碎化机理及动态析出行为
(1. 太原理工大学 材料科学与工程学院，太原 030024；
2. 太原理工大学 新材料界面科学与工程教育部重点实验室，太原 030024)
摘 要: 为了改善Mg-Al系合金中β-Mg17Al12相的形态、大小和分布，充分发挥其沉淀强化作用，利用能产生强塑性变形的等通道转角挤压法挤压Mg15Al高铝镁合金；采用XRD、SEM、EDS和TEM研究不同道次ECAP挤压后Mg15Al高铝镁合金中β-Mg17Al12相的演变。结果表明：ECAP强塑性变形能够有效地碎化Mg15Al高铝镁合金中粗大的网状共晶β-Mg17Al12相；随挤压道次的增加，β-Mg17Al12相尺寸逐渐减小，挤压4道次后，网状共晶β-Mg17Al12相被破碎成尺寸在5 μm以下的小块，分布得到一定改善；由于高应力与高温的共同作用，挤压2道次后，部分β-Mg17Al12相发生回溶，挤压4道次后，在α-Mg基体中动态析出许多尺寸在200 nm以下的粒状β-Mg17Al12相。
关键字: Mg15Al高铝镁合金; β-Mg17Al12相；碎化机理；动态析出行为
β phase in Mg15Al magnesium alloy during ECAP
（1. College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China;
2. Key Laboratory of Interface Science and Engineering in Advanced Materials, Ministry of Education,
Taiyuan University of Technology, Taiyuan 030024, China）
Abstract:In order to improve the morphology, size and distribution of β-Mg17Al12 phase in the Mg-Al alloy and fulfill the precipitation strengthening effect of β-Mg17Al12 phase, Mg15Al high-aluminum magnesium alloy was processed by equal channel angular pressing. The evolution of β-Mg17Al12 phase in the Mg15Al high-aluminum magnesium alloy after equal channel angular pressing (ECAP) for different passes was investigated by XRD, SEM, EDS and TEM. The results show that the coarse network eutectic β-Mg17Al12 phase in Mg15Al high aluminum-magnesium alloy can be effectively fragmentized by ECAP. With increasing extrusion passes, the size of β-Mg17Al12 decreases. After ECAP for 4 passes, β phase is fragmentized into small lump-shaped particles with size of less than 5 μm and the distribution of β phase becomes more homogeneous. Meanwhile, due to the large shear stress and high temperature, the dissolution of β phase in matrix occurs after ECAP for 2 passes and a large number of granular β phase with the size below 200 nm precipitates from the matrix after ECAP for 4 passes.
Key words: Mg15Al high-aluminum magnesium alloy; β-Mg17Al12 phase; fragmentation mechanism; dynamic precipitation behavior
