Powder consolidation of Nd-Fe-B/α-Fe nanocomposite materials by cold deformation process

Abstract

High-pressure torsion (HPT) was applied to Nd-Fe-B/α-Fe nanocomposite materials for the following two purposes. The first is to obtain anisotropic nanocomposite magnets by development of deformation texture, and the second is to consolidate bulk magnets directly from powder compacts without sintering process. Although no texturing occurred in this set of experiments, the consolidation was successful and increased the relative density up to 90% of a nanocomposite magnet having the coercivity Hc = 4.4 kOe and the remanence/saturation magnetization σr/σsat =100/165 emu/g. The shear strain gradient generated in a disc after HPT allowed us to discuss a relationship between shear strain and porosity, as well as the significance of shear in densification process.