Regensburg 2010 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 28: Nanostructured Materials I

MM 28.5: Vortrag

Mittwoch, 24. März 2010, 11:15–11:30, H16

Thermal stability and reaction of nanocrystalline Fe/Cr multylayers — •Patrick Stender and Guido Schmitz — Institut für Materialphysik, Münster

Thermal stability and reaction of iron/chromium multilayers are analyzed using 3D atom probe technique. For this purpose, stacks of up to 50 layers of pure iron and pure chromium with a single layer thickness of 12 nm were deposited on blunted tungsten tips by ion beam sputtering. Subsequent isothermal and isochronal annealing sequences were carried out in an UHV furnace to investigate the thermal behaviour of the system. In a last processing step, samples were sharpened to 50 nm radius of curvature by annular milling using the focused ion beam technique. Although a miscibility gap exists between a chromium rich phase and an iron rich phase up to 820 °C, nevertheless a short-ranged mixing at the layer interfaces on the length scale below 2 nanometers is observed, which is interpreted by the Cahn Hilliard thermodynamics of inhomogeneous systems. Most remarkable, in suitable temperature-time windows above 550 °C, atomic transport across the metallic layers appears along 1D pipe geometries. This observation is interpreted by triple line transport in the nanocrystalline microstructure. Segregation and transport properties of the triple lines are determined.