大尺寸变截面单晶的枝晶生长行为与杂晶控制

项目名称： 大尺寸变截面单晶的枝晶生长行为与杂晶控制

项目编号： No.51204156

项目类型： 青年科学基金项目

立项/批准年度： 2013

项目学科： 冶金与矿业学科

项目作者： 孟祥斌

作者单位： 中国科学院金属研究所

项目金额： 25万元

中文摘要： 大尺寸变截面缘板的单晶生长技术和杂晶控制技术是制备单晶叶片的核心技术。前期研究结果表明，缘板的尺寸效应对枝晶生长和杂晶形成有重要影响，而这种尺寸效应与不同尺寸的缘板中温度场的演化过程密切相关。本项目拟在已有的工作基础上，以具有重大应用背景的第二代含Re单晶高温合金及变截面单晶试样为研究对象，采用实验和数值模拟相结合的方法，通过对大尺寸变截面单晶高温合金的枝晶生长行为的研究，揭示单晶在变截面处枝晶生长行为、组织演化特征，探讨变截面尺寸效应与枝晶生长行为及杂晶形成的协同作用关系，从微观尺度和介观尺度分别阐明杂晶等凝固缺陷的形成机理。在此基础上，建立杂晶等凝固缺陷与变截面尺寸、工艺参数间的响应关系，提出适合不同尺寸变截面单晶生长的凝固工艺参数和杂晶控制策略，为今后制备具有复杂几何结构的单晶叶片提供理论指导和技术支持。

中文关键词： 定向凝固；Ni基单晶高温合金；杂晶；辅助系统；

英文摘要： Growth of single crystal and inhibition of stray grains in the large dimensional platform are the most important technologies during the production of single crystal turbine blade. In our previous study, it was shown that the platform dimension had significant influence on the dendrite growth and stray grain formation, which was associated with the different evolutions of thermal condition in these different dimensional platforms. Based on these results, in present study, a typical second generation Ni-base superalloy was used, and a model of typical turbine blade shape with different platforms was designed. The behavior of dendrite growth and the formation of stray grains in the platforms with different dimension were studied by both experimental investigation and a ProCAST simulation based on a Cellular Automaton Finite Element (CAFE) model. According to these results, the effect of platform dimension on the dendrite growth and the stray grain formation and the mechanism of the stray grains formation on the microscopic and mesoscopic scale were examined. Furthermore, the formation of stray grains in response to platform dimension and solidification condition was investigated to propose a effective method to produce single crystal without stray grains in the model with different platforms. These results aim at

英文关键词： Directional solidification；Ni-base superalloy；Stray grain；Assistant bars；