Strategies for efficient utilization of heavy rare-earth Tb in high-performance Ce magnets with high Ce content

Abstract

Permanent magnetic material Ce magnets are a sufficiently attractive energy material due to its cost-effective and environmental friendliness. Grain boundary diffusion processing of Ce magnets with high Ce content presents a challenge: a limited diffusion depth of heavy rare earths. We proposed a strategy for efficient utilization of heavy rare earth Tb in Ce magnets with high Ce content. Consequently, a rather encouraging coercivity of 16.37 kOe and a maximum energy product of 38.77 MGOe are reached by Tb diffusion in Ce magnets where Ce accounts for 40% of total rare earths. Diffusion source alloys containing Pr are designed using first-principles calculations. The Pr synergistic diffusion on the diffusion detail of elemental Tb is analyzed. The ability of Tb to enter the main phase is reduced due to the addition of Pr combined with the significant diffusion coefficient of Pr, which contributes to the enhancement of coercivity and thermal stability for diffused Ce magnet. Ce magnets remain cost-effective after diffusion of heavy rare earth Tb, which will shed light on the broadened application for Ce magnets in wind power generation, industrial motors, and medical robots.

Keywords

• Ce magnet
• Grain boundary diffusion process
• Efficient utilization
• Thermal stability
• Magnetic properties