(1. 西安理工大學(xué) 材料科學(xué)與工程學(xué)院, 西安710048;
2. 陜西理工學(xué)院 機(jī)械工程學(xué)院, 漢中723003)
摘 要: 研究往復(fù)擠壓變形對(duì)Mg-4Al-2Si合金組織和性能的影響性能，探討基體組織和Mg2Si顆粒相的細(xì)化效果與細(xì)化機(jī)制，分析Mg2Si顆粒對(duì)再結(jié)晶的影響規(guī)律。結(jié)果表明：擠壓過(guò)程中發(fā)生受位錯(cuò)攀移控制的動(dòng)態(tài)再結(jié)晶，通過(guò)晶界遷移、亞晶合并與轉(zhuǎn)動(dòng)機(jī)制形成細(xì)小的α(Mg)再結(jié)晶等軸晶；隨著往復(fù)擠壓道次的增加，動(dòng)態(tài)再結(jié)晶速度加快，晶粒尺寸迅速減小；α(Mg)與Mg2Si的晶粒尺寸在鑄態(tài)下分別為45和60 µm，往復(fù)擠壓6道次后，晶粒尺寸減小到3和1 µm，形成了細(xì)小、均勻的α(Mg)等軸晶組織，Mg2Si顆粒呈細(xì)小、彌散分布；合金的力學(xué)性能隨往復(fù)擠壓道次的增加而顯著提高。
關(guān)鍵字: Mg-4Al-2Si鎂合金；往復(fù)擠壓；動(dòng)態(tài)再結(jié)晶；力學(xué)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
