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magnetic materials

influence of composition and processing on phase composition and microstructure

Using TEM we are able to study the influence of the processing on the morphology and the grain size, the grain boundary composition and the phase boundaries on the final microstructure, and the influence of these factors on the magnetic properties.

Recently, we made a study of the influence of various additives like Zr on the induced anisotropy in Nd2Fe14B (Figure 1) and Ta on the development of microstructure in the RE2TM17N3-d powders processed by the HDDR technique (Figure 2).

Analytical microscopy is one of the few methods that allow us to make such studies and due to the complicated and demanding preparation of samples for the TEM and EDXS analyses from agglomerated nanocrystalline magnetic powders we needed to develop a special preparation method.

Figure 1: (left) TEM bright field image of partially disproportionated alloy (decomposition of NdFeB grain), (right) partially recombined NdFeB crystallite (around the NdH2 phase) during the HDDR processing of nanocrystalline NdFeB powders
(A: NdFeB, B:
a-Fe, C: NdH2)

Figure 2: A TEM picture of SmFeTa as cast material (left) and HDDR-ed material (right)


comments & suggestions to:  sanja fidler