Processing of magnetic materials enhanced by magnetic or electric fields or currents
The proposal intends to improve the fundamental knowledge of processes in magnetic materials which are subjected to electric currents of high density, magnetic or electric fields of high strength, by going beyond empirical experience in exploiting the potential of electric and magnetic field-assisted material processing. This will give better predictions of magnitudes for the fields or currents needed to alter crystals and microstructures and of final properties of model systems through acceleration or retardation of phase formation reactions, stabilization of metastable phases, independent control of grain growth and texture as well as chemical order.
The main objective of this project is to give good answers to the following general question: How can external magnetic fields, electric fields or currents act on internal atomic defects, local structural or chemical disorder, phase formation, and microstructure in intermetallic phases in such controlled and efficient ways that specific functional properties of the material become significantly enhanced in a positive manner?
The essence of this proposal is the use of field/current-assisted processing to discover/develop advanced rare earth-free/lean high performance permanent magnets based on the understanding of the effect of fields. At the heart of the research plan is a symbiotic partnership between theoretical and experimental activities.
By using magnetic field assisted processing (T up to 1000 °C, H up to 14 T) or current assisted processing (current density up to 5000 A/mm2) we expect to develop several new magnetic materials. Experimental goals are 1) the searching for new ferromagnetic phases with high uniaxial anisotropy and magnetisation, and 2) the compositional and microstructural development for hard magnetic materials either made from these new phases, or by reducing the most critical elements in existing magnets. The obtained results will be validated on technologically and, equally important, economically relevant materials (Nd-Fe-B, Fe-Pt vs Fe-Ni and Mn-X).
Experiment will deliver data on well-defined model systems to link with the theoretical part of the project which aims to set up a DFT methodology to study field and current effects on elementary diffusion processes which contribute to compositional ordering of non-dilute binary ferromagnetic phases. In the first period of this priority programme the theoretical efforts will concentrate on crystalline systems with “only“ atomic defects and disorder. The extension from there to field or current effects on transport properties of atoms at extended planar defects in polycrystalline microstructures will be an ambitious perspective for the second period.
Prof. Dr. Oliver Gutfleisch
Apl. Prof. Dr. Christian Elsässer
Technical University Darmstadt
Institute for Material Science- FG Functional Materials
Freiburg Materials Research Center (FMF)
Tel: (+49) 6151 16 22150
Tel: (+49) 761 5142 286
Fax: (+49) 6151 16 22145
Proj.-Nr. GU 514/8-1
Proj.-Nr. EL 155/28-1