Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 21: Mechanical Properties I

MM 21.4: Talk

Tuesday, March 23, 2010, 11:00–11:15, H6

Complementary Climb Systems: Deformation Mechanism in Complex Metallic Alloys — •Michael Feuerbacher, Stefan Roitsch, and Marc Heggen — Institut fuer Festkoerperforschung, Forschungszentrum Juelich GmbH, 52345 Juelich

Complex metallic alloys (CMAs) are hallmarked by a high number of atoms per unit cell and a cluster based substructure dominated by icosahedral atom coordination. Due to their large lattice parameters, conventional dislocation-based deformation mechanisms are prone to failure in these materials. In recent years we have experimentally characterized the plastic deformation mechanism of a number of CMAs. We find that in many instances, strain is mediated by dislocations moving by pure climb. In uniaxial compression experiments we find two sets of dislocations. One set is moving on planes perpendicular to the compression direction by positive climb. This leads to shortening of the sample by removal of atom planes and consumes vacancies. The second set has habit planes perpendicular to the compression direction. This set moves by negative climb and hence acts as a vacancy source for the first system. The complementary action of the two sets avoids vacancy depletion and breakdown of the plastic deformation mechanism. The measured dislocation densities lead to vacancy diffusion distances consistent with the applied deformation rates in our experiments. We demonstrate the action of this mechanism in a number of CMA phases.