Micromagnetism and microstructure - tailoring of high-performance permanent magnets

The magnetic properties of hard magnetic materials are closely connected to their microstructure. The complexity of this correlation is demonstrated for the two most promising permanent magnet (pm) materials at present, namely nanocrystalline RE(2)Fe(14)B (RE = Nd,Pr) and nanostructured Sm(2)(Co, Cu, Fe, Zr)(17). In both cases the detailed analysis of the micro structure-property interaction by means of different high-resolution electron microscopy techniques, hysteresis loop measurements and the theory of micromagnetism results in a quantitative interpretation of the occurring hardening mechanisms, enabling a quite specific tailoring of optimized magnetic properties up to elevated temperatures.