Evolution of local misorientations in the γ/γ'-microstructure of single crystal superalloys during creep studied with the rotation vector baseline (RVB) EBSD method

0579198 - ÚFM 2025 RIV US eng J - Článek v odborném periodiku
Gamanov, Štěpán - Dlouhý, Antonín - Bürger, D. - Eggeler, G. - Thome, P.
Evolution of local misorientations in the γ/γ'-microstructure of single crystal superalloys during creep studied with the rotation vector baseline (RVB) EBSD method.
Microscopy Research and Technique. Roč. 87, č. 3 (2024), s. 516-533. ISSN 1059-910X. E-ISSN 1097-0029
Institucionální podpora: RVO:68081723
Klíčová slova: interfacial dislocation networks * temperature * deformation * misfit * stress * local dislocation densities * misorientations between gamma and gamma' phases * rotation vector baseline EBSD method * scanning transmission electron microscopy * single crystal Ni-base superalloys
Obor OECD: Materials engineering
Impakt faktor: 2.5, rok: 2022
Způsob publikování: Open access
https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/10.1002/jemt.24453

The present work uses the rotation vector baseline electron back scatter orientation imaging method (RVB-EBSD) to study the evolution of small misorientations between the gamma- and gamma'-phase in Ni-base single crystal superalloys (SXs) during creep. For this purpose, two material states of the SX ERBO1 (CMSX4 type) were characterized after creep deformation at 850 degrees C and 600 MPa to final strains of 1% and 2%. Obtaining reliable phase boundary misorientation (PBM), kernel average misorientation (KAM) and orientation spread (OS) data represents a challenge for electron backscatter diffraction (EBSD), not only because the method operates at its limits of lateral and angular resolution, but also because it is difficult to differentiate between the two phases merely based on Kikuchi diffraction. The two phases differ in chemical composition which gives rise to different EBSD background intensities. These can be exploited to differentiate between the two phases. In the present work, crystallographic and chemical information are combined to demonstrate that orientation imaging can be used to document the formation of dislocation networks at gamma/gamma'-interfaces and the filling of gamma-channels by dislocations. These findings are in good agreement with reference results from diffraction contrast scanning transmission electron microscopy. It is also shown that misorientations evolve between small groups of equally oriented gamma/gamma'-neighborhoods, on a size scale above characteristic gamma/gamma'-dimensions (>0.5 mu m) and below distances associated with dendritic mosaicity (<200 mu m). The methodological aspects as well as the new material specific results are discussed in the light of previous work published in the literature.
Trvalý link: https://hdl.handle.net/11104/0352715