(1. 河南理工大學(xué) 材料科學(xué)與工程學(xué)院，焦作 454000；
2. 河南理工大學(xué) 機(jī)械與動力工程學(xué)院，焦作 454000；
3. 河南理工大學(xué) 文法學(xué)院，焦作 454000)
摘 要: 研究擠壓溫度、擠壓速度及道次對鑄態(tài)Mg-5Sn-1.5Al-1Zn-1Si合金顯微組織的影響。結(jié)果表明：合金顯微組織的均勻性隨著擠壓溫度的升高表現(xiàn)出先提高后降低的趨勢。當(dāng)溫度較低時，動態(tài)再結(jié)晶過程緩慢，晶粒尺寸不均勻；當(dāng)溫度較高時，動態(tài)再結(jié)晶過程速度加快，晶粒較粗大。晶粒尺寸隨著擠壓速度的增加表現(xiàn)出先減小后增大的趨勢，速度較小或較大均會造成合金顯微組織的不均勻。當(dāng)擠壓速度較小時，容易出現(xiàn)二次再結(jié)晶過程；當(dāng)擠壓速度較大時，再結(jié)晶過程不充分。隨著擠壓道次的增加，合金顯微組織的均勻性逐漸提高，晶粒尺寸表現(xiàn)出先減小后增大的趨勢。往復(fù)擠壓超過7道次后，晶粒細(xì)化效果減弱，合金顯微組織中重新出現(xiàn)大尺寸的晶粒，位錯組態(tài)由位錯墻向位錯胞轉(zhuǎn)化。
關(guān)鍵字: 鎂合金；往復(fù)擠壓；工藝參數(shù)；組織演變
（1. Institute of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China;
2. Institute of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo 454000, China;
3. Institute of Liberal Arts and Law, Henan Polytechnic University, Jiaozuo 454000, China）
Abstract:The effects of extrusion temperature, extrusion speed and extrusion passes on microstructure of the as-cast Mg-5Sn-1.5Al-1Zn-1Si magnesium alloy were studied. The results indicate that the uniformity of alloy microstructure increases firstly, and then reduces with the increase of extrusion temperature. When temperature is lower, the dynamic recrystallization is slow and the grain sizes are uneven; when the temperature is higher, the dynamic recrystallization process is accelerating and grains are coarse. With the increase of extrusion speed, the grain size decreases firstly and then increases, a slower or faster extrusion speed will cause inhomogeneous distribution of the microstructure. When the extrusion speed is slower, the secondary recrystallization processes occur easily, while the faster extrusion speed causes insufficiency of recrystallization process. With the increase of extrusion passes, the microstructure uniformity improves gradually and the grain size decreases firstly and then increases. After reciprocating extrusion (REX) for more than 7 passes, the refining effect becomes weaken and large grains appear in the microstructure again, and the dislocation configuration transforms from dislocation walls to dislocation cells.
Key words: magnesium alloy; reciprocating extrusion; technological parameter; microstructure evolution
