Hard Magnetic Properties and Thermal Stability for TbCu7-Type SmCo6.4Si0.3Zr0.3 Alloys With Sm Substituted by Various Rare-Earth Elements

The magnetic properties and thermal stability of melt spun SmCo_6.4Si_0.3Zr_0.3 ribbons with various rare-earth (RE) elements substituted for Sm have been investigated. It is verified that the properties´ combination of SmCo₇-based ribbons can be modified by selected RE substitution. The light RE Ce is beneficial for enhancing the saturation magnetization and the remanence, while the coercivity and thermal stability can be significantly improved by heavy REs Gd, Ho, and Er substitutions. The highest room-temperature coercivity of 1467 kA/m was achieved in the Sm_0.7Gd_0.3Co_6.4Si_0.3Zr_0.3 ribbon. For the temperature range of 27 °C-200 °C, Gd is the best element for enhancing the thermal stability, and the optimal temperature coefficients α and β are -0.032%/°C and -0.269%/°C, respectively. For the range of 27 °C-400 °C, Ho is the best element to improve the thermal stability, and the values of α and β are -0.064%/°C and -0.19%/°C, respectively.