Thermal Magnetic Behavior of Nanocrystalline Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 Ribbons

摘要

Thermal magnetic behavior and microstructure of Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9 ribbon annealed at different temperatures were investigated. It was indicated that the onset crystallization temperature of the ribbon was around at 530°C and its Curie temperature can be enhanced from 320°C to 385°C by annealing. X-ray diffraction structural analysis showed that a single a-FeSi crystalline phase with grain size about 12 nm was precipitated from amorphous matrix for FeCuNbSiB ribbons annealed between 530°C and 580°C. The α-FeSi phases were octahedral shape confirmed by the morphology simulation and the AFM method. The thermal magnetic behaviors were complicated, as the μ_i can be divided into two modes during increasing temperature, but for the Bs and Ms shown a normal decrease with increasing temperature. The coercive force Hc and remanence ratio α have shown a continuous monotonic decline in single-phase ribbon with increasing temperature, and increased to a max value or a peak and then decreased to zero in biphase ribbons. The thermal behaviors of magnetic properties were controlled by the exchange coupling interaction between the α-FeSi grains and the intergranular amorphous phase. It is important to maintain an efficient exchange coupling interaction between α-FeSi grains and the residual amorphous matrix, and it is necessary to sustain the higher Curie temperature for the application of the FeCuNbSiB ribbons in high temperature by controlling the size and crystallization degree of α-FeSi grains.