Formation of Nb-rich droplets in laser deposited Ni-matrix microstructures
Supriyo Ghosh, Mark R. Stoudt, Lyle E. Levine, Jonathan E. Guyer
Ni-rich $\gamma$ cells/dendrites and Nb-rich eutectic droplets that form during laser power bed fusion (LPBF) solidification of Ni-Nb alloys are studied in the present work using numerical simulations. Finite element simulations estimate the local cooling rates in the LPBF melt pool and phase-field simulations predict the resulting cellular microstructures. The cell and droplet spacings are extracted from the simulated microstructures as a function of cooling rate and fit to a power law. The formation of Laves phase is predicted for a critical composition of Nb in the liquid droplets. We find that the cell/droplet spacing as well as the Laves fraction decrease with increasing cooling rate. Our simulations show that the orientation of the primary $\gamma$ phase influences the Laves fraction. The simulated microstructures are supported by preliminary experimental observations of the as-deposited microstructures.
, Stoudt, M.
, Levine, L.
and Guyer, J.
Formation of Nb-rich droplets in laser deposited Ni-matrix microstructures, Scripta Materialia, [online], https://doi.org/10.1016/j.scriptamat.2017.10.034, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=924117
(Accessed October 26, 2021)