Solidification modeling of Nb bearing superalloys
- Lehigh Univ., Bethlehem, PA (United States)
- Sandia National Labs., Albuquerque, NM (United States)
The solidification behavior of experimental Ni base and Fe base superalloys containing Nb, Si, and C was studied using differential thermal analysis (DTA) and microstructural characterization techniques. The solidification reaction sequences responsible for microstructural development were found to be similar to those expected in the Ni-Nb-C ternary system, where the solute-rich interdendritic liquid exhibited two eutectic-type reactions at the terminal stages of solidification: L {yields} ({gamma} + NbC) and L {yields} ({gamma} + Laves). A pseudo ternary {gamma}-Nb-C approach was developed to provide a quantitative description of solidification behavior for these experimental alloys. Solute redistribution calculations in the model are based on a previous approach developed by Mehrabian and Flemings, with modifications made to account for the high diffusion rate of C in the solid. Solidification parameters for Nb and C were determined through DTA and electron probe microanalysis techniques and used as inputs to the model. Reasonable agreement is found between calculated volume fractions of the {gamma}/NbC and {gamma}/Laves constituents and those measured experimentally. The modeling results permit detailed descriptions of the relation between alloy composition and microstructural evolution during solidification.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 515586
- Report Number(s):
- SAND-97-1669C; CONF-970605-3; ON: DE97007150; TRN: AHC29718%%101
- Resource Relation:
- Conference: 4. international special emphasis symposium on superalloys 718, 625, 706 and derivatives, Pittsburgh, PA (United States), 15-18 Jun 1997; Other Information: PBD: [1997]
- Country of Publication:
- United States
- Language:
- English
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