Characterization and Modeling of Microstructure Development in Nickel-base Superalloy Welds
Welding is important for economical reuse and reclamation of used and failed nickel-base superalloy blades, respectively [1]. Solidification and solid state decomposition of {gamma} (Face Centered Cubic, FCC) phase into {gamma}{prime} (L1{sub 2}-ordered) phase control the properties of these welds. In previous publications, the microstructure development in electron beam welds of PWA-1480 alloy [2] and laser beam welds of CMSX-4 alloy [3] were presented. These results showed that the weld cracking in these alloys were associated with low melting point eutectic at the dendrite boundaries [1,2]. The eutectic-{gamma}{prime} precipitation was reduced at rapid weld cooling rates and the partitioning between {gamma}-{gamma}{prime} phase was found to be far from equilibrium conditions [3,4]. This observation was related to diffusional growth of {gamma}{prime} precipitate into {gamma} phase. Subsequent to the above work, the precipitation characteristics of {gamma}{prime} phase from {gamma} phase were evaluated during continuous cooling conditions [5]. The results show that the number density of {gamma} precipitates increased with an increase in cooling rate. However, the details of this decomposition and also the fine-scale elemental partitioning characteristics between {gamma}-{gamma}{prime} were not investigated. In this paper, the precipitation characteristics of {gamma}{prime} from {gamma} during continuous cooling conditions were investigated with transmission electron microscopy, and atom probe field ion microscopy. In addition, thermodynamic and kinetic models were used to describe microstructure development in Ni-base superalloy welds.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (US)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 14979
- Report Number(s):
- ORNL/CP-105232; TRN: AH200130%%195
- Resource Relation:
- Conference: Joining of Advanced and Specialty Materials II, Cincinnati, OH (US), 11/01/1999--11/04/1999; Other Information: PBD: 1 Nov 1999
- Country of Publication:
- United States
- Language:
- English
Similar Records
Microstructural development in PWA-1480 electron beam welds: An atom probe field ion microscopy study
Microstructure Development in Nickel Base Superalloys during Weld Thermal Cycle