The ternary system Sm-Co-Zr isoplethic sections at Co=87 and 85 at%

The knowledge of solid-liquid equilibria is necessary to optimise sintering temperature in industrial Sm2Co17 type magnets. A single-phase state is reported as precursor of the cellular microstructure of the Sm2Co17 permanent magnets. The formation of this phase at high temperature seems, for a large part, to be governed by Zr addition. In order to understand the behaviour of 2/17 type magnets, phase relationships have been investigated in the Go-rich field of the Sm-Co-Zr system. An isoplethic section with 89 at% Co has been presented already in a previous study. In the present paper, we have investigated the 1150 degrees C isothermal section with lower Co content. Two isoplethic sections have been constructed for temperatures between 1150 degrees C and the melting points of the alloys with 87 and 85 at% Co. Two four-phase equilibria have been observed. In the Go-rich range of the ternary Sm-Co-Zr system, a tentative projection of the univariant liquidus lines has been constructed.