Towards a better understanding of intergranular phases in Fe-Nd-B sintered magnets

Abstract

Intergranular phases in Fe-Nd-B sintered magnets, which crystallize out of an under-sintering liquid phase, form a complex structure below 655 °C and influence the magnetic properties. In model experiments the microstructure has been coarsened to study the thermodynamics and kinetics of the intergranular regions in the as-sintered and as-annealed condition. It is found that after sintering eutectic solidification products are present in the grain boundaries which are transformed during annealing at moderate temperatures. Similar results are observed in as-cast Nd-rich model samples. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.