一种柱状晶辅助选晶制备镍基单晶高温合金的方法

A Novel Grain Selection Method Assisted by Columnar Grains for Ni-based Single Crystal Superalloy

摘要: 提出了一种采用柱状晶辅助选晶的制备镍基单晶高温合金的方法。采用金相显微镜和电子背散射衍射（EBSD）等方法表征了单晶制备过程中显微组织及晶体取向。结果表明：柱状晶部分熔化，柱状晶边缘回熔界面附近形成大量杂晶，但只有<001>方向偏离定向凝固方向较小的晶粒能够长大。采用柱状晶选晶的方法能够在螺旋选晶器出口处获得<001>方向偏离定向凝固方向小于8°的单晶铸件。

Abstract: A novel grain selection method assisted by columnar grains for controlling the orientation of Ni-based single crystal was proposed in this paper. The microstructure and crystal orientation were characterized by metallographic microscope and electron backscatter diffraction (EBSD). The columnar grains partially melted, and a large number of stray grains formed near the melt back region. Only the epitaxial growth grains along the un-melted columnar grains grew up in the process of competitive growth. The <001> direction of grain selected by this method limited within 8 degree deviating from directional solidification.