Effect of Dy additive on microstructure and magnetic propertiesof rapidly solidified Nd-Fe-B strips

Sintered Nd-Fe-B magnets made from strip cast alloys have been studied extensively owing to their strong permanent magnetic properties. Up to now the studies mainly focus on technology parameters of strip casting, including casting temperature, wheel speed and phase transition temperature and so on. However, microstructure and properties of rapidly solidified strips could be influenced by the composition of alloy. In this work, the effects of added Dy element on microstructures and properties of Nd-Fe-B rapidly solidified strips have been investigated. The strips shad a pronounced texture of the tetragonal T1(2 ∶14 ∶1) phase as shown by the prominent (00l) peaks at wheel surface. The alignment coefficient of the strips was the highest when Dy content ranged from 1 to 2at%. This is the result of the microstructure of strips being optimized through an appropriate amount of Dy addition. At the same time, the volume fraction of isotropic crystal decreased as Dy content increased. It revealed that the oxidation speed decreased with increasing Dy content.