基于Pandat相图设计了一种新型的Mg-0.2Ce-0.2Ca (质量分数，%)三元合金，经常规挤压变形后的屈服强度约364 MPa、总合金化含量约0.4%，实现了高强度、低合金化。对挤压过程中不同阶段的组织进行表征，发现Mg-0.2Ce-0.2Ca合金中的孪晶存在于挤压的整个阶段，表现出了高的孪晶迁移阻力，并且在挤压变形的中后期，部分动态再结晶晶粒沿着孪晶变体交割区域形核，导致孪晶界面比例显著降低。Mg-0.2Ce-0.2Ca合金在挤压变形的早期阶段即存储了大量<c + a>位错，这些位错的运动阻力大，因此位错主导的回复再结晶机制直至挤压变形的后期才大量启动，并直接促进了该阶段镁合金中高比例超细晶粒的形成。分析认为，Mg-Ce-Ca合金挤压过程中微观组织演变的主要原因是Ca元素的添加提升了Mg基体孪晶运动阻力，且Ce、Ca元素的共添加诱导了多系滑移。

This study utilizes the Pandat software to design a novel ternary alloy, Mg-0.2Ce-0.2Ca (mass fraction, %). The Mg alloy samples are extruded conventionally and provide high strength and low alloying with yield strength of approximately 364 MPa and total content of only approximately 0.4%. The microstructures at different stages of extrusion are characterized, revealing the existence of twin in the Mg-0.2Ce-0.2Ca alloy throughout the extrusion process, indicating high twin migration resistance. In the middle and later stages of extrusion, dynamically recrystallized grains nucleate at regions of intersected twinning variants, leading to a significant reduction in the proportion of twinning interfaces. Moreover, during the early stage of extrusion, a large number of <c + a> dislocations are stored in the Mg-0.2Ce-0.2Ca alloy, and the dislocation-dominated recovery/recrystallization mechanism is functional until the late stage of extrusion due to the high slipping resistance of dislocations. This mechanism directly contributes to the formation of ultrafine grains in present Mg alloy. The results show that the addition of Ca increases the resistance of twinning motion in the Mg matrix, while the addition of Ce and Ca induces multisystem slip, which are the main mechanisms for regulating the microstructure evolution of Mg-Ce-Ca alloy during extrusion. These findings have significant implications for the development of new high-strength, low-alloyed Mg alloys.