Studies of Rare-Earth - Transition Metal Permanent Magnet Materials

Studies of the anomaly in the magnetization of PrCo(,5) near 100K show the cause to be a switch from conical to axial anisotropy with rising temperature. The effects upon the magnetic properties rendered by the partial replacement of Pr in PrCo(,5) by La, Ce, and Nd were investigated. While Ce and La substitutions enhance the anisotropy, they diminish the magnetic moment and the Tc. Nd substitution caused an elevation in Tc and Ms but diminished the anisotropy. Effects of the introduction of small amounts of M = Ti, Zr, and Hf for Pr in Pr(,(1-x))M(,x)Co(,5) were studied; a drop in moment and anisotropy but a surprising elevation in Tc were observed. While Ti and to a lesser extent Hf could partially replace Co in Pr(,2)Co(,(17-x))M(,x), it was found the Zr can only enter the crystal structure by substituting for Pr, as in Pr(,(2-x))Zr(,x)Co(,17). In the Ti- and Hf-doped alloys, spin reorientation effects were observed, but they were not apparent in the Zr-doped alloys. In the Cu-containing alloys with the formula Pr(,2) (Co(,16)Cu)(,(17 -x)/17)M(,x), it was found that Ti, Hf, and Zr could be introduced up to x = 1.0. Substitution by Zr showed the greatest effects upon spin reorientation temperature and anisotropy. Fundamental magnetic properties of the R(,2)Fe(,14)B compounds with R = Y, Ce, Pr, Nd, Sm, Gd, Dy, Ho, Er, Yb and Th were studied. The rare earths nearly reach their free ion moments and the usual R-T coupling systematics are observed in this class of compounds. Permanent magnets based upon PrCo(,5) and upon Pr(,2)Fe(,14)B were fabricated. Respectable energy products were obtained (e.g. 26MGOe and 42MGOe for PrCo(,5) and Pr(,2)Fe(,14)B magnets respectively).