Mechanism of Ti-rich grain boundary phase formation and coercivity reinforcement in Sm(Fe0.8Co0.2)( 11)TiBx melt-spun ribbons

The effects of boron doping on the microstructure and magnetic properties of Sm(Fe0.8Co0.2)11TiBx melt-spun ribbons were investigated. At a quenching speed of 25 m/s, the Ti-rich grain boundary (GB) phase and more percent of SmFe12 phase was formed in the sample with x = 0.25, which increase the coercivity from 3 kOe to 6 kOe and remanence from 61 emu/g to 75 emu/g. The Ti-rich grain boundary phase show TiFe2-type structure, in which the (02-1) plane spacing of the grain boundary phase is half that of the adjacent (020) plane spacing of ThMn12 phase. Electron holographic analysis showed that the Ti-rich GB phase can reduce the magnetization coupling between the SmFe12 main phase grains. This served as a guide for the further fabrication of the GB phase in SmFe12-based permanent magnetic materials with high magnetic properties.