Certain R2Co17 and R2 T14 B systems (R = a rare earth, T = Fe or Co) are of significance for use in the fabrication of high energy magnets. Improvements in these systems as high energy magnet materials are effected by partially replacing Co or T by appropriate d transition metals. A description is given of the magnetic behavior of a number of systems based on R2 Co17 and R2T14 B. Also, an account is given of recent work dealing with the systems RCo4 B and PrCo4-xFex B. The latter materials have large magnetizations and high Curie temperatures. However, they are not useful permanent magnet materials because they exhibit planar anisotropy.
Results of some Auger spectroscopy studies of R2 Fe14 B systems (R = Pr,Nd or Er) are presented. This work shows the intergranular region to be rich in B, O and R. This region is undoubtedly non-magnetic, a feature which is most probably of significance in regard to the observed coercivity of R2 Fe14 B magnets.