(1. 重庆大学 材料科学与工程学院，重庆 400045；
2. 重庆大学 国家镁合金材料工程技术研究中心，重庆 400044)
摘 要: 研究均匀化、挤压以及热处理对Mg-5.77%Zn-0.94%Mn(ZM61)(质量分数)镁合金显微组织和力学性能的影响。结果表明：ZM61铸态组织呈枝晶结构，枝晶间网状的和枝晶内颗粒状的金属间化合物为Mg7Zn3；经(330 ℃，8 h)+(420 ℃，2 h)的两级均匀化处理后，化合物绝大部分溶解于基体；两级均匀化处理可大幅降低合金的挤压温度(降低幅度30 ℃)、减少挤压态组织中的残余流线、提高挤压态合金的伸长率、缩短固溶时间，但并未明显细化挤压态合金的晶粒；对于可时效强化的ZM61变形镁合金来说，晶粒大小对其力学性能的影响不大，起主要强化作用的是时效析出相的类型、尺寸和弥散程度；ZM61在时效过程中主要析出沿[0001]α-Mg的 杆状相和平行于(0001)α-Mg的 盘状相的析出相，其中 杆状相为起主要强化作用的析出相。
关键字: Mg-5.77%Zn-0.94%Mn(ZM61)合金；均匀化；挤压；固溶处理；时效；析出相
（1. College of Materials Science and Engineering, Chongqing University, Chongqing 400045, China;
2. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400044, China）
Abstract:The effects of homogenization, extrusion and heat treatment on microstructure and mechanical properties of Mg-5.77%Zn-0.94%Mn (ZM61) (mass fraction) Mg alloy were investigated. The results show that the microstructure of the as-cast ZM61 alloy is typical dendrite structure, the interdendritic network intermetallic compounds are Mg7Zn3. The majority of these compounds dissolves into the matrix after (330 ℃, 8 h)+(420 ℃, 2 h) homogenization treatment. Two-step homogenization can significantly decrease the extrusion temperature (decreased by 30 ℃), reduce the residual streamline in microstructure, improve the elongation of as-extruded alloy, and shorten the solution time, but not significantly refine the grain size of the as-extruded alloy. For wrought ZM61 Mg alloy, the precipitates type, size and dispersion degree play the major role in strengthening, the effect of grain size is weak. There are mainly two types of precipitates in as-aged alloy, one is rod-shaped phase along [0001]α-Mg, the other is plate-shaped phase parallel to (0001)α-Mg, and the rod-shaped phase is primarily strengthening precipitates.
Key words: Mg-5.77%Zn-0.94%Mn(ZM61) alloy; homogenization; extrusion; solution treatment; aging; precipitates
