Effect of gallium and refractory metal substitution in 3:29 intermetallic permanent magnetic materials.

摘要

The search for high temperature permanent magnetic materials in recent years has led to the study of the 3:29 rare-earth transition metal intermetallic compounds. These materials have shown great promise due to their high magnetization, Curie temperature and anisotropy. They have been limited in their coercivity. The ability to tailor the microstructure of these materials particularly in the nanoscale will help harness the coercivity and have far reaching applications. In addition, their Curie temperature and magnetic anisotropy can be improved by optimizing the alloy compositions.; In this thesis, we present the effect of the substitution of Co, Ga and refractory metals in Pr3Fe27.5Ti1.5 on the magnetic properties. Co was substituted to improve the Curie temperature. Ga has no magnetic but helped to serve as a grain refiner which in turn increased the anisotropy. Amorphous and nanocrystalline grains formed by melt-spinning the Ga alloys. Co and refractory metal substitutions improved the Curie temperature and anisotropy significantly. From crystal field calculations, the easy magnetization directions have been predicted for different 3:29 rare-earth substitution compounds.