Hard-magnetic melt-spun R–Fe–B alloys on the base of light rare-earth metals (R=La, Nd)

Abstract

Effects of La addition on microstructure and magnetic properties of LaxNd₃₃₋xFe₆₅.₉B₁.₁ (wt. %) melt-spun ribbons and isotropic bonded magnets were systematically studied. X-ray diffraction and DSC data revealed that addition of La led to the formation of highly refined and inhomogeneous La-rich phase. It was shown that the average grain size and volume fraction of the main magnetic (La,Nd)₂Fe₁₄B phase depend on La concentration. For better LaxNd₃₃₋xFe₆₅.₉B₁.₁x = 2.5 and 5 wt. % bonded samples, the room-temperature magnetic properties of Hci = 1343 kA/m and 1300 kA/m, and Br= 0.61 T and 0.614 T were obtained. Magnetic flux aging loss for alloys with appropriate La content (x = 5–10 wt. %) did not exceed 5 % in the range of 100–125°C, which is typical for conventional ternary Nd–Fe–B melt-spun magnets.