Review of Rare Earth Nanocomposite Magnets

摘要

In this article, recent developments in rare earth nanocomposite magnets are reviewed. The emphasis is focused on the development of (Nd,Pr)_2Fe_14B(C)/alpha-Fe magnets with more homogeneous microstructure (especially finer Fe grains) and improved magnetic properties caused by the substitution of Nb for Fe, the use of rapid thermal annealing, and the direct quenching from the melt. In melt-spun Sm_2(Fe,M)_17Cx/alpha-Fe magnets a small amount of substitutions M (M=Ga, Al, si and Cr) is found to stabilize the 2:17 structure with a strong c-axis uniaxial anisotropy. Nanoscaled 2:17/alpha-Fe magnets with high coercivity and high M_r/M_s ratio has been developed in melt-spun Sm_2(Fe,Cr)_17Cx/alpha-Fe magnets. Our latest studies have led to the development of mechanically milled PrCo_5/Pr_2O_17 nanocomposite magnets with uniform nanoscale microstructure and outstanding magnetic properties which make them good candidates for high temperature aplications.