| About this Abstract |
| Meeting |
Superalloys 2024
|
| Symposium
|
Superalloys 2024
|
| Presentation Title |
On the Evolution of the γ/γ′ Lattice Misfit and TCP Phase Precipitation in a Highly Alloyed Single Crystalline Ni-base Superalloy |
| Author(s) |
Jakob Bandorf, Anna Kirzinger, Christopher H. Zenk, Hon Tong Pang, Catherine M.F. Rae, Howard J. Stone, Steffen Neumeier |
| On-Site Speaker (Planned) |
Jakob Bandorf |
| Abstract Scope |
Ni-base superalloys of the latest generation are prone to the formation of topologically close-packed (TCP) phases due to their high content of refractory elements. The quantitative correlation between the TCP phase precipitation, the evolution of the lattice parameters, and the γ/γ′ lattice misfit in a highly alloyed single crystal Ni-base superalloy is investigated here. Even in the standard heat-treated state TCP phases are found in the dendrite cores. With additional annealing at 1100 °C further TCP phase precipitation occurs until a constant fraction is reached after 100 h. High-resolution X-ray diffraction experiments conducted at room temperature revealed that the lattice parameter of the γ phase decreases with increasing exposure time and reaches, like the TCP phase fraction, a kind of plateau after long aging durations. In contrast, the lattice parameter of the γ′ phase hardly changes throughout aging, which results in a decrease of the initial γ/γ′ lattice misfit from about -1 % to a plateau of about -0.45 % after 1000 h. Comparison of thermodynamic and lattice parameter calculations with the experimentally determined values revealed that the depletion of the main TCP phase forming elements Re, W and Mo associated with the ongoing TCP phase formation is the main reason for this behavior. It is also shown that the effect of both stress relaxation and TCP phase precipitation results in a reduction of the tetragonal distortion and coherency stresses in the γ matrix channels. |
| Proceedings Inclusion? |
Definite: At-meeting proceedings |