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DY: Fachverband Dynamik und Statistische Physik

DY 29: Poster II

DY 29.45: Poster

Donnerstag, 28. Februar 2008, 16:00–18:00, Poster C

Segregation Dynamics and Local Order Parameters at Binary Alloy Surfaces — •Sebastian Kapfer¹, Harald Reichert², and Klaus Mecke¹ — ¹Institut für Theoretische Physik I, Erlangen, Germany — ²Max-Planck-Institut für Metallforschung, Stuttgart, Germany

Ordering phenomena in alloys are known to be heavily modified by the presence of surfaces. Recent X-ray scattering experiments reveal surprising effects in the ordering dynamics of Cu₃Au [Europhys. Lett. 53, 570 (2001)]. A T-CVM (tetrahedron cluster variation method) free energy expression is used which reproduces correctly the topology of the experimental phase diagram. The CVM is extended for systems with a surface to study in a kinetic model the effect of surface segregation on the dynamics of the ordering process following a rapid quench.

In a complementary effort, we study time-resolved transmission electron microscopy of Cu₃Au surfaces with atomic resolution. The monitored fluctuations of the local order parameter can be analyzed by morphological measures and compared with a Gaussian field theory in real space.