First-principles study of structural stability and intrinsic magnetic properties of SmFe11Ti-type alloys with Ni addition

Although Ti is used to stabilize the ThMn12-ordered SmFe11Ti structure, it greatly degrades permanent magnetic performance; thus minimizing Ti in SmFe11Ti phase is imperative. Herein, using all-electron density functional theory calculations, we investigate the impact of Ni substitute atoms on the structural stability and intrinsic magnetic properties of the Ti-low-content SmFe11.5Ti0.5 phase. Our calculations show that the presence of Ni not only improves the formation enthalpy of SmFe11.5Ti0.5 structure but also enhances intrinsic permanent magnetic properties. Specifically, the SmFe11Ni0.5Ti0.5 phase is predicted to exhibit a saturation magnetization μ0Ms of 1.45 T and a uniaxial magnetic anisotropy Ku of 11.53 MJ/m3, leading to the higher theoretical maximum energy density product (BH)max, anisotropy field μ0Ha, and hardness parameter κ compared to the corresponding values of SmFe11Ti phase. These computational results suggest that the Sm(Fe,Ni,Ti)12 based alloys with optimal Ti and Ni content are potential candidates for high-performance permanent magnets.