Reducing Dy Content by Y Substitution in Nanocomposite NdFeB Alloys With Enhanced Magnetic Properties and Thermal Stability

Dy has been employed as an additive in NdFeB magnets to improve their coercivity and thermal stability, but the high cost of the Dy has become a major concern. In this work, the effects of Y substitution for Dy on the magnetic properties and thermal stability of melt-spun nanocomposite [Nd_0.8(Dy_1-xY_x)_0.2]₁₀Fe₈₄B₆ alloys have been systematically studied. The results show that Y substituting Dy can not only improve the remanence and energy product but also improve their thermal stability. [Nd_0.8(Dy_0.5Y_0.5)_0.2]₁₀Fe₈₄B₆ alloy with 50% Dy reduction exhibits a high maximum energy product of 139 kJ/m³ and low absolute values of temperature coefficients α and β, -0.090%/^°C and -0.394%/^°C, respectively. It is suggested that Y substitution be a feasible way to reduce the cost of the NdFeB magnets and maintain their high temperature performance.