Effect of static magnetic field on microstructure and interdiffusion behavior of Fe/Fe–Si alloy diffusion couple

• Growth of intermediate phase in parabolic law is suppressed under magnetic field.
• Suppressed interdiffusion behavior is mainly due to the reduced frequency factor.
• Magnetic field direction hardly influences the diffusivity of intermediate phase.
• Movement of FeSi/Fe2Si and Fe2Si/Fe3Si interfaces is suppressed under magnetic field.

Effect of static magnetic field on microstructure and interdiffusion behavior in Fe–Fe50 wt.%Si diffusion couples has been investigated. The Fe2Si and Fe3Si layers could be hardly observed after annealing at 1050–1150 °C for more than 3 h without the 0.8 T magnetic field, however, the Fe2Si rather than Fe3Si layer could be still observed after prolonged annealing time up to 6 h with the magnetic field. The interface with higher Si content moved faster than that with lower Si content, which led to the reduced thickness of Fe2Si and Fe3Si layers, and finally both of them were replaced by the stable FeSi phase. The magnetic field exhibits a suppressing effect on the interdiffusion behavior of Fe/Fe–Si alloy because of the decreased thickness of FeSi and solid solution layers, and no significant difference between the diffusivities parallel and perpendicular to the magnetic field direction has been detected. The growth of FeSi and solid solution layers obeys the parabolic law and is suppressed under magnetic field due to the reduced frequency factor D0 but not the activation energy Q.

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