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Title: Computational modeling of NbC/Laves formation in INCONEL 718 equiaxed castings

Abstract

The goal of this work is to develop a solidification kinetics model for prediction of NbC and Laves phase evolution during casting solidification. Previous studies on alloy 718 showed that both NbC and Laves produce intergranular liquid films due to the intergranular distribution of Nb and C. Also, the ability of Laves to promote intergranular liquation cracking (microfissuring and hot cracking) during heat treatment is much higher than that of NbC. This is because the temperature of Laves phase formation is usually lower than that of NbC, i.e., liquation initiates at the eutectic-Laves temperature. Experimental evidence demonstrates that the amount of NbC and Laves in cast alloy 718 is different from that predicted by phase equilibrium. The reason for this difference is that while in equilibrium processes mass diffusion transport is very fast compared with solidification kinetics (V {much_lt} D/L), in casting processes, solidification kinetics is much closer to diffusivity (V {le} D/L). Thus, solidification kinetics cannot be ignored.

Authors:
;  [1]
  1. Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Metallurgical and Materials Engineering
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
522366
Resource Type:
Journal Article
Journal Name:
Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science
Additional Journal Information:
Journal Volume: 28; Journal Issue: 7; Other Information: PBD: Jul 1997
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; MICROSTRUCTURE; SOLIDIFICATION; INCONEL 718; MATHEMATICAL MODELS; NIOBIUM CARBIDES; LAVES PHASES; KINETICS; LIQUID METALS; PREDICTION EQUATIONS; VALIDATION; THEORETICAL DATA; EXPERIMENTAL DATA

Citation Formats

Nastac, L, and Stefanescu, D M. Computational modeling of NbC/Laves formation in INCONEL 718 equiaxed castings. United States: N. p., 1997. Web. doi:10.1007/s11661-997-0220-5.
Nastac, L, & Stefanescu, D M. Computational modeling of NbC/Laves formation in INCONEL 718 equiaxed castings. United States. https://doi.org/10.1007/s11661-997-0220-5
Nastac, L, and Stefanescu, D M. 1997. "Computational modeling of NbC/Laves formation in INCONEL 718 equiaxed castings". United States. https://doi.org/10.1007/s11661-997-0220-5.
@article{osti_522366,
title = {Computational modeling of NbC/Laves formation in INCONEL 718 equiaxed castings},
author = {Nastac, L and Stefanescu, D M},
abstractNote = {The goal of this work is to develop a solidification kinetics model for prediction of NbC and Laves phase evolution during casting solidification. Previous studies on alloy 718 showed that both NbC and Laves produce intergranular liquid films due to the intergranular distribution of Nb and C. Also, the ability of Laves to promote intergranular liquation cracking (microfissuring and hot cracking) during heat treatment is much higher than that of NbC. This is because the temperature of Laves phase formation is usually lower than that of NbC, i.e., liquation initiates at the eutectic-Laves temperature. Experimental evidence demonstrates that the amount of NbC and Laves in cast alloy 718 is different from that predicted by phase equilibrium. The reason for this difference is that while in equilibrium processes mass diffusion transport is very fast compared with solidification kinetics (V {much_lt} D/L), in casting processes, solidification kinetics is much closer to diffusivity (V {le} D/L). Thus, solidification kinetics cannot be ignored.},
doi = {10.1007/s11661-997-0220-5},
url = {https://www.osti.gov/biblio/522366}, journal = {Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science},
number = 7,
volume = 28,
place = {United States},
year = {Tue Jul 01 00:00:00 EDT 1997},
month = {Tue Jul 01 00:00:00 EDT 1997}
}