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

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.