Atomistic simulations of martensitic transformations in 2D Lennard-Jones solids

Condensed Matter lunchtime seminar

Atomistic simulations of martensitic transformations in 2D Lennard-Jones solids

  • Event time: 1:00pm
  • Event date: 22nd January 2007
  • Speaker: Oliver Kastner (University of Edinburgh)
  • Location: Room 2511,

Event details

'Shape memory alloys' have the ability to recover significant deformations which are applied to a specimen at low temperature simply by change of temperature above a certain level. The underlaying physical mechanism of this famous effect are solid-solid phase transformations of the crystal lattice called martensitic transformations.

In the talk we present atomistic simulations of such lattice transitions by use of 2D Lennard-Jones solids. Two approaches are presented: First we consider a sequential arrangement (''chain'') of small, discrete 2D crystals interpreted as ideal lattice elements. Such chains are investigated in numerical tensile tests under displacement control at different temperature. The results show that this experimental setup allows for the simulation of the thermo-mechanical behavior of shape memory alloys, like pseudo-plasticity, pseudo-elasticity and the shape memory effect.

The second approach concerns many-body assemblies of up to 40,000 atoms in 2D. Allowing for free surfaces, it is possible to study the dynamics of lattice transitions evolving freely along the model dimensions. One aim of the work is the study of the thermo-mechanical conditions influencing the so called 'twinning process' and related domain formation known from the real material.

The project is still in progress; granted by the ''HPC-Europa''-program, the work gained a big push in both technical regards and physical understanding during the past 6-week visit in Edinburgh. The technical expertise of the EPCC staff, as well as the splendid working conditions at the local Department of Physics are sincerely appreciated!

This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..

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