faxiang qin | National Institute for Materials Science (original) (raw)

Papers by faxiang qin

Research paper thumbnail of Optimization of magnetoimpedance and stress-impedance effects in single-microwire polymer composites for stress monitoring

The influence of applied stress and the composite geometry on impedance properties of composites ... more The influence of applied stress and the composite geometry on impedance properties of composites containing ferromagnetic microwires has been investigated. The results indicate that the application of tensile stress along the microwire axis and the increase of composite thickness decreased the magneto-impedance (MI) ratio. The stress induced impedance (SI) effect was enhanced with increasing composite thickness reflecting the role of the internal residual stresses. Theoretically calculated matrix-wire interfacial stress from the magneto-impedance profiles is in good agreement with the value of the applied effective tensile stress. This demonstrates a new route to probing the stress conditions of such composites.

Research paper thumbnail of Mechanical-electromagnetic coupling of microwire polymer composites at microwave frequencies

Applied Physics Letters, 2010

We have fabricated a set of microwire composites with varying wire concentrations and studied the... more We have fabricated a set of microwire composites with varying wire concentrations and studied their effective complex permittivity under the tensile stress at a frequency range of 1-6 GHz. It has been found that with increasing wire concentration the composite presents increasing effective permittivity and strain sensitivity. The Gaussian molecular network model shows a complex strain dependence of sensitivity due to the composite architecture influenced by the wire concentrations. All these results indicate the proposed composite are excellent candidate materials for the microwave sensing and structural interrogation applications.

Research paper thumbnail of Influence of varying metal-to-glass ratio on GMI effect in amorphous glass-coated microwires

Solid State Communications, 2010

The influence of a varying metal-to-glass ratio on the GMI effect in amorphous glass-coated Co 70... more The influence of a varying metal-to-glass ratio on the GMI effect in amorphous glass-coated Co 70.3 Fe 3.7 B 10 Si 13 Cr 3 microwires has been investigated. In the range of frequencies investigated (1-10 MHz), the magnitude of the GMI effect increases as the metal-to-glass ratio (h) increases from 4.11 to 9.29. The GMI curves for the h = 4.11 microwire exhibit a single-peak feature for f ≤ 1 MHz and a double-peak feature for f > 1 MHz, whereas a consistent double-peak feature is observed for microwires with h = 8.07, 8.72, and 9.29. The largest GMI effect is achieved for microwires with h = 9.29. The anisotropy field (H k ), determined from GMI curves, increases with h = 4.11 to h = 8.07 and decreases when h > 8.07. The calculated radial stress decreases as h increases from 4.11 to 9.29. These results provide further insights into the correlation between the GMI effect and microwire dimensions towards the GMI optimization of amorphous glass-coated magnetic microwires for sensor applications.

Research paper thumbnail of Wire-length effect on GMI in Co 70.3Fe 3.7B 10Si 13Cr 3 amorphous glass-coated microwires

Materials Science and Engineering B-advanced Functional Solid-state Materials, 2010

Research paper thumbnail of Smart Composites With Short Ferromagnetic Microwires for Microwave Applications

IEEE Transactions on Magnetics, 2011

Smart composites with short-cut Co 68 7 Fe 4 Ni 1 B 13 Si 11 Mo 2 3 microwires were prepared and ... more Smart composites with short-cut Co 68 7 Fe 4 Ni 1 B 13 Si 11 Mo 2 3 microwires were prepared and studied in terms of their microwave tunable properties. It is shown that the frequency dependence of effective permittivity relaxes with the application of magnetic field till around the anisotropy field of the microwire due to the increase of internal losses. There exists a significant field tunable effect in the transmission and reflection spectra, featured as a resonance-relaxation transformation; a step-like shift of reflection phase was also observed with increasing applied magnetic field, which can be exploited especially for the sensing applications such as field/stress monitoring.

