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MM: Fachverband Metall- und Materialphysik

MM 20: Poster Session I

MM 20.6: Poster

Dienstag, 24. März 2009, 14:45–16:30, P4

Characterization of the Brittle-to-Ductile Transition in NiAl Single Crystals — •Michael Scharnweber, Carl-Georg Oertel, and Werner Skrotzki — Institut für Strukturphysik, Technische Universität Dresden, 01062 Dresden

Hard oriented NiAl single crystals (<100> deformation axis) have been deformed in compression above and below the Brittle-to-Ductile Transition Temperature (BDTT). The investigation of slip lines suggests a smooth transition from {112}<111> slip at 550 K to {110}<110> slip at 620 K. However, the results of the compression experiments reveal a rather sharp transition in the temperature range 645 K - 655 K. Below the BDTT an anomalous temperature dependence of the yield stress was observed. The activation enthalpy measured supports the deformation model given by Mills et al. [1] suggested for {110}<110> slip. For comparison, soft oriented single crystals (<110> deformation axis) have been deformed in the same temperature range. The active slip system found was {100}<100> with the faint slip line pattern indicating cross slip. For <110> orientation in the whole temperature range investigated the yield stress decreases with increasing temperature.

[1] M.J. Mills, R. Srinivasan, M.S. Daw, Phil. Mag. A, 77, 801 (1998)