Effects Of Cu On The Glass-Forming Ability And Soft Magnetic Properties For Fe-Based Amorphous Alloy

Fe-based amorphous alloys possess excellent magnetic, mechanic and electrochemistry properties, have wide and promising application prospects in functional, structural, environmental protection material fields. The research of enhancing the glass-forming ability(GFA) of the bulk amorphous alloys, reveal the essence of the glass transition and improvement of the soft magnetic properties are important research issues topic for bulk amorphous alloys in material physics. In this thesis, effects of Cu element substitution for Fe or Nb on the GFA and soft magnetic properties also with the physical mechanism were investigated systematically in typical compound Fe72B20Si4Nb4. and also the physical mechanism. The main research includes and Innovations include:(1) It was found that proper Cu substitution for Fe triggers the transformation of the primary crystalline phase from single Fe23B6 to the coexistence of Fe23B6 and α-Fe phases.The formation of competitive Fe23B6, α-Fe and amorphous phases, which makes the crystallization behavior during crystalline process more difficult, therefore improves the GFA of the alloy.(2) The Cu substitution for Fe also improves the soft magnetic properties of the alloy. As Cu content increases, the saturation magnetization increases first, when x = 0.6, it increases to the maximum of 1.245T; as Cu content furtherly increases, the saturation magnetization decreases.The permeability of the alloys shows a trend that it increases first and then decreases as Cu content increases, while the covercivity decreases first and increases then. The main reason is considered that Fe atoms and Cu atoms in the amorphous alloys are mutually exclusive, and the minor Cu substitution for Fe enhances the atomic interaction between Fe – Fe in limited space, however, further Cu addition results in a sharp decrease in Fe content.(3) Proper Cu substitution for Nb improves the saturation magnetization without reducing GFA, hence lowers the cost. This is mainly due to the decrease of big Nb atoms by Cu substitution and less distance between Fe atoms, which enhances the exchange interaction between the Fe atoms, and improves the saturation magnetization.