Team

Magnetic hardening by severe plastic deformation processes

Within the framework of project A08 of the collaborative research center CRC/TRR 270 “HoMMage – Hysteresis design of magnetic materials for efficient energy conversion”, the microstructure of different hard magnetic materials will be optimized to maximize their magnetic hysteresis. For that, powder samples are compacted and severely plastically deformed by high pressure torsion (HPT).

The use of powder blends of a ferromagnetic phase, such as SmCo5, Sm2Fe17N3 or Fe2P, together with a binder phase enables the production of hard magnetic nanocomposites. In contrast to conventional sintering, the choice of these phases is not thermodynamically limited. Depending on the binder properties, different magnetic interactions or decoupling of the magnetic particles are possible. The large plastic strains during the HPT deformation result in an increased defect density in the crystal structure as well as in a grain refinement, so that the coercivity is enhanced.

In this project, the influence of different processing parameters and compositions on the microstructure and magnetic properties of HPT samples is investigated. Besides, the magnetic properties are further improved by diffusion and recrystallization processes via heat treatments.