Nanocrystalline SmCo12 main-phase alloys with V-doping: Structure stability and magnetic performance

Abstract

The intermetallic compounds based on the tetragonal ThMn12 prototype crystal structure have exhibited great potential as advanced rare-earth-lean permanent magnets due to their excellent intrinsic magnetic properties. However, the trade-off between the phase stability and the magnetic performance is often encountered in the ThMn12-type magnets. This work was focused on the effects of V doping and nanostructuring on the phase stability and magnetic properties of ThMn12-type Sm-Co-based magnets. Novel SmCo12-based nanocrystalline alloys with the SmCo12 main phase were prepared for the first time. The prepared alloys from the optimal design achieved obviously higher coercivity than the isotropic SmFe12-based alloys, together with comparable performance of other magnetic features. The enhancement in the coercivity was ascribed to the pinning of domain walls by the nanocrystalline grain boundaries and stacking faults. First-principles calculations and magnetic structure analysis disclosed that V substitution can stabilize the SmCo12 lattice and elevate its magnetocrystalline anisotropy. This study provides a new approach to developing stabilized metastable structured rare-earth-lean alloys with high magnetic performance.