The performance of Mg alloys is significantly influenced by the concentrations and solid solution behavior of the alloying elements. In this work, the solid solution behavior of 20 alloying elements in 190 ternary Mg alloy systems at 500 °C are systematically investigated. The solid solution behavior of a set of two different alloying elements in Mg alloy systems are suggested to be classified into three categories: inclusivity, exclusivity and proportionality. Inclusivity classification indicates that the two alloying elements are inclusive in α-Mg, increasing the joint solubility of both elements. Exclusivity classification suggests that the two alloying elements have a low joint solid solubility in α-Mg, since they prefer to form stable second phases. For the proportionality classification, the solubility curve of the ternary Mg alloy systems is a straight line connecting the solubility points of the two sub-binary systems. The proposed classification theory was validated by key experiments and the calculation of formation energies. The interaction effects between alloying elements and the preference of formation of second phases are the main factors determining the solid solution behavior classifications. Based on the observed solid solution features of multi-component Mg alloys, principles for alloy design of different types of high-performance Mg alloys were proposed in this work.

镁合金的性能受合金元素的浓度和固溶行为的显着影响。在这项工作中，系统研究了 20 种合金元素在 190 个三元镁合金体系中在 500 °C 下的固溶行为。建议将镁合金体系中两种不同合金元素的固溶行为分为三类：包容性、排他性和比例性。夹杂性分类表明两种合金元素都包含在α-Mg中，增加了两种元素的联合溶解度。排他性分类表明，这两种合金元素在 α-Mg 中具有较低的联合固溶度，因为它们更喜欢形成稳定的第二相。对于比例分类，三元镁合金体系的溶解度曲线是连接两个子二元体系的溶解度点的直线。所提出的分类理论通过关键实验和形成能量的计算得到验证。合金元素之间的相互作用效应和第二相形成的偏好是决定固溶行为分类的主要因素。基于观察到的多元镁合金的固溶体特征，本文提出了不同类型高性能镁合金的合金设计原则。