高温合金单晶铸件中条纹晶缺陷的试验研究  

Study on Sliver Defects in Single Crystal Castings of Superalloys

作　　者：马德新 王富[3] 孙洪元 徐维台 MA De-xin;WANG Fu;SUN Hong-yuan;XU Wei-tai(Wedge Central South Research Institute,Shenzhen 518045,Guangdong,China;Central South University,Changsha 410083,Hunan,China;Xi'an Jiao Tong University,Xi'an710049,Shaanxi,China)

机构地区：[1]深圳万泽中南研究院,广东深圳518045 [2]中南大学,湖南长沙410083 [3]西安交通大学,陕西西安710049

出　　处：《铸造》2019年第6期558-566,共9页Foundry

基　　金：广东省引进创新创业团队项目(607264877417);深圳科技创新委员会项目(20170308111659935)。

摘　　要：对几种高温合金铸件中的条纹晶缺陷进行了考察和分析。发现条纹晶多出现于竖直的叶身部位,叶背多于叶盆,上部多于下部,而叶根(榫头)部位极少出现。在竖直的叶身部位的条纹晶多是纵向生长,但也有的是斜向发展。而处于水平状态的叶冠或缘板上会出现横向的条纹晶缺陷。所有条纹晶都是在基体枝晶组织的基础上形成,其基本走向由基体枝晶决定,不论这些枝晶是纵向、斜向还是横向。条纹晶不仅是是细长的线形缺陷,也可能发展为大尺度的三维缺陷,严重影响单晶铸件的质量。从铸件的微观组织来看,条纹晶实际上起源于单晶基体上断裂出来的一段枝晶。This paper presents the observations on the sliver defects in the single crystal (SC) castings of some Ni-based superalloys. It was found that the slivers occurred most frequently on the blade bodies, especially on their convex sides and upper positions. In comparison, fewer slivers were observed in blade foot. Beside the vertical ones, tilted slivers were also observed. On the horizontally positioned platforms, however, lateral slivers were formed because of the matrix dendrites grown in the same direction. That means the alignment of the slivers is not always along the axis of the blades, but determined by the orientation of the local matrix dendrites, no matter it is vertical, tilted or lateral. Sometimes a narrow sliver can develop into 3-dementional defect of large scale, hence becoming a serious grain defect in SC casting. In the metallographic detection, sliver grain can be identified to be mis-alignments of isolated, individual primary dendrite stems on the SC matrix. The mechanism of sliver formation should be further studied in the next work.

关 键 词：高温合金 单晶 定向凝固 条纹晶 晶体缺陷 

分 类 号：TG172[金属学及工艺—金属表面处理]