Magnetism in iron alloys: thermodynamics, kinetics and defects
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
- “Accelerated grain boundary migration in nanolaminated interstitial-free steel during chromizing”, Materials Research Letters 9 (2020) 84-90
S.L. Xie, S.V. Divinski, Y.B. Lei, Z.B. Wang
(See online at https://doi.org/10.1080/21663831.2020.1827072) - “Atomic relaxation around defects in magnetically disordered materials computed by atomic spin constraints within an efficient Lagrange formalism”, Phys.Rev. B 102 (2020) 144101
O. Hegde, M. Grabowski, X. Zhang, O. Waseda, T. Hickel, C. Freysoldt, and J. Neugebauer
(See online at https://doi.org/10.1103/PhysRevB.102.144101) - “Study of grain boundary self-diffusion in iron with different atomistic models”, Acta Materialia 188 (2020) 560–569
S. Starikov, M. Mrovec, R. Drautz
(See online at https://doi.org/10.1016/j.actamat.2020.02.027) - Ab initio study of the structural response to magnetic disorder and van der Waals interactions in FeSe. Phys. Rev.B, 103 (2021) 054506
F. Lochner, I.M. Eremin, T. Hickel, and J. Neugebauer
(See online at https://doi.org/10.1103/PhysRevB.103.054506) - “Ab initio based models for temperature-dependent magnetochemical interplay in bcc Fe–Mn alloys”, Phys. Rev. B 103 (2021) 024421
A. Schneider, C.-C. Fu, O. Waseda, C. Barreteau, and T. Hickel
(See online at https://doi.org/10.1103/PhysRevB.103.024421) - “Angular-dependent interatomic potential for large-scale atomistic simulation of iron: Development and comprehensive comparison with existing interatomic models”, Phys. Rev. Mater. 5 (2021) 063607
S. Starikov, D. Smirnova, T. Pradhan, Y. Lysogorskiy, H. Chapman, M. Mrovec, R. Drautz
(See online at https://doi.org/10.1103/PhysRevMaterials.5.063607) - “Impact of magnetic transition on Mn diffusion in α-iron: Correlative state-of-the-art theoretical and experimental study”, Phys. Rev. B 104 (2021) 184107
O. Hegde, V. Kulitckii, A. Schneider, F. Soisson, T. Hickel, J. Neugebauer, G. Wilde, S. Divinski, C.-C. Fu
(See online at https://doi.org/10.1103/PhysRevB.104.184107) - “Influence of crystalline defects on magnetic nanodomains in a rare-earth-free magnetocrystalline anisotropic alloy”, Phys. Rev. Materials 5 (2021) 064403
D. Palanisamy, A. Kovács, O. Hegde, R. E. Dunin-Borkowski, D. Raabe, T. Hickel, and B. Gault
(See online at https://doi.org/10.1103/PhysRevMaterials.5.064403) - “Ab initio calculation of themagnetic Gibbs free energy of materials using magnetically constrained supercells”, Phys. Rev.B 105 (2022) 064425
E. Mendive-Tapia, J. Neugebauer, and T. Hickel
(See online at https://doi.org/10.1103/PhysRevB.105.064425)
