Structure and magnetic properties of Nd-Fe-B alloys with Cu additions, obtained by mechanical synthesis

In this work the phase transformations in Nd-Fe-B alloys with copper additives obtained by mechanochemical synthesis (MS) was studied. After MS process a partial decomposition of the Nd2Fe14B crystalline phase into the amorphous phase and α-Fe occurs with a maximum ratio of 20 and 8%, respectively. According to SEM data, the particle size was 1 μm with a substructure. The heat treatment of Nd-Fe-B alloys with Cu additives leads to crystallization of the amorphous phase and an increase in coercive force and residual magnetization. The maximum hysteresis properties were achieved for the sample with the addition of 0.4% Cu: Hc = 376 kA / m and σr = 65 A·m2/kg. It was shown that an increase in coercive force is associated with the presence of a mechanism for pinning of domain walls.