Research paper thumbnail of Large GMI effect in Co-rich amorphous wire by tensile stress

Journal of Magnetism and Magnetic Materials, 2011

Quality Co68Fe4.5Si15B12.5 amorphous wires are fabricated and their giant magneto impedance (GMI)... more Quality Co68Fe4.5Si15B12.5 amorphous wires are fabricated and their giant magneto impedance (GMI) effect are investigated at frequencies ranging from 0.1 to 20 MHz with or without tensile stress applied. Experimental results indicate that the GMI effect of these wires can be effectively improved by applying a small axial tensile stress. There is a pronounced increase from 1.3% to 47.3% in impedance ratio at 0.6 MHz when a stress of 103 MPa is applied. The GMI response is further increased to 261% by doing so at 15 MHz. The field sensitivity of these wires is optimized and it increases from 0.55 to 2.73%/(A/m) at 0.6 MHz and it is proved that the most sensitive field response is obtained by applying a tensile stress of 84.5 MPa below 1 MHz. With reference to the stress evolution of sensitivity at varying frequencies, the maximum field sensitivity shifts to a lower stress with increasing frequency. Quantitatively, a stress as small as 18.4 MPa is enough to yield a field sensitivity as high as 6.7%/(A/m) at 15 MHz. This demonstrates the possibility of achieving small stress (<100 MPa) induced large enhancement of GMI effect and field sensitivity at frequencies of several tens of MHz that are of much technical interest in sensor applications.► It is interesting that results prove GMI effect can be effectively improved by these tensile stresses. ► The GMI response of these Co-rich amorphous wires is very sensitive. ► Their field sensitivity can be as much as 6.7%/(A/m) at 15 MHz, which is larger than 4%/(A/m) as reported (Ref. [4]).

Research paper thumbnail of Giant magneto-impedance and stress-impedance effects of microwire composites for sensing applications

Solid State Communications, 2011

Composites consisting of glass-coated amorphous microwire Co 68.59 Fe 4.84 Si 12.41 B 14.16 and 9... more Composites consisting of glass-coated amorphous microwire Co 68.59 Fe 4.84 Si 12.41 B 14.16 and 913 E-glass prepregs were designed and fabricated. The influences of tensile stress, annealing and number of composite layers on the giant magneto-impedance (GMI) and giant stress-impedance (GSI) effects in these composites were investigated systematically. It was found that the application of tensile stress along the microwire axis or an increase in the number of composite layers reduced the GMI effect and increased the circular anisotropy field, while the annealing treatment had a reverse effect. The value of matrix-wire interfacial stress calculated via the GMI profiles coincided with the value of the applied effective tensile stress to yield similar GMI profiles. Enhancement of the GSI effect was achieved in the composites relative to their single microwire inclusion. These findings are important for the development of functional microwire-based composites for magnetic-and stress-sensing applications. They also open up a new route for probing the interfacial stress in fibre-reinforced polymer (FRP) composites.

Research paper thumbnail of The effect of La addition on optical transmittance spectra of hydrogenated Mg-La thin films

Journal of Applied Physics, 2008

This paper reported that the transmission of hydrogenated Mg-La films is influenced by the conten... more This paper reported that the transmission of hydrogenated Mg-La films is influenced by the content of La dissolved in Mg. With the increase in La:Mg atomic ratio, the transmission decreases and the short wavelength limit of the transmission spectra shifts toward the long wavelength side. This phenomenon is well explained by using the Lambert-Beer law according to the band gap change, which was calculated using CASTEP module caused by dissolving of La.

Research paper thumbnail of Ferromagnetic microwires enabled polymer composites for sensing applications

Composites Part A-applied Science and Manufacturing, 2010

In the present work, sensing functionalities are introduced into structural composites via embedd... more In the present work, sensing functionalities are introduced into structural composites via embedded magnetic microwires. A systematic study on the structure and functionalities of microwires and their composites is performed. The single-wire composite shows a significant giant magnetoimpedance (GMI) effect of up to 320% in a frequency range of 1-100 MHz due to stress enhanced transverse magnetoanisotropy. With increasing quantities of embedded wires from 1 to 3, the maximum GMI ratio is enhanced significantly by more than 35%, making the resultant composite favourable for field sensing applications. The microwire-composite also shows superior stress-sensing resolution as high as 134.5 kHz/microstrain, which is about 26 times higher than the recently proposed SRR-based sensor. As evidenced by the structural examination and tensile tests, the extremely small volume fraction of microwires ($0.01 vol.%) allows the wire-composites to retain their mechanical integrity and performance.

