Berlin 2012 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 17: Poster Session

MM 17.49: Poster

Montag, 26. März 2012, 17:00–19:00, Poster B

Compositional changes during phase separation of γ′ precipitates in a Ni-Al-Ti model alloy — •Florian Vogel, Nelia Wanderka, and John Banhart — Helmholtz Zentrum Berlin GmbH, Hahn-Meitner-Platz 1, 14109 Berlin, Germany

The phase-separation phenomenon of γ′ precipitates in a single crystal Ni-8.5Al-5.4Ti (at.%) model alloy was investigated by means of transmission electron microscopy (TEM) and three-dimensional atom probe (3D-AP). After homogenization, ageing at 1213 K led to formation of the initial γ/γ′ microstructure composed of cuboidal γ′ precipitates embedded in a γ matrix. Subsequent ageing at 1023 K resulted in the formation of new particles within the γ′ precipitates. Ex-situ TEM was used to follow the influence of these particles on the evolution of microstructure and the kinetics of γ′ coarsening. 3D-AP revealed the chemical composition of the γ matrix, the γ′ precipitates and the particles within γ′. It was found that the particles are rich in Ni and poor in Ti as compared to the γ′ precipitates. The results are discussed with respect to the solubility of Ni within the γ′ phase based on heat treatment conditions.