(1. 西安理工大学 材料科学与工程学院, 西安710048;
2. 陕西理工学院 机械工程学院, 汉中723003)
摘 要: 研究往复挤压变形对Mg-4Al-2Si合金组织和性能的影响性能，探讨基体组织和Mg2Si颗粒相的细化效果与细化机制，分析Mg2Si颗粒对再结晶的影响规律。结果表明：挤压过程中发生受位错攀移控制的动态再结晶，通过晶界迁移、亚晶合并与转动机制形成细小的α(Mg)再结晶等轴晶；随着往复挤压道次的增加，动态再结晶速度加快，晶粒尺寸迅速减小；α(Mg)与Mg2Si的晶粒尺寸在铸态下分别为45和60 µm，往复挤压6道次后，晶粒尺寸减小到3和1 µm，形成了细小、均匀的α(Mg)等轴晶组织，Mg2Si颗粒呈细小、弥散分布；合金的力学性能随往复挤压道次的增加而显著提高。
关键字: Mg-4Al-2Si镁合金；往复挤压；动态再结晶；力学性能
Mg-4Al-2Si Mg alloy by
reciprocating extrusion
（1. School of Materials Science and Engineering, Xi’an University of Technology, Xi’an 710048, China;
2. School of Mechanical Engineering, Shanxi University of Technology,Hanzhong 723003, China）
Abstract:The effects of reciprocating extrusion deformation on microstructures and properties of Mg-4Al-2Si alloys were studied, and the mechanisms of grain refinement of α(Mg) and Mg2Si particles, as well as the effect of Mg2Si particles on the recrystallization were investigated. The results show that dynamic recrystallization controlled by dislocation climbing takes place during the reciprocating extrusion process. The equiaxed grains are formed by crystal boundary migration, subgrain merge and twist rotation by recrystallization. The grain size decreases and the rate of dynamic recrystallization increases with increasing passes of reciprocating extrusion. The grain sizes of as-cast α(Mg) and Mg2Si particles decrease from 45 and 60 µm to 3 and 1 µm after 6 passes of reciprocating extrusion, respectively. Tthe microstructures are characterized by the fine equiaxed α(Mg) grain with homogeneous distribution of fine Mg2Si particles. The mechanical properties of alloys are improved obviously with increasing reciprocating extrusion passes.
Key words: Mg-4Al-2Si Mg alloy; reciprocating extrusion; dynamic recrystallization; mechanical properties