Research paper thumbnail of Stress tunable microwave absorption of ferromagnetic microwires for sensing applications

Journal of Alloys and Compounds, 2011

ABSTRACT In the present work, we have studied the low field absorption (LFA) at 9GHz of a set of ... more ABSTRACT In the present work, we have studied the low field absorption (LFA) at 9GHz of a set of Co-based glass-coated microwires in the presence of tensile stresses along the wire axis. The results reveal that the absorption profiles bear valve-like features associated with microwave magnetoimpedance effect. The stress applied along the wire axis compensates the reverse effect of magnetic field on absorption. The peak shown in the derivative LFA spectra becomes wider with increasing stress and moves to higher field, corresponding to the magnetization process. A larger ratio of metal to total diameter was found to be favorable to microwave absorption due to the smaller anisotropy and also gave rise to a larger magnetostriction constant. The influences of stress/magnetic field on the absorption as well as the shift of feature stress with wire geometry were discussed in the context of an effective microwire-based sensor design. Calculations of magnetostriction constant by the derived field dependence of anisotropy field were also performed to demonstrate the usefulness of stress tunable microwave absorption characteristics as a research tool.

Research paper thumbnail of Stress tunable properties of ferromagnetic microwires and their multifunctional composites

Journal of Applied Physics, 2011

We report the results of a systematic study on stress tunable absorption of glass-coated amorphou... more We report the results of a systematic study on stress tunable absorption of glass-coated amorphous Co68.7Fe4Ni1B13Si11Mo2.3 microwires and their composites. The magnetic microwires possess good stress-impedance properties and yield a stress dependence of absorption at gigahertz frequencies. The stress compensates the reverse effect of magnetic field on absorption. There exist strong stress dependences of the effective permittivity and transmission parameters. Composite failure due to the wire damage results in a dramatic change of the sign and magnitude of effective permittivity. The double peak is identified in the stress dependence of field tunability, in contrast to the single peak for the magnetic field tunability. All these results indicate that the present composites are very promising for detecting the ambient stress levels and interrogating the structural integrity.

Research paper thumbnail of Exceptional electromagnetic interference shielding properties of ferromagnetic microwires enabled polymer composites

Journal of Applied Physics, 2010

We report the results of a systematic study of the magnetic, mechanical, magnetoimpedance and fie... more We report the results of a systematic study of the magnetic, mechanical, magnetoimpedance and field tunable properties of glass-coated amorphous Co 68.7 Fe 4 Ni 1 B 13 Si 11 Mo 2.3 microwires and composites containing these microwires. The magnetic microwires possess good magnetic and mechanical properties. The magnetoimpedance ratio in the gigahertz range varies sensitively with applied fields below the anisotropy field but becomes unchanged for higher applied fields. The good mechanical properties are retained in the magnetic microwires-embedded composites. The strong field dependences of the effective permittivity and transmission parameters in the gigahertz range indicate that the present composites are very promising candidate materials for structural health monitoring and self-sensing applications.

Research paper thumbnail of Co-based magnetic microwire and field-tunable multifunctional macro-composites

Journal of Non-crystalline Solids, 2009

Structural, magnetic and mechanical properties of Co-based magnetic microwires and their composit... more Structural, magnetic and mechanical properties of Co-based magnetic microwires and their composites had been investigated. It was found that annealing amorphous microwires at 600 °C caused a drastic variation in the amorphous structure due to crystallization and consequently degraded the soft magnetic properties of the microwires. The tensile tests on the single microwires of different size with and without glass-coated layer revealed a coherent correlation between the mechanical properties and the wire geometry. When compared with single magnetic microwires, the magnetic and magneto-impedance properties of composites were much improved. The strong field dependence of the effective permittivity and transmission/reflection parameters in the Gigahertz range of the composites containing short wires or arrays of continuous wires indicated that these new composites are promising candidate materials for a variety of self-sensing applications.

