Elaboration and optimization of magnetic alloys: Sm-Co-Cu-Fe-Zr by study of phase diagrams

Technologically Sm-Co alloys are very important due to the good magnetic properties (high Curie's temperature, high spontaneous magnetization...) of the compounds. Real magnets are more complex than the binary intermetallics identified as potential hard-magnetic materials such Sm2Co17 and SmCo5. Another elements such as Zr, Cu and Fe are added to achieve special magnetic properties. All successful 2:17 magnets have a cellular microstructure within the grains. This cellular microstructure is obtained by annealing at low temperature of a homogeneous disordered phase called 1:7 (TbCu7 type structure). The aim of this study is to define the conditions of elaboration of 2:17 magnets and to optimize their magnetic properties from investigations of the phases equilibria in the quinary system Sm-Co-Fe-Cu-Zr. In a first step, the binary, ternary and quaternary systems: Sm-Co, Sm-Co-Cu, Sm-Co-Zr have been studied to understand the dependence of phase equilibria upon an addition of Cu,Zr. The obtained results have been presented in previous works. The present paper is relative of the study of the quaternary systems: Sm-Co-Cu-Zr and Sm-Co-Cu-Fe and some quinary samples in order to define the high temperature field of monophased 2:17 structure.