Atom probe field-ion microscopy investigation of nickel base superalloy welds
Microstructure development and elemental partitioning between {gamma} and {gamma}{prime} were measured in PWA-1480 electron beam welds and CMSX-4 pulsed-laser welds. In PWA-1480 EB welds, eutectic {gamma}{prime} phases were observed along the dendritic boundaries. The elemental partitioning between {gamma} and {gamma}{prime} was found to be similar to that in PWA-1480 base metal. In CMSX-4 pulsed laser welds, negligible eutectic {gamma}{prime} was observed. In addition, fine and irregularly shaped {gamma}{prime} precipitates were observed. The elemental partitioning between {gamma} and {gamma}{prime} was found to be different from that measured in the base metal. Large concentration gradients were observed in the {gamma} phase. The {gamma}{prime} precipitation kinetics in CM247DS alloy was measured using dilatometry and showed differences with different cooling rates. The microstructural investigations showed that at large undercoolings the number density of {gamma}{prime} precipitates increased and led to a finer size. This supports the microstructure development observations in PWA-1480 and CMSX-4 welds. Thermodynamic and kinetic calculations for the Ni-Al-Cr alloy system showed that as the cooling rate increases, the {gamma}{prime} growth leads to large concentration gradients in the {gamma} phase. The calculations agree with the atom probe results from PWA-1480 and CMSX-4 welds.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 290932
- Report Number(s):
- ORNL/CP-99118; CONF-980657-; ON: DE99000218; BR: KC0201050; KC0201010; TRN: AHC29901%%137
- Resource Relation:
- Conference: 5. international conference on trends in welding research, Pine Mountain, GA (United States), 1-5 Jun 1998; Other Information: PBD: [1998]
- Country of Publication:
- United States
- Language:
- English
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