LAUSR

Abstract The effects of Ge substitution and synthesis via rapid solidification on the structure and magnetic character of the intermetallic Fe 5 SiB 2 (5-1-2) system were determined, with the objective to investigate the potential of Fe 5 (Si 0 . 75 Ge 0.25 )B 2 as a new permanent magnet material. Samples were made by arc-melting/annealing as well as by melt-spinning/annealing and were evaluated by probing the structure, composition, and magnetic response. Results indicate that the tetragonal Cr 5 B 3 crystal structure, large saturation magnetization (Ms = 153.8 emu/g) and Curie temperature (Tc = 784 K) of the parent Fe 5 SiB 2 phase may be preserved by substituting up to 25 at % of Si in the lattice with Ge. The room-temperature magnetocrystalline anisotropy constant of a Ge-substituted alloy of nominal composition Fe 5 (Si 0 . 75 Ge 0.25 )B 2 was evaluated as K 1  = 5 × 10 6  ergs/cc using the law of approach to saturation and is the largest reported to date within the 5-1-2 materials system. As a result of compositional modification, the spin reorientation observed in Fe 5 SiB 2 is greatly suppressed from 172 K to 60 K. A comparison of the 5-1-2 phase evolution when synthesized by standard casting and by rapid solidification indicates that melt spinning is a simpler and more expeditious synthesis method relative to previously reported solid-state reaction methods.