Effect of refractory metals addition on the structural and magnetic properties of Pr3(Fe, Co, Ti)29 system

Polycrystalline refractory metal-substituted Pr3(Fe0.6M0.1Co0.3)27.5Ti1.5 (M=V, Ti, Zr, Mo, Nb,Cr) and Pr3(Fe0.5Co0.5)27.5Ti1.5 have been studied for high-temperature permanent magnetic materials. X-ray diffraction showed the main phase to be the 3:29 phase. We observed the highest reported TC (Curie temperature) of 640 °C for the 3:29 system in the Pr3(Fe0.5Co0.5)27.5Ti1.5. In the refractory metal-substituted systems, the highest TC of 480 °C was observed for the Nb-substituted alloy. SEM measurements showed that Ti in Pr3(Fe0.6Ti0.1Co0.3)27.5Ti1.5 is deposited near the grain boundary. HA (anisotropy energy) of V-substituted alloy is as high as 72 kOe, the highest reported in the 3:29 system and is ∼200% higher than 24 kOe observed in Pr3(Fe0.7Co0.3)27.5Ti1.5. Cr and Ti substitutions show an increase of 65% (40 kOe) and 45% (35 kOe) in HA respectively. MS (saturation magnetization) values were ∼100 emu/g and are lower than that observed in Pr3(Fe0.7Co0.3)27.5Ti1.5.