抄録
The precipitation process of highly resistive soft magnetic Fe-M-X (M=Al, B, Sm, V; X=O, N) films was investigated. The process can be understood in terms of a difference of Gibbs free energies between M-X and Fe-X, the atomic diffusion rate for M, X in α-Fe, and crystallization of the intergranular phase. Fe-(Al, Sm)-O films, which have large -ΔG°diff, exhibited a stable fine crystal structure in the as-sputtered state. By analyzing the precipitation process, using Johnson-Mehl-Avrami plotting, we found that the slow atomic diffusion in α-Fe brings about the lowest coercivity. Specifically, Fe-(Al, Sm)-O films, which have low diffusion rates, have exhibited Hc of 0.5-1.0 Oe, while Fe-V-O films, which have also low diffusion rates, showed a rapid and distinct crystal growth of the intergranular phase (V-O) at an early stage of the precipitation process. This allowed a rapid growth of α-Fe, which had been suppressed in the other Fe-M-X systems.
