The effect of Joule heating on the magnetic properties and microstructure was investigated in Fe73Al5Ga2P 11-xC5B4Six (x=1, 3) ribbons with a thickness of about 40μm. It turns out that, in these alloys, the coercive field, the pinning field and the time dependence of the initial permeability decrease with increasing current density applied during a thermal treatment via Joule heating up to the occurrence of crystallization. At the as-cast state, the sample with x=3 exhibits better soft magnetic properties than those of the sample with x=1; however, after an optimum annealing, both alloys present similar magnetic properties. The temperature dependence of the resistivity shows clear two stages crystallization process for the Fe73Al 5Ga2P8C5B4Si3 alloy. The microstructural and magnetic inhomogeneities of the annealed Fe 73Al5Ga2P8C5B 4Si3 alloy with lowest coercivity were investigated by means of a small-angle neutron scattering method. The improvement of the soft magnetic properties caused by Joule heating of materials is due to the internal stress relieve originated during the production of the ribbon and to the enlargement of the domain wall thickness, consequently the reduction of the anisotropy.
- Amorphous soft magnetic materials
- Coercive field
- Joule heating
- Pinning field
- Small-angle neutron scattering