[en] Crystallization behaviors of Fe₄₀Ni₃₈Mo₄B₁₈, Fe₃₈Ni₃₅Mo₄Si₅B₁₈, and Fe₃₉Ni₃₆Mo₂Si₅B₁₈ (at%) amorphous alloys as well as magnetic properties of the Fe₄₀Ni₃₈Mo₄B₁₈ alloy, annealed in the temperature range from 400 to 520 deg. C for 1 h, have been investigated. The results show that for the samples of Fe₄₀Ni₃₈Mo₄B₁₈, annealed in the temperature range of 430-450 deg. C, a single-crystalline FCC phase with composition near Ni₃Fe solid solution and grain size of about 10 nm precipitates in the amorphous matrix, and the samples exhibit good soft magnetic properties. As the samples are annealed at T _a≥470 deg. C, the magnetic properties drop rapidly, this is mainly due to the formation of Fe-B and Ni-B compounds. For the samples of Fe₃₈Ni₃₅Mo₄Si₅B₁₈ and Fe₃₉Ni₃₆Mo₂Si₅B₁₈, a single FCC crystalline phase structure cannot be formed in the amorphous matrix, where more than single-crystalline phase such as Fe-B compounds as well as γ-(Fe, Ni) phase are precipitated almost simultaneously by the annealing treatment