Mechanically alloyed nanocomposite magnets

Abstract
The magnetic and structural properties of mechanically alloyed Nd2Fe14B+ (Fe, FeCo) powders have been investigated over a wide range of temperatures. X‐ray diffraction patterns on samples milled for 48 h showed that the powders had a two‐phase structure consisting of a disordered Nd‐Fe‐B alloy and α‐Fe with a fine grain size about 140 Å. Enhanced magnetic remanence in the range of 95–105 emu/g with reduced remanence α=Mr/Ms=0.60–0.68 and a coercivity Hc=4–6 kOe have been obtained after annealing at 650–750 °C. This behavior is the result of an exchange coupling between the hard and soft phases with small grain sizes, about 500 and 200 Å, respectively.