Research paper thumbnail of Novel magnetic microwires-embedded composites for structural health monitoring applications

Journal of Applied Physics, 2010

We report the results of a systematic study of the magnetic, mechanical, magnetoimpedance and fie... more We report the results of a systematic study of the magnetic, mechanical, magnetoimpedance and field tunable properties of glass-coated amorphous Co 68.7 Fe 4 Ni 1 B 13 Si 11 Mo 2.3 microwires and composites containing these microwires. The magnetic microwires possess good magnetic and mechanical properties. The magnetoimpedance ratio in the gigahertz range varies sensitively with applied fields below the anisotropy field but becomes unchanged for higher applied fields. The good mechanical properties are retained in the magnetic microwires-embedded composites. The strong field dependences of the effective permittivity and transmission parameters in the gigahertz range indicate that the present composites are very promising candidate materials for structural health monitoring and self-sensing applications.

Research paper thumbnail of Optimization of magnetoimpedance and stress-impedance effects in single-microwire polymer composites for stress monitoring

The influence of applied stress and the composite geometry on impedance properties of composites ... more The influence of applied stress and the composite geometry on impedance properties of composites containing ferromagnetic microwires has been investigated. The results indicate that the application of tensile stress along the microwire axis and the increase of composite thickness decreased the magneto-impedance (MI) ratio. The stress induced impedance (SI) effect was enhanced with increasing composite thickness reflecting the role of the internal residual stresses. Theoretically calculated matrix-wire interfacial stress from the magneto-impedance profiles is in good agreement with the value of the applied effective tensile stress. This demonstrates a new route to probing the stress conditions of such composites.

Research paper thumbnail of Mechanical-electromagnetic coupling of microwire polymer composites at microwave frequencies

Applied Physics Letters, 2010

We have fabricated a set of microwire composites with varying wire concentrations and studied the... more We have fabricated a set of microwire composites with varying wire concentrations and studied their effective complex permittivity under the tensile stress at a frequency range of 1-6 GHz. It has been found that with increasing wire concentration the composite presents increasing effective permittivity and strain sensitivity. The Gaussian molecular network model shows a complex strain dependence of sensitivity due to the composite architecture influenced by the wire concentrations. All these results indicate the proposed composite are excellent candidate materials for the microwave sensing and structural interrogation applications.

Research paper thumbnail of Influence of varying metal-to-glass ratio on GMI effect in amorphous glass-coated microwires

Solid State Communications, 2010

The influence of a varying metal-to-glass ratio on the GMI effect in amorphous glass-coated Co 70... more The influence of a varying metal-to-glass ratio on the GMI effect in amorphous glass-coated Co 70.3 Fe 3.7 B 10 Si 13 Cr 3 microwires has been investigated. In the range of frequencies investigated (1-10 MHz), the magnitude of the GMI effect increases as the metal-to-glass ratio (h) increases from 4.11 to 9.29. The GMI curves for the h = 4.11 microwire exhibit a single-peak feature for f ≤ 1 MHz and a double-peak feature for f > 1 MHz, whereas a consistent double-peak feature is observed for microwires with h = 8.07, 8.72, and 9.29. The largest GMI effect is achieved for microwires with h = 9.29. The anisotropy field (H k ), determined from GMI curves, increases with h = 4.11 to h = 8.07 and decreases when h > 8.07. The calculated radial stress decreases as h increases from 4.11 to 9.29. These results provide further insights into the correlation between the GMI effect and microwire dimensions towards the GMI optimization of amorphous glass-coated magnetic microwires for sensor applications.

Research paper thumbnail of Wire-length effect on GMI in Co 70.3Fe 3.7B 10Si 13Cr 3 amorphous glass-coated microwires

Materials Science and Engineering B-advanced Functional Solid-state Materials, 2010

Research paper thumbnail of Smart Composites With Short Ferromagnetic Microwires for Microwave Applications

IEEE Transactions on Magnetics, 2011

Smart composites with short-cut Co 68 7 Fe 4 Ni 1 B 13 Si 11 Mo 2 3 microwires were prepared and ... more Smart composites with short-cut Co 68 7 Fe 4 Ni 1 B 13 Si 11 Mo 2 3 microwires were prepared and studied in terms of their microwave tunable properties. It is shown that the frequency dependence of effective permittivity relaxes with the application of magnetic field till around the anisotropy field of the microwire due to the increase of internal losses. There exists a significant field tunable effect in the transmission and reflection spectra, featured as a resonance-relaxation transformation; a step-like shift of reflection phase was also observed with increasing applied magnetic field, which can be exploited especially for the sensing applications such as field/stress monitoring.

