties of MgZn2 was analyzed by energy calculations, electronic calculations and elastic constant calculations. The results showed that after Y doping, the formation heat of Mg3Zn8Y, Mg4Zn7Y-1 and Mg4Zn7Y-2 was −19.998, −7.14 and −3.916 kJ/mol respectively, so the three solid solutions could spontaneously form and exist stably. It could be found that the structural stability of MgZn2 could be enhanced by Y doping, and the formed solid solution Mg3Zn8Y with Y substituting for Mg had the most stable structure and the formed solid solution Mg4Zn7Y-2 with Y substituting for had the worst stability, since the binding energy of MgZn2, Mg3Zn8Y, Mg4Zn7Y-1 and Mg4Zn7Y-2 were −132.664, −163.584, −153.648 and −150.424 kJ/mol, respectively, obtained from the computation of binding energy. The solid solution Mg4Zn7Y-2 hardly formed with Y doping due to their poor formation ability and structural stability, so the electronic structure and mechanical property analysis didn’t be considered in this paper. Secondly, it was discovered that Mg-Zn atom formed an ionic bond and the main covalent bond in MgZn2 came from Zn-Zn atom without Y doping from the analysis of electronic structure. When Y atoms were doped, the main covalent bond in the system came from the bonding between Y, Zn or Mg atoms, the covalent bond of Zn-Zn atoms was converted into a stronger ionic bond, and the ionic bond between Mg-Zn atoms was likewise considerably strengthened. The doped Y atoms formed a strong covalent bond with other atoms, which promoted the stability of the system. It could be concluded that the metallic character of the system increased and the Mg4Zn7Y possessed the strongest metallic character from the analysis of the gross density of states. Finally, the mechanical property calculation showed that the hardness of MgZn2 decreased and the toughness increased after Y doping, i.e., Y doping enhanced the toughness of the important dispersed precipitation phase MgZn2 in 7xxx series aluminum alloys, and consequently increased the fracture toughness and anti-fatigue ability of 7xxx series aluminum alloys. Based on the above calculation and analysis, the doped Y can improve the stability, bond strength and fracture toughness of MgZn2 phase. In addition, relevant calculation and analysis can provide a guidance for experimental analysis on enhancing the fracture toughness of 7xxx series aluminum alloys by a little Y doping. |
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