Investigation on Orientation Control of Single Crystal Blades Through a Using of Heterogeneous Seeds

As the increasing demand for high temperature performance of the Ni-based single crystal blades, the orientation consistency of the blades has become more and more important. In this work, Ni-W heterogeneous seed was used to prepare the Ni-based single crystal superalloys and the microstructure at remelting interface under different conditions was analyzed. The results showed that lots of fine cellular grains with the basically consistent orientations and compositions were existed in front of the remelting interface under the high-rate solidification (HRS) method, while was not happened under the liquid metal cooling (LMC) condition. Based on the calculation of the constitutional undercooling, it was proved that the HRS method with a small temperature gradient could produce an enough constitutional undercooling at the front of remelting interface to form fine cellular grains. At last, using the heterogeneous seeds, four single crystal blades with the same three-dimensional orientation were successfully produced, which fully improved the preparation efficiencies and orientation quality of the blades, proving the possibility of industrial application for heterogeneous seeds.