Project Details
Projekt Print View

Magnetism in iron alloys: thermodynamics, kinetics and defects

Subject Area Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
Term from 2016 to 2021
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 316673557
 
Final Report Year 2022

Final Report Abstract

In close collaboration with partners from France, the project aimed at including magnetism and its impact on chemical bond formation into atomistic models of Fe and Fe-base alloys and applications to the thermodynamics and kinetics of these materials. An important part of the project consisted in experiments that were carried out in close coordination with the modelling activities. Two main strategies were followed for including magnetism. The first strategy focused on lattice based models. By constraining atoms to lattice positions, it is possible to describe their interactions very accurately from density functional theory. On the other hand, lattice based models enable the exhaustive sampling of magnetic degrees of freedom and in this way thermodynamic and kinetic properties were obtained. The second strategy aimed at situations where an underlying lattice cannot be easily defined. There it is necessary to coarse-grain and simplify the atomic interactions as direct simulations with density functional theory would be prohibitively expensive. To this end simplified models of the electronic structure (tight-binding approximation) and effective interatomic potentials (bond-order potentials, embedded atom method potentials) that include contributions from magnetism were developed. The two strategies were developed and demonstrated in a number of publications. The methods were directly applied to experimental problems and allowed particularly close state-of-the-art quantification of the experimentally observed diffusion and thermodynamic characteristics of pure Fe and Fe–Mn alloys. The impact of magnetic transition on self- (Fe) and solute (Mn) diffusion in α-Fe was understood in detail and examined with respect to all relevant contributions, including vacancy formation and migration energy, solute-vacancy binding and correlation effects.

Publications

 
 

Additional Information

Textvergrößerung und Kontrastanpassung