摘 要
稀土元素因其独特的电子结构和化学性质，在镁合金中展现出显著的强化和细化晶粒效果，成为近年来材料科学领域的研究热点。本研究旨在探讨稀土元素对镁合金组织与性能的多重影响机制，特别是其在晶粒细化、相变调控及力学性能提升中的作用。通过采用熔炼铸造、热处理及微观组织表征等实验方法，结合X射线衍射、扫描电子显微镜及透射电子显微镜等先进分析技术，系统研究了不同稀土元素添加对镁合金显微组织、相组成及力学性能的影响。结果表明，稀土元素的加入显著细化了镁合金的晶粒尺寸，并促进了第二相的均匀分布，从而有效提升了合金的强度和延展性。特别是在Y-Mg合金体系中，稀土元素的添加不仅改善了合金的热稳定性，还显著提高了其高温力学性能。此外，研究发现稀土元素与镁基体的界面反应生成了高强度的金属间化合物，进一步增强了合金的综合性能。本研究的创新点在于揭示了稀土元素在镁合金中的多重作用机制，为高性能镁合金的设计与开发提供了理论依据和实验支持。
关键词：稀土元素；镁合金；晶粒细化；力学性能提升；金属间化合物
Abstract
Because of its unique electronic structure and chemical properties, rare earth elements show remarkable effect of strengthening and refining grain in magnesium alloys, which has become a research hotspot in the field of materials science in recent years. In this study, the effects of rare earth elements on the microstructure and properties of magnesium alloys were investigated, especially their roles in grain refinement, phase transformation regulation and mechanical properties improvement. The effects of different rare earth elements on the microstructure, phase composition and mechanical properties of magnesium alloy were studied by using the experimental methods of melting casting, heat treatment and microstructure characterization, combined with the advanced analytical techniques such as X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results show that the addition of rare earth elements significantly refines the grain size of the magnesium alloy and promotes the uniform distribution of the second phase, thus effectively improving the strength and ductility of the alloy. Especially in the Y-Mg alloy system, the addition of rare earth elements not only improves the thermal stability of the alloy, but also significantly improves the high temperature mechanical properties. In addition, it is found that the interfacial reaction between rare earth elements and magnesium matrix generates high strength interme tallic compounds, which further enhances the comprehensive properties of the alloy. The innovation of this study is to reveal the multiple action mechanisms of rare earth elements in magnesium alloys, which provides theoretical basis and experimental support for the design and development of high performance magnesium alloys.
Keywords： Rare Earth Elements; Magnesium Alloy; Grain Refinement; Mechanical Properties Improved; Interme tallic Compound
目 录
摘要 I
Abstract II
一、引言 1
二、稀土元素对镁合金微观组织的影响 2
（一）稀土元素对晶粒细化的作用 2
（二）稀土元素对第二相析出的调控 2
（三）稀土元素对晶界结构的影响 3
三、稀土元素对镁合金力学性能的影响 5
（一）稀土元素对镁合金强度的提升机制 5
（二）稀土元素对镁合金塑性的改善效果 5
（三）稀土元素对疲劳性能的影响分析 6
四、稀土元素对镁合金耐腐蚀性能的影响 7
（一）稀土元素对镁合金表面氧化膜的改性作用 7
（二）稀土元素对电化学腐蚀行为的影响 7
（三）稀土元素在不同环境下的腐蚀防护效果 8
结 论 9
参考文献 10
