Preparation of highly coercive Sm-Fe-Ti by rapid quenching

Abstract

The magnetic properties of the hard magnetic 20:70:10 (ω) phase in melt-spun Sm20Fe70+xTi10−x (x=−2,0,2) and Sm25Fe65.6Ti9.4 were investigated. The intrinsic coercivity iHc and the magnetization J were measured as a function of both the melt spinning parameters and various heat treatments. The maximum coercivities iHc at room temperature for the compositions Sm20Fe70Ti10 and Sm25Fe65.6Ti9.4 are 44.5 and 58 kOe, respectively. These values are among the highest reported so far for melt-spun materials. The formation of Sm(Fe,Ti)12 nuclei during rapid solidification is revealed by x-ray diffraction, and its influence on the formation of the ω phase is discussed. By investigating the section Smx(Fe0.875Ti0.125)100−x of the ternary phase diagram, using differential thermal analysis and x-ray diffraction, we proved the ω phase to be metastable.