Coercivity in ThMn12 -type magnets

Abstract

Fe-rich and RE-containing phases with the ThMn12 structure show interesting intrinsic magnetic properties. The single-phase composition Fe80Mo12Sm8 has a saturation magnetization of 10 kG, a Curie temperature of about 200 °C, and an anisotropy field of about 90 kOe, with the saturation magnetization and the Curie temperature being further improved by a Co substitution. In this contribution we report on the first experiments to create coercivity in these samples. As preparation techniques we applied mechanical alloying and rapid quenching which both result in microcrystalline material. The highest coercivity (3.8 kOe) so far was obtained for a multiphase sample prepared by mechanical alloying and a successive heat treatment at 800 °C. The dependence of coercivity on composition for these samples is discussed. Results for rapidly quenched material are also presented.