Research Group of Prof. Dr. M. Griebel
Institute for Numerical Simulation

Atomistic Simulation of Martensitic Phase Transformations


Marcel Arndt, Michael Griebel


We study structural phase transformations of crystalline solids by means of Molecular Dynamics (MD). In this approach, the specimen is modeled on the atomistic length scale by a system of interacting particles. The interaction is described by an interaction potential, which determines the specific material properties. The time evolution is then governed by Newton's second law. We use the different ensembles NVE, NVT and NPT to prescribe the total energy, the pressure and the temperature, respectively.

Martensitic phase transformations can already be simulated with the Lennard-Jones potential. For the realistic description of a material, more complicated potentials are necessary. We use the Embedded Atom Method (EAM), which provides such a potential. This potential reproduces the physical properties of metallic alloys to a large extent and thus allows us to simulate phase transformations in shape memory alloys.


As an exampe, we show the temperature driven phase transformation in a FeNi nanoparticle. The nanoparticle consists of Iron (80%, shown in green) and Nickel atoms (20%, shown in blue). It is heated from 100K to 800K. Here are snapshots at 100K, 480K and 530K.
The crosssections of the nanoparticle reveal the lattice structure. The following snapshots (again for 100K, 480K and 530K) show that the nanoparticle undergoes a phase transformation from the martensite bcc (body centered cubic) lattice to a mixed fcc (face centered cubic) and hcp (hexagonal close-packed) lattice in the austenite phase.
The whole transformation process is shown in the movie. In addition, the radial distribution density is plotted on the right side. Furthermore, the potential and the kinetic energy are plotted.


[1] M. Arndt, M. Griebel. Derivation of higher order gradient continuum models from atomistic models for crystalline solids. Multiscale Model. Sim. 4(2):531-562, 2005.
[2] M. Arndt. Upscaling from Atomistic Models to Higher Order Gradient Continuum Models for Crystalline Solids. Dissertation, Institute for Numerical Simulation, University of Bonn, 2004.

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