Berlin 2008 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 48: Phase Transitions V

MM 48.4: Talk

Friday, February 29, 2008, 11:00–11:15, H 0107

The influence of elastic strain onto the early stage of decomposition in Cu1,7at.%Fe — •Thomas Rademacher, Talaat Al-Kassab, and Reiner Kirchheim — Institut für Materialphysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany

Dilute supersaturated Cu Fe alloys have been previously intensely studied in the course of classical homogeneous phase separation neglecting the influence of the anisotropical character of elastic strain.

In a former study HEINRICH et al. (Mat. Sci. Eng. A353 (2003) 92-98) showed that early stages of decomposition at low temperatures of supersaturated Cu Co alloys is mainly controlled by such strain energy. It governs the cluster's size and morphology. It also promotes the formation of chains of precipitates in the elastic soft <100> directions of the Cu-matrix which is in agreement with calculations by MIYASAKI and YAMAUCHI/DE FONTAINE in framework of linear anisotropic elasticity theory. In the current study, these phenomena will be discussed for Cu1,7at%Fe after a heat treatment at 722 K for times ranging from 1,5 to 168 hours. Atom Probe Tomography (APT) was used for measurements as well as the newly developed computer assisted Field Ion Image Tomography (cFIIT) involving an improved reconstruction algorithm which will be presented in short.

Chain like formation of precipitates can be observed. Furthermore the precipitates' positions are systematically determined by computer algorithms and additionally analysed for their relative positions. A preferential alignment in <100> directions can be shown which implies a contribution of the elastic strain on the decomposition behaviour.