Investigation of nanocomposite materials with ultrasoft and high performance hard magnetic properties

Abstract In the system of Fe73.5−xCoxNb3Cu1Si13.5B9 (x=0, 2, 4, 6, 8) with increasing Co content the size of nano-particles in heat-treated ribbons, the Curie temperatures of amorphous phase and crystalline phase, and volume fraction of the heat-treated ribbons of α-Fe(Si) phase increase while the crystallization activation energy of α-Fe(Si) phase decreases. The presence of Co substituted for Fe makes the crystalline phase to be formed easily. Ultrasoft magnetic properties are established in the samples. The as-cast Nd4.5Fe73.8B18.5Co2Nb1Cu0.2 ribbons are thermal-annealed in the range of 580–620°C for obtaining multiphase materials. After annealing at 610°C in 20 min, HC reaches 2.9 kOe, Br=11.9 kG, the reduced remanent ratio Mr/Ms=0.76 and maximum energy product (BH)max=15.2 MGOe.