Study On Constant Permeability Of Fe-Si-B Amorphous Alloys

In this dissertation, the constant inductance of two Fe-Si-B amorphous alloys had been investigated. The two Fe-based amorphous alloys Fe₇8Si₉B₁3 and Fe₈0Si₉B₁1 were prepared by a single-roll melt-spinning method. Some experimental means were employed, including X-ray diffraction, differential scanning calorimetery, static magnetism measurement and dynamic one and so on. Using these means, the effects of crystallization behaviour, cooling rate and pre-annealing technology on the magnetic properties of the two amorphous alloys with heating were determined. The results from the experiment were summed up as following:The inductance values of the two amorphous alloys monotonously decreased with the increase of crystallization volume , after annealed for proper time at proper temperature, the two alloys could attain the performance of constant permeability that ascribed to the stress parallel with the surface of the ribbon on the matrix caused by the contraction of the crystallized surface of the amorphous alloys , the magnetization vectors affected by magnetoelastic coupling in the matrix turned to the direction perpendicular to the surface of the ribbons, in the meantime, the material possessed of excellent DC bias characteristics. In addition, cooling rates had effect on the magnetic properties of the two annealed alloys ,and more for Fe₇8Si₉B₁3 than Fe₈0Si₉B₁1 alloy . Inductance attained in the slow cooling way was lower than that in the fast cooling way.The processes of the crystallization of the Fe₇8Si₉B₁3 and Fe₈0Si₉B₁1 amorphous alloys were basically same. That is amorphous - α -Fe(Si) + amorphous-Fe_xB_y+α -Fe(Si) +amorphous- α -Fe(Si)+ Fe2B, Metastable Fe3B then transformed into a stable phase of Fe2B and α -Fe(Si) at a higher annealing temperature. In addition, when the alloys were in the crystallization , lattice parameter of α -Fe(Si) gradually decreased with the increase of annealing temperature or time due to the replace of Fe atom by Si atom dissolving in α -Fe(Si) phase. However, There were more differences between the processes of the crystallization of the two amorphous alloys , one hand, the onset temperatures of the two amorphous alloys determined by the dynamic DSC curves at...