Computational Modeling and Experimental Validation of Microstructural Development in Superalloy CMSx-4 Processed through Scanning Laser Epitaxy

This paper focuses on computational modeling of Scanning Laser Epitaxy (SLE), an additive manufacturing technology being developed at Georgia Tech for the creation of equiaxed, directionally-solidified or single-crystal structures in nickel-based superalloys. The thermal modeling of the system, carried out in a commercial CFD software package, simulates a heat source moving over a powder bed and dynamically adjusts the property values for consolidating CMSX-4 alloy powder. For any given position of the beam, the geometrical parameters of and the temperature gradient in the melt pool are used to estimate the resulting solidification microstructure. Detailed study of the flow field also revealed formation of rotational vortices in the melt pool. Microstructural predictions are shown to be in good agreement with experimental metallography. This work is sponsored by the Office of Naval Research through grant N00014-11-1-0670.