(1. 河南理工大學 材料科學與工程學院，焦作 454000；
2. 河南理工大學 經濟管理學院，焦作 454000)
摘 要: 利用往復擠壓在300~360 ℃細化鑄態(tài)Mg-6Zn-1Y-1Ce合金組織，研究其組織演變和擠壓參數(shù)對再結晶組織的影響。結果表明：往復擠壓合金橫截面邊緣存在不均勻環(huán)，由靠近筒壁的細晶環(huán)和粗晶環(huán)組成，其寬度隨著擠壓溫度提高而減小；細晶環(huán)是由邊緣區(qū)域與擠壓筒壁摩擦而發(fā)生第二輪再結晶所致，粗晶環(huán)是由再結晶晶粒長大所致；合金晶粒度由變形速率和溫度決定，經340 ℃擠壓合金晶粒最細，平均粒徑8.2 μm。除邊緣外，往復擠壓過程中合金在擠壓階段發(fā)生一次再結晶，墩粗過程和后續(xù)多道次擠壓變形都是通過晶界滑移實現(xiàn)。因此，隨著擠壓道次的增加，保溫時間隨之延長，晶粒隨之被粗化。
關鍵字: 鎂合金；往復擠壓；再結晶；擠壓參數(shù)
（1. School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China;
2. School of Economic and Management, Henan Polytechnic University, Jiaozuo 454000, China）
Abstract:The microstructure of as-cast Mg-6Zn-1Y-1Ce alloy was refined by reciprocating extrusion (REX) at the temperature range of 300-360 ℃, the microstructural evolution and the effect of extrusion parameters on recrystallized microstructure were investigated. The results show that the as-REXed alloys have an inhomogeneous ring on cross section, which consists of a fine-grain ring and a coarse-grain ring on the periphery. The width of the ring decreases with increasing the extrusion temperature. The fine-grain ring is attributed to the secondary recrystallization occurring because of friction between the periphery of sample and container wall, the coarse-grain ring is attributed to grain growth followed recrystallization. The grain size of REXed alloy is determined by deformation rate and temperature, a minimum grain size of 8.2 μm is obtained at 340 ℃. During REX process, recrystallization occurs only once during extrusion except for the periphery, the deformation processes during upsetting and subsequent multi-pass REX are achieved by grain boundary sliding. Therefore, with increasing REX passes, the holding-time is prolonged and grains coarsen.
Key words: magnesium alloy; reciprocating extrusion; recrystallization; extrusion parameter
