Studies of crystallization and soft magnetic properties of FeNiMoB(Si) alloys

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 °C for 1 h, have been investigated. The results show that for the samples of Fe40Ni38Mo4B18, annealed in the temperature range of 430–450 °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 Ta⩾470 °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.