Formation of Nb-rich droplets in laser deposited Ni-matrix microstructures

Published

March 15, 2018

Author(s)

Supriyo Ghosh, Mark R. Stoudt, Lyle E. Levine, Jonathan E. Guyer

Abstract

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.

Citation

Scripta Materialia

Volume

146

Pub Type

Journals

Download Paper

https://doi.org/10.1016/j.scriptamat.2017.10.034

Local Download

Keywords

Additive manufacturing, Finite element, Phase-field, Cells, Droplets, Laves phase

Citation

Ghosh, S. , Stoudt, M. , Levine, L. and Guyer, J. (2018), 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 December 11, 2024)