|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Materials for High Temperature Applications: Next Generation Superalloys and Beyond
||Atom Probe Tomography Study of Sigma Phase in Long Term-thermally Exposed High Refractory Ni-based Superalloy
||Stoichko Antonov, Jiajie Huo, Qiang Feng, Dieter Isheim, David N. Seidman, Sammy Tin
|On-Site Speaker (Planned)
In polycrystalline Ni-base superalloys, grain boundary precipitation of secondary phases can be very important due to the effects they pose on the mechanical properties. Furthermore due to the nature of TCP phases, other properties such as oxidation and corrosion resistance can also be negatively affected. Long term thermal exposures on an experimental powder processed Ni-base superalloys containing elevated levels of Nb was completed to assess the precipitation kinetics and thermodynamic stability of Cr,Mo-rich sigma phase precipitates. Atom probe tomography was used to evaluate the composition profiles of the sigma and the surrounding γ’ phases, as well as to study any interfacial segregation and compositional gradients that might exist between the two phases. In addition, TEM was used to confirm the sigma crystal structure and orientation relationship with the matrix. Results of the study will be presented and compared to thermodynamic calculations of the sigma phase composition.