Near Single-Crystalline CMSX-4 Superalloy Builds with Laser-Directed Energy Deposition (L-DED) Using Model-Informed Experiments

Manufacturing of single-crystalline Ni-base superalloy blades is extremely complex due to the intricate geometry of the blade profile and cooling channels. Additive manufacturing provides an excellent alternative to the classical Bridgman solidification, as it significantly reduces the number of steps involved. However, since the solidification conditions differ greatly, it is crucial to identify appropriate process parameters to ensure defect-free single-crystalline builds. In this paper, we present a complementary approach between experiments and numerical simulations of the melt pool shapes that enables the identification of the process parameter window for directional growth. Further, an incremental process optimization approach is developed that allows the gradual reduction of grains, creating conditions for epitaxial growth. Finally, it is revealed that the proposed strategy for achieving single-crystal growth conditions leads naturally towards crack-free builds of rods with the CMSX-4 alloy.