Correlative analysis of grain boundary precipitates in Ni-based superalloy René 41

Autor: R. Buerstmayr, M. Lison-Pick, Richard F. Webster, Felix Theska, Sophie Primig
Rok vydání: 2021
Předmět:
Zdroj: Materials Characterization. 178:111250
ISSN: 1044-5803
Popis: Both hot workability and in-service mechanical properties of Ni-based superalloys are strongly influenced by the presence of secondary phases precipitated within the matrix and at grain boundaries. Due to its remarkably high contents of alloying elements, Ni-based superalloy Rene 41 forms various precipitate phases at grain boundaries, including but not limited to various carbides and γ’ precipitates, and this may lead to grain boundary cracking. Better knowledge of the nature of these precipitates at different temperatures will enable manufacturing of Rene 41 aerospace parts with higher yield and better in-service properties. Limitations of conventional electron microscopy methods have previously impeded progress at this front. Previous studies on grain boundary precipitation in Rene 41 indicate the co-existence of two dominant types of grain boundary carbides, M6C at temperatures up to 1147 °C and M23C6 below 980 °C. However, recent state-of-the-art thermodynamic simulations indicate that M6C is stable over a much wider temperature range. We propose a novel correlative approach using both convergent beam electron diffraction (CBED) and site-specific atom probe microscopy (APM) to distinguish grain boundary carbides in Rene 41 unambiguously. While CBED reveals space groups, APM enables chemical analyses with near atomic resolution in 3D. Our correlative microscopy combined with thermodynamic simulations confirms the presence of both M6C and M23C6 after annealing at 900 °C while only M6C is present at 1100 °C.
Databáze: OpenAIRE
Externí odkaz: