Regensburg 2016 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 26: Poster session II

MM 26.7: Poster

Dienstag, 8. März 2016, 18:30–20:30, Poster B3

Assessing phase stability and element distribution in Co-base superalloys at elevated temperatures by in situ TEM heating experiments. — •Yolita Eggeler, Julian Müller, and Erdmann Spiecker — Lehrstuhl für Mikro- und Nanostrukturforschung & Center for Nanoanalysis and Electron Microscopy (CENEM), Department Werkstoffwissenschaften, Universität Erlangen-Nürnberg, Cauerstraße 6, 91058 Erlangen

Co-based alloys, of a composition of Co-12Al-9W, form a stable two phase γ/γ' microstructure at 900 °C [1]. γ' cubes, consisting of the L12 crystal structure are coherently embedded in a solid solution fcc (A1) γ matrix. To ensure precipitate hardening at temperatures, which are relevant to practical applications, 700-1100 °C, as experienced in gas turbine applications, the stability of the γ/γ' phases is of fundamental importance. In this analysis in situ TEM studies with chip-based heating systems (by DENS solution) are applied on new Co-based superalloys. After in situ heating at apr. 900 °C and controlled quenching with different quenching rates the elemental distribution at the γ/γ' interface is measured using ChemiSTEM EDX. Exploiting the driving force for interface movement resulting from temperature-dependent volume fraction of γ and γ' insight into the diffusion of individual alloying elements and the relationship between local chemistry and ordering can be gained from transient phenomena. The experimental results will be compared with theoretical calulations. This work has been carried out within the framework of the SFB-TR 103 "Single Crystal Superalloys". [1] J. Sato et al, Science (2006), vol.312, p. 90