Intermediate phases in the hydrogen disproportionated state of NdFeB-type powders

Transmission electron microscopy studies have been carried out on partially disproportionated NdFeB-type alloys. A new intermediate magnetic (NIM) phase has been identified. Moreover, the lamella structure which subsequently develops from the tetragonal NIM phase comprises a tetragonal NdFe- containing (IL) phase and alpha -Fe. The experimental data show strong evidence of a well-defined crystallographic relation between both the NIM and lamella phases and between the IL phase and alpha -Fe. These observations give insight into how crystallographic texture, and hence anisotropy, can be developed in NdFeB-type powders processed by the hydrogenation, disproportionation, desorption, and recombination route