人工晶体学报, 2023, 52 (3): 520, 网络出版: 2023-04-13  

微氧条件下镁氧化过程原位观测及机制研究

In Situ Observation and Mechanism Study on the Oxidation Process of Magnesium under Trace Oxygen Condition
作者单位
1 华北理工大学理学院, 唐山 063210
2 华北理工大学矿业工程学院, 唐山 063210
摘要
原位实时观测镁合金氧化反应及生长过程, 揭示其氧化过程与控制机理是目前镁表面处理领域的主流和热点。本文将纯镁薄膜样品在加热炉中400 ℃下保温10 h, 采用聚焦电子束技术在透射电子显微镜(TEM)中制备了带边的镁纳米孔, 并借助原位高分辨透射电子显微学技术, 对镁纳米孔边缘表面晶格在微氧条件下缓慢氧化及生长动态进行了原位观测及机制研究。结果表明: 通过原子吸附过程, Mg原子扩散到氧化物亚表层实现氧化, 通过MgO的外延式层层生长实现氧化物生长, 属于典型的各向异性生长, 表现出由{200}晶面包围的带边形貌特点。对晶格缺陷在氧化生长过程中作用的研究发现: 空位、位错带等缺陷促进氧化过程的进行; 孪晶的大角晶界可抑制晶界的旋转或者迁移, 有利于提高镁合金的耐腐蚀性。
Abstract
The study on the oxidation process of magnesium (Mg) alloy and corresponding control mechanism by in situ real-time observation has been a hotspot in the field of surface treatment for magnesium. In this study, magnesium film was kept for 10 h at 400 ℃ in a furnace, and the faceted Mg nanopores were prepared by focused electron beam technology under a transmission electron microscope (TEM). The slow oxidation and growth dynamics of the surface lattices at the vicinity of Mg nanopores under trace oxygen condition were observed using in situ high-resolution transmission electron microscopy techniques, while the corresponding mechanisms were also researched. The results show that the oxidation proceeds via an adatom process, resulting in the diffusion of Mg atoms from the substrate to the subsurface of oxides, and the oxidation growth process is mainly achieved via layer-by-layer epitaxial growth of MgO. The faceted morphology enclosed by {200} lattice planes attributes to the typical anisotropic growth. The study on the roles of defects in the process of oxidation growth shows that the defects, such as vacancies and dislocatios, promote the oxidation process, whereas the large-angle grain boundary of the twinning inhibits the rotation or migration of the grain boundary, which is conducive to improve the corrosion resistance of magnesium alloy.

卢竞涵, 吴淑静, 卢泽浩, 杜雨萌, 马永强, 曹冲. 微氧条件下镁氧化过程原位观测及机制研究[J]. 人工晶体学报, 2023, 52(3): 520. LU Jinghan, WU Shujing, LU Zehao, DU Yumeng, MA Yongqiang, CAO Chong. In Situ Observation and Mechanism Study on the Oxidation Process of Magnesium under Trace Oxygen Condition[J]. Journal of Synthetic Crystals, 2023, 52(3): 520.

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