Based on a study of the phase relation in the Fe- and Co-rich region of the
equi-gadolinium content section with the Gd content corresponding to the c
hemical formula Gd-3 Fe, Co, Cr) (29) in the Gd-Fe-Co-Cr quaternary system,
formation, structure and magnetic properties of the 3 : 29-type Gd-3 (Fe1-
xCox)(29-y)Cr-y compounds have been investigated. It has been found that th
e composition range of formation of the single phase Gd-3 (Fe1-xCox)(29-y)C
r-y Compounds is 0 less than or equal tox less than or equal to0.7 for y =
5.0, 0.7 less than or equal tox less than or equal to 0.8 for y = 5.5, and
0.8 less than or equal to x less than or equal to 1.0 for y = 6.0. A pure C
o-based Gd3Co29-xCrx compound series have been synthesized. The solubility
limit of the Cr atoms in the Gd3Co29-xCrx compounds was found to be from x
= 6.5 to x = 7.3. The results indicate that all the synthesized Gd-3 (Fe1-x
Cox)(29-y)Cr-y compounds crystallize in Nd-3 (Fe, Ti)(29)-type structure of
the monoclinic system and the space group A2/m. The solubility limit of Co
atoms in the Gd-3 (Fe1-xCox)(29-y)Cr-y compounds increases with increasing
the stabilizing element Cr. It is noteworthy that substitution of Co for F
e leads to a remarkable change of the magnetocrystalline anisotropy of the
Gd-3 (Fe1-xCox)(29-y)Cr-y compounds. When x greater than or equal to0.4 the
anisotropy changes from the easy plane type to the uni-, axial type, which
is important for permanent magnet application.