Berlin 2008 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 13: Growth

MM 13.6: Talk

Monday, February 25, 2008, 16:00–16:15, H 0111

Influence of Strain on Kinetics of Nonisothermal Solid-Solid Phase transitions — •Michael Fleck, Efim Brener, Robert Spatschek, and Guillaume Boussinot — Institut für Festkörperforschung, Forschungszentrum 52425 Jülich

Structural phase transitions in solids involve a discontinuous change in the lattice structure, leading to the presence of elastic deformations. In some cases, these effects are of minor influence and can be ignored, but nevertheless for many applications the elastic strain causes qualitatively new and observable effects.

A motion of the interface due to first order phase transitions is a source of latent heat due to the finite entropy difference of the two phases. This heat has to be transported away from the interface before further phase transformations can take place. From solidification or melting processes it is known, that these kinds of thermal effects can cause interface instabilities leading to dendritic growth, which is very important for many metallurgical applications.

We derive a thermodynamically consistent phase field model for nonisothermal solid-solid phase transitions, to be able to investigate the coupled influence of elastic and thermal effects on the kinetics of solid-solid phase transitions. We show results from simulations with different geometries and boundary conditions. In particular, we investigate the steady state growth in a narrow channel, and compare the results to analytical predictions for the region far behind the tip.