Evolution of phase and microstructure in anisotropic nanocrystalline SmCo_6.1Si_0.9magnets

The evolution of phase and microstructure has been investigated for the spark plasma sintered anisotropic nanocrystalline SmCo_6.1Si_0.9magnets. With the increasing of sintering temperature from room temperature to 680°C, the phase evolves from 1:7H (TbCu₇-type) single phase to 1:7H dominant phase plus 2:17 R (Th₂Zn₁₇-type) minor phase, and then to 2:17 R dominant phase with phase-transformation twins structure plus minor 1:5 H (CaCu₅-type) precipitated phase with particulate morphology. The evolution of phase and microstructure in anisotropic nanocrystalline SmCo_6.1Si_0.9alloys, as well as its effect on the coercivity is discussed and compared with that in nanostructured 2:17 type SmCo alloys.