Magneto-mechanical Effect on the Magnetic Properties and Microstructures in Nanocrystalline Fe-Cu-Nb-Si-B Alloys

In the current study magnetic, magneto-optical, and morphologic and structural properties of the amorphous Fe₈₂Cu₁Nb_3.5Si_5.5B₈ (NC1) and Fe_77.5Cu_1.5Nb₅Si₇B₉ (NC2) alloys were investigated at elevated temperatures with and without tensile loading. Kinetic nanocrystallization temperatures of certain ribbons were properly determined at the range of 500 °C to 555 °C. Furthermore, an unusual method was preferred to identify the tensile loading conditions regarding relative permeability values in the as-cast (AC) state to specify stress annealing conditions. The present properties yielded an ultrafine-grain structure correlated with the literature results. AC-state, tensile-loaded, heat-treated, and stress-annealed specimens were separately examined to ensure their improvement in terms of magnetic properties and structures as well as magnetic domains. Besides, variations of induced anisotropy with respect to tensile loading and coercivity made the evaluation of the magnetic microstructures possible. In addition, the observed magnetic domains contribute further knowledge to the available magnetic microstructures. Good correlation between the determined magnetic properties and observed microstructures was found. Eventually, the optimum nanocrystallization requirements of NC1 and NC2 could be determined as 70 MPa + 535 °C and 120 MPa + 555 °C, respectively. Such requirements lead to achieving transverse induced anisotropy, which also allows forming periodic alignment of transverse domains.