纵向磁场对不同尺寸定向凝固高温合金DZ417G组织的影响  

EFFECT OF LONGITUDINAL MAGNETIC FIELD ON THE MICROSTRUCTURE OF DIRECTIONALLY SOLIDIFIED SUPERALLOY DZ417G WITH DIFFERENT SIZES

作　　者：玄伟东[1] 任忠鸣[1] 李传军[1] 任维丽[1] 陈超[1] 于湛[1] 

机构地区：[1]上海大学上海市现代冶金与材料制备重点实验室,上海200072

出　　处：《金属学报》2012年第5期629-635,共7页Acta Metallurgica Sinica

基　　金：国家重点基础研究项目2011CB610404;国家自然科学基金项目50911130365;上海市科学技术委员会项目08dj1400404和08DZ1130100;中国博士后科学基金项目20110490712资助~~

摘　　要：进行了外加纵向静磁场下高温合金DZ417G的定向凝固实验,考察了纵向磁场对不同尺寸试样凝固组织形貌的影响.结果显示,在温度悌度为70℃/cm,抽拉速率为5μm/s时,施加磁场后一次枝晶间距减小,并在试样边缘出现等轴晶组织;随着试样尺寸的增大,在试样边缘和中心的柱状枝晶组织遭到破坏,形成等轴晶组织,且出现"斑状"偏析.这些现象可归结为磁场在固/液界面前沿合金熔体中诱发的热电磁对流(TEMC)所致.In order to understand the influence of a longitudinal magnetic field on the microstructures of the superalloy DZ417G with different sample sizes,the superalloy DZ417G was directionally solidified under a longitudinal magnetic field.The solidification structures of the alloy with various dimensions of specimen have been investigated.The results showed that the columnar dendrites on the edge of samples were broken and changed into equiaxed dendrites in the magnetic field at the withdrawal velocity of 5μm/s and temperature gradient of 70℃/cm.Additionally,it was found that equiaxed dendrites area expanded from the edge to the center of sample and the number of freckle-like macrosegregation increased with the size of sample.The columnar to equiaxed transition and frecklelike macrosegregation can be attributed to the thermoelectric magnetic convection（TEMC） induced by the magnetic field in the front of solid/liquid interface during directional solidification.

关 键 词：镍基高温合金 磁场 定向凝固 枝晶 热电磁对流 

分 类 号：TG146[一般工业技术—材料科学与工程]