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MM: Fachverband Metall- und Materialphysik

MM 40: Topical session: In-situ Microscopy with Electrons, X-Rays and Scanning Probes in Materials Science IV - Atomic structure and defects III

MM 40.2: Vortrag

Mittwoch, 9. März 2016, 16:15–16:30, H38

In-situ TEM isothermal annealing of nano-crystalline supersaturated Cu-Cr thin film alloys — •Tristan Harzer, Jazmin Duarte, and Gerhard Dehm — Max-Planck-Institut für Eisenforschung GmbH, Structure and Nano-/Micromechanics of Materials, Max-Planck-Strasse 1, 40237 Düsseldorf, Germany

The thermal stability and decomposition behavior of nano-crystalline single-phase Cu-Cr thin film alloys grown far from equilibrium were investigated by isothermal heat treatments. In the as-deposited state, the alloy films exhibit supersaturated solid solutions with a fcc and bcc structure for alloy compositions containing 4 at.% and 33 at.% Cr, respectively. Isothermal annealing in a temperature range of 150 °C - 500 °C were conducted inside a TEM and compared to phase stability data obtained by XRD under comparable annealing conditions. It is shown that the single phase nature of the alloy films is maintained for annealing temperatures of up to 300 °C, whereas heat treatment at temperatures of 400 °C or higher results in the formation of the two phase equilibrium film structures. Film decomposition in case of the Cu-4 at.% Cr thin film alloy proceeds via enrichment of Cr at grain boundaries and grain boundary diffusion whereas phase separation of the Cu-33 at.% Cr thin film alloy progresses predominantly via volume diffusion. Temperature dependent diffusion coefficients for volume and grain boundary diffusion along with the respective activation energies are determined from analytical in-situ TEM. In addition, the influence of electron beam irradiation on the diffusion kinetics is considered.