Dresden 2009 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 35: Poster Session II

MM 35.38: Poster

Mittwoch, 25. März 2009, 16:30–18:30, P4

Simulations of martensitic phase transitions in FeNi- and NiTi-alloys — •Daniel Mutter and Peter Nielaba — Physics Department, University of Konstanz, 78457 Konstanz, Germany

In order to find out possibilities of a realization of shape-memory systems on the nanometer scale, molecular-dynamics simulations were carried out for iron-nickel- and nickel-titanium-alloys with a maximum of about 5000 particles.
The used potentials arise from the embedded-atom method and can be found in the literature (FeNi [1], NiTi [2]).
The origin of shape-memory behavior are the martensitic and austenitic phase transitions between different crystal structures at certain temperatures or external stresses.
In our simulations, we investigated the temperature-driven phase transformations under the following conditions: free or periodic boundary conditions, surfaces of different structures, on which the simulated systems were placed, vacancies in the systems and various alloy compositions.
An evaluation of bond-orientational order-parameters [3] gives detailed information of the local structure during the phase changes.
[1] R. Meyer, P. Entel, Phys. Rev. B 57, 5140 (1998).

[2] W. S. Lai, B. X. Liu, J. Phys. Cond. Mat. 12, L53-L60 (2000).

[3] P. J. Steinhardt et al., Phys. Rev. B 28, 784 (1983).