Properties of isolated single crystalline and textured polycrystalline nano/sub-micrometre Nd2Fe14B particles obtained from milling of HDDR powder

Textured, polycrystalline Nd2Fe14B powders, produced by dynamic hydrogenation disproportionation desorption and recombination (d-HDDR) were further processed by wet and surfactant-assisted ball milling. After 4 h of milling at 400 rpm in absolute ethanol and heptane + oleic acid, the polycrystalline d-HDDR particles had disintegrated, via intergranular fracture, into the individual grains i.e. isolated single crystalline particles of size 200 to 500 nm. An excellent degree of alignment was produced in the single crystalline particles using an applied magnetic field. This was reflected in the remanence of the field-aligned single crystalline powder (148.1 emu g(-1)) which was far higher than that of field-aligned un-milled d-HDDR powder (119.5 emu g(-1)). Milling the single crystalline powder further at 800 rpm in the same media produced polycrystalline flakes of size 0.2 to 1.0 mu m. The polycrystalline flakes showed (0 0 l) in-plane texture and thus oriented edge to edge in an applied field.