Magnetic properties and microstructure of Sm-Co-Fe-Cu-Zr-Hf spark plasma sintered magnets

Abstract In this work, Sm24.6Co50Fe17·4Cu5·7Zr2.3-xHfx (x = 0–2.0) ribbons and magnets were prepared by melt-spinning method and spark plasma sintering (SPS) technique. The magnetic properties of the melt-spun ribbons with Hf addition are much higher than those of the Hf-free ribbons in the temperature range of 300–400 K. The optimal comprehensive magnetic properties of ribbons and isotropic magnets were obtained with 1.0 wt% Hf substitution. Microstructural results showed that Hf elements do not enter into the hard magnetic 1:7H and 2:17R phase in SPSed magnets and Zr–Hf rich phases are formed around grain boundaries as particulates. The enhancement of magnetic properties of the ribbons and SPSed magnets can be attributed to grain refinement and more uniform microstructure as a result of Hf addition. The micro-twin structure of 2:17R phase also have been discovered in the spark plasma sintered magnets. This work may provide a rapid preparation of Sm2Co17 magnets.