A continuum model for heterogeneous nucleation - atomistic simulations on diffusive time scales
Titel (Englisch)
A continuum model for heterogeneous nucleation - atomistic simulations on diffusive time scales
Kurzbeschreibung (Deutsch)
Much progress in the understanding of pattern formation on mesoscopic scales is associatedrnwith the development of phase field (PF) models, which use a so-called phase fieldrnvariable to describe the thermodynamic state of a system, e.g. the solid and the liquidrnphase. However, a weakness of the traditional phase field (PF) methodology is that it isrnusually formulated in terms of fields that are spatially uniform in equilibrium. This elimiatesrnmany physical features that arise due to the periodic nature of crystalline phases,rnincluding elastic and plastic deformation, anisotropy and multiple orientations. Recentlyrna new extension to phase field modeling has emerged known as the phase field crystalrn(PFC) model. This model lives on an atomistic scale and describes the evolution of thernatomic density Z of a system according to dissipative dynamics driven by free energyrnminimization. In the PFC approach the free energy functional of a solid is minimizedrnwhen the density field is periodic. The periodic nature of the density field naturallyrngives rise to elastic effects, multiple crystal orientations and the nucleation and motionrnof dislocations. These physical effects are also included in other atomistic approaches,rnsuch as molecular dynamics (MD). A significant advantage of the PFC method is that, byrnconstruction, it is restricted to operate on diffusive time scales not on the prohibitivelyrnsmall time scales associated with atomic lattice vibrations. This will make simulations ofrnnucleation and growth feasible and thus will allow to relate nucleation and the formationrnof microstructures to each other.
Kurzbeschreibung (Englisch)
Much progress in the understanding of pattern formation on mesoscopic scales is associatedrnwith the development of phase field (PF) models, which use a so-called phase fieldrnvariable to describe the thermodynamic state of a system, e.g. the solid and the liquidrnphase. However, a weakness of the traditional phase field (PF) methodology is that it isrnusually formulated in terms of fields that are spatially uniform in equilibrium. This elimiatesrnmany physical features that arise due to the periodic nature of crystalline phases,rnincluding elastic and plastic deformation, anisotropy and multiple orientations. Recentlyrna new extension to phase field modeling has emerged known as the phase field crystalrn(PFC) model. This model lives on an atomistic scale and describes the evolution of thernatomic density Z of a system according to dissipative dynamics driven by free energyrnminimization. In the PFC approach the free energy functional of a solid is minimizedrnwhen the density field is periodic. The periodic nature of the density field naturallyrngives rise to elastic effects, multiple crystal orientations and the nucleation and motionrnof dislocations. These physical effects are also included in other atomistic approaches,rnsuch as molecular dynamics (MD). A significant advantage of the PFC method is that, byrnconstruction, it is restricted to operate on diffusive time scales not on the prohibitivelyrnsmall time scales associated with atomic lattice vibrations. This will make simulations ofrnnucleation and growth feasible and thus will allow to relate nucleation and the formationrnof microstructures to each other.
Zeitraum
08/2007 - 04/2016
Art der Finanzierung
Drittmittel
Projektleiter
- Herr Prof. Dr. rer. nat. habil. Axel Voigt
Projektmitarbeiter
- Herr Dipl.-Phys. Rainer Backofen
- Herr Prof. Dr. rer. nat. habil. Axel Voigt
Finanzierungseinrichtungen
Kooperationspartnerschaft
keine
Zugeordnete Profillinie
Materialwissenschaft, Biomaterialien, Nanotechnologie
Relevant für den Umweltschutz
Nein
Relevant für Multimedia
Nein
Relevant für den Technologietransfer
Nein
Schlagwörter
density functional theory, phase field modeling, nucleation