碎化機(jī)理及動(dòng)態(tài)析出行為
(1. 太原理工大學(xué) 材料科學(xué)與工程學(xué)院，太原 030024；
2. 太原理工大學(xué) 新材料界面科學(xué)與工程教育部重點(diǎn)實(shí)驗(yàn)室，太原 030024)
摘 要: 為了改善Mg-Al系合金中β-Mg17Al12相的形態(tài)、大小和分布，充分發(fā)揮其沉淀強(qiáng)化作用，利用能產(chǎn)生強(qiáng)塑性變形的等通道轉(zhuǎn)角擠壓法擠壓Mg15Al高鋁鎂合金；采用XRD、SEM、EDS和TEM研究不同道次ECAP擠壓后Mg15Al高鋁鎂合金中β-Mg17Al12相的演變。結(jié)果表明：ECAP強(qiáng)塑性變形能夠有效地碎化Mg15Al高鋁鎂合金中粗大的網(wǎng)狀共晶β-Mg17Al12相；隨擠壓道次的增加，β-Mg17Al12相尺寸逐漸減小，擠壓4道次后，網(wǎng)狀共晶β-Mg17Al12相被破碎成尺寸在5 μm以下的小塊，分布得到一定改善；由于高應(yīng)力與高溫的共同作用，擠壓2道次后，部分β-Mg17Al12相發(fā)生回溶，擠壓4道次后，在α-Mg基體中動(dòng)態(tài)析出許多尺寸在200 nm以下的粒狀β-Mg17Al12相。
關(guān)鍵字: Mg15Al高鋁鎂合金; β-Mg17Al12相；碎化機(jī)理；動(dòng)態(tài)析出行為
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
