Phase equilibria at 1150 degrees C in the Co-rich alloys Sm-Co-Zr and structure of the 1:7 phase

In the concentration range 75-100 at.% Co, the isothermal section at 1150 degrees C of the system Sm-Co-Zr is determined experimentally. The following features are evidenced:a very small Sm solubility in Co, Zr2Co11, and Zr6Co23, an extended Zr for Sm substitution rate in SmCo3, Sm2Co7 and Sm5Co19, and a significant Zr solubility in SmCo5 and Sm2Co17 that induces the existence of a continuous ternary single phase 1:7. On the basis of the lattice parameter data, the formation of this phase by the substitution of Co dumbbells and/or Sm atoms for Zr atoms is proposed.