Computational modeling of NbC/Laves formation in INCONEL 718 equiaxed castings
- Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Metallurgical and Materials Engineering
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.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 522366
- Journal Information:
- Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Vol. 28, Issue 7; Other Information: PBD: Jul 1997
- Country of Publication:
- United States
- Language:
- English
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