Effects of annealing temperature on microstructure and magnetic properties of Fe 73·37 Cu 0·92 Nb 2·9 Si 13·56 B 9·24 amorphous alloy

Fe_73·37Cu_0·92Nb_2·9Si_13·56B_9·24 amorphous alloy ribbon was prepared by melt spinning method. The influences of the annealing temperature on its microstructure and soft magnetic properties were investigated. Two crystallisation stages were found with temperature increasing by using differential scanning calorimetry. X-ray diffraction test showed that the first crystallisation phase is α-Fe(Si) with the average grain sizes ranging from 12 to 25 nm when annealing temperature is below 560°C and the secondary crystallisation phase with an average grain size of about 45 nm appears when annealing temperature is at 700°C. The soft magnetic property measurement showed that the B_s increases to 1·26 T and the H_c decreases to 0·002 Oe when annealing temperature increased from 520 to 560°C, while corresponding values for the alloy annealed at 700°C are 1·1 T and 0·079 Oe respectively. These results indicate that the Fe_73·37Cu_0·92Nb_2·9Si_13·56B_9·24 alloy annealed at 560°C has the relatively best magnetic properties.