强制对流搅拌流变压铸AZ91D镁合金的组织与性能  

MICROSTRUCTURES AND PROPERTIES OF AZ91D MAGNESIUM ALLOY PRODUCED BY FORCED CONVECTION MIXING RHEO-DIECASTING PROCESS

作　　者：祁明凡 康永林[1] 周冰[1] 朱国明[1] 张欢欢[1] 

机构地区：[1]北京科技大学材料科学与工程学院,北京100083

出　　处：《金属学报》2015年第6期668-676,共9页Acta Metallurgica Sinica

基　　金：国家重点基础研究发展计划项目2011CB606302;国家高技术研究发展计划项目2013AA031001~~

摘　　要：依据强制对流搅拌原理,成功自主研制出强制对流搅拌(FCM)制浆设备,并与压铸机相结合,以AZ91D镁合金力学拉伸件为例,实现了浆料制备、输送到成形的一体化流变压铸过程;研究了不同FCM工艺参数下流变压铸件组织特征的演变;对比了不同工艺下压铸件力学性能的差异;并分析了FCM流变压铸工艺组织形成机理及凝固行为.结果表明:FCM工艺参数对铸件的显微组织有较大影响,适当提高螺杆转速或降低筒体温度,均有利于成形件组织形貌的改善;FCM流变压铸工艺不仅可以获得内部组织细小、圆整且分布均匀的成形件,而且可以显著提高成形件的力学性能;与传统压铸件相比,FCM流变压铸件的屈服强度变化不大,抗拉强度和延伸率分别提高了12.5%和80.0%;与经T4和T6热处理的铸件相比,铸态拉伸件的抗拉强度最低,屈服强度和伸长率介于T4和T6之间.Based on the forced convection mixing （FCM） principle, a self-developed FCM semisolid slurry preparation device was successfully developed. Taking AZ91D magnesium alloy tensile parts for example, the rheo-diecasting process that consists of slurry preparation, transportation and forming was achieved by combining with a diecasting machine. Microstructural characteristics of FCM rheo-diecasting parts in different processing parameters were investigated. Mechanical properties of AZ91D alloy parts in different processes were compared. Besides, the formation mechanism and solidification behavior of semisolid slurry were analyzed in FCM rheo-diecasting process. The results show that processing parameters have a great effect on the microstmctures of parts, increasing rotation speed or decreasing barrel temperature appropriately is beneficial to optimizing the microstructure. The process not only can produce parts with fine, spherical and uniformly distributed primary a-Mg particles, but also is able to improve mechanical performance of parts significantly. Compared with traditional diecasting, the yield strength remains unchanged, but the ultimate strength and elongation are increased by 12.5% and 80.0%, respectively. Furthermore, compared with parts subjected to T4 and T6 heat treatment, the ultimate strength of the as-cast is the lowest, and the yield strength and elongation are between T4 and T6.

关 键 词：AZ91D镁合金 强制对流搅拌 流变压铸 组织演变 力学性能 热处理 

分 类 号：TG146.2[一般工业技术—材料科学与工程]