Effect of Tension Annealing Induced-anisotropy on Magnetic Properties of Nanocrystalline Alloy

The samples of Fe74.1Cu1Nb3Si15B6.9 (atomic fraction, %) nanocrystalline alloy were subjected to continuous tension annealing treatment, while the effect of the continuous tension annealing induced-anisotropy on their structure and magnetic properties was investigated. The results show that the induced anisotropy constant (K u) and annealing tension (σ) fit linear relationship in the presence of tensile stress. The effective permeability (μ e) at test points f =5 kHz and H =3 A/m first increased and then decreased with the increase of annealing tension. The increase of annealing tension decelerate the process of effective permeability (μ e) attenuation, which can remain constant over a wide range of magnetic field and frequency. Compared with other samples, the effective permeability (μ e) of the alloy is nearly 800 in the testing range of 0~800 A/m (magnetic field) and 1 k~1 MHz (frequency) when tensile stress is 67 MPa. That show the tension annealed alloy has an excellent constant permeable property. Otherwise, with the increase of annealing tension the unit mass loss of the alloy decreases. When tensile stress is 67 MPa the unit mass loss of the alloy approximates 68 W/kg (testing condition: B m=300 mT, f =100 kHz), which reduces nearly 67% compared with the absence of annealing tension. Besides, the 180° stripe magnetic domain observed by magneto-optical Kerr microscopy is perpendicular to the tensile stress on the alloy. The increase of tensile stress leads to decrease of the width of domain structures in the alloy and tends to comparable. When tensile stress is 67 MPa the width of domain structures is about 85 μm. © 2020, Editorial Office of Chinese Journal of Materials Research. All right reserved.