Berlin 2015 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 24: Magnetic Materials I
MA 24.11: Vortrag
Mittwoch, 18. März 2015, 12:15–12:30, H 0112
Development of Microstructure in Mn-Al-C Permanent Magnetic Materials — •Florian Bittner1,2, Ludwig Schultz1,2, and Thomas George Woodcock1 — 1IFW Dresden, Institute for Metallic Materials, P.O. Box 270116, 01171 Dresden, Germany — 2Department of Materials Science, TU Dresden, Dresden, Germany
Mn-Al based materials have the potential for an application as rare earth free permanent magnets and could replace Nd-Fe-B in certain areas where the highest energy density is not required. The metastable τ phase in near equiatomic Mn-Al alloys is L10 structured and has high saturation magnetisation and magnetocrystalline anisotropy. Carbon atoms on interstitial sites increase the thermal stability of the τ phase, enabling processing at higher temperatures. In order to develop anisotropic magnetic properties, an easy axis texture must be induced by hot working. Coercivity strongly depends on microstructure and the presence of defects in the material is particularly important. In order to optimise the coercivity, it is therefore necessary to have detailed knowledge of the microstructural features which appear in these magnets, especially the type of defects, their formation mechanisms and the effect of processing on their fractions. Mn-Al-C magnets have therefore been studied in the as-cast, annealed and hot worked states using electron backscattered diffraction. Two different twinning systems were found to exist in the as-cast material, the fractions of which changed after hot working. These crystalline defects, other microstructural parameters and the magnetic properties will be discussed in terms of the various processing steps applied.