Enhanced Magnetic Properties and Thermal Stability of Nd2Fe14B/SmCo5 Composite Permanent Magnets Prepared by Spark Plasma Sintering

Nanocomposite Nd₂Fe₁₄B/SmCo₅ permanent magnets with different weight ratios have been prepared by spark plasma sintering mixtures of homemade amorphous SmCo₅ powders and commercially available Nd₂Fe₁₄B powders. The magnetic properties of the nanocomposite magnets are sensitive to the ratio of the two hard phases. The peak (BH)max value of 14.4 MGOe is obtained at the SmCo₅/Nd₂Fe₁₄B ratio of 4:1, which is ~50% higher than that of the single-phase SmCo₅ magnet prepared under the same preparation conditions. Hysteresis loop of the nanocomposite magnet shows the characteristics of single-phase magnet due to strong exchange coupling between the two phase grains. At high temperatures, the nanocomposite magnets exhibit greatly improved thermal stability compared with the single-phase Nd₂Fe₁₄B magnet.