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تسجيل مستخدم جديدStress-Dependent Magnetoimpedance in Co-Based Amorphous Wires and Application to Tunable Microwave Composites
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A remarkably strong dependence of magnetoimpedance (MI) on tensile stress has been observed in the microwave frequency range for thin CoMnSiB glass-coated microwires exposed to a special thermal treatment. The MI ratio runs into more than 100% at 0.5-1.5 GHz when the tensile stress of 600 MPa is applied to the wire. It was demonstrated that a large MI change at such high frequencies is related predominantly with the dc magnetization orientation. A host of such microwires incorporated into a dielectric matrix may constitute a new sensing medium that is characterized by the stress-dependent effective permittivity. Such medium can be used for the microwave visualization of the stress distribution inside of a composite structure or on its surface.
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The effect of tensile stress on magnetoimpedance (MI) in CoMnSiB amorphous wires at microwave frequencies (0.5-3 GHz) is investigated both experimentally and theoretically. In the presence of the dc bias magnetic field of the order of the anisotropy
field, the impedance shows very large and sensitive change when the wire is subjected to a tensile stress: 100% and 60% per 180 MPa for frequencies 500 MHz and 2.5 GHz, respectively. It is demonstrated that this behavior owes mainly to the directional change in the equilibrium magnetization caused by the applied stress and field, which agrees well with the theoretical results for the surface impedance. This stress effect on MI is proposed to use for creating microwave stress-tunable composite materials containing short magnetic wires. The analysis of the dielectric response from such materials shows that depending on the stress level in the material, the dispersion of the effective permittivity can be of a resonant or relaxation type with a considerable change in its values (up to 100% at 600 MPa). This media can be used for structural stress monitoring by microwave contrast imaging.
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