Research paper thumbnail of Large GMI effect in Co-rich amorphous wire by tensile stress

Journal of Magnetism and Magnetic Materials, 2011

Quality Co68Fe4.5Si15B12.5 amorphous wires are fabricated and their giant magneto impedance (GMI)... more Quality Co68Fe4.5Si15B12.5 amorphous wires are fabricated and their giant magneto impedance (GMI) effect are investigated at frequencies ranging from 0.1 to 20 MHz with or without tensile stress applied. Experimental results indicate that the GMI effect of these wires can be effectively improved by applying a small axial tensile stress. There is a pronounced increase from 1.3% to 47.3% in impedance ratio at 0.6 MHz when a stress of 103 MPa is applied. The GMI response is further increased to 261% by doing so at 15 MHz. The field sensitivity of these wires is optimized and it increases from 0.55 to 2.73%/(A/m) at 0.6 MHz and it is proved that the most sensitive field response is obtained by applying a tensile stress of 84.5 MPa below 1 MHz. With reference to the stress evolution of sensitivity at varying frequencies, the maximum field sensitivity shifts to a lower stress with increasing frequency. Quantitatively, a stress as small as 18.4 MPa is enough to yield a field sensitivity as high as 6.7%/(A/m) at 15 MHz. This demonstrates the possibility of achieving small stress (<100 MPa) induced large enhancement of GMI effect and field sensitivity at frequencies of several tens of MHz that are of much technical interest in sensor applications.► It is interesting that results prove GMI effect can be effectively improved by these tensile stresses. ► The GMI response of these Co-rich amorphous wires is very sensitive. ► Their field sensitivity can be as much as 6.7%/(A/m) at 15 MHz, which is larger than 4%/(A/m) as reported (Ref. [4]).

Research paper thumbnail of Giant magneto-impedance and stress-impedance effects of microwire composites for sensing applications

Solid State Communications, 2011

Composites consisting of glass-coated amorphous microwire Co 68.59 Fe 4.84 Si 12.41 B 14.16 and 9... more Composites consisting of glass-coated amorphous microwire Co 68.59 Fe 4.84 Si 12.41 B 14.16 and 913 E-glass prepregs were designed and fabricated. The influences of tensile stress, annealing and number of composite layers on the giant magneto-impedance (GMI) and giant stress-impedance (GSI) effects in these composites were investigated systematically. It was found that the application of tensile stress along the microwire axis or an increase in the number of composite layers reduced the GMI effect and increased the circular anisotropy field, while the annealing treatment had a reverse effect. The value of matrix-wire interfacial stress calculated via the GMI profiles coincided with the value of the applied effective tensile stress to yield similar GMI profiles. Enhancement of the GSI effect was achieved in the composites relative to their single microwire inclusion. These findings are important for the development of functional microwire-based composites for magnetic-and stress-sensing applications. They also open up a new route for probing the interfacial stress in fibre-reinforced polymer (FRP) composites.

Research paper thumbnail of The effect of La addition on optical transmittance spectra of hydrogenated Mg-La thin films

Journal of Applied Physics, 2008

This paper reported that the transmission of hydrogenated Mg-La films is influenced by the conten... more This paper reported that the transmission of hydrogenated Mg-La films is influenced by the content of La dissolved in Mg. With the increase in La:Mg atomic ratio, the transmission decreases and the short wavelength limit of the transmission spectra shifts toward the long wavelength side. This phenomenon is well explained by using the Lambert-Beer law according to the band gap change, which was calculated using CASTEP module caused by dissolving of La.

Research paper thumbnail of Ferromagnetic microwires enabled polymer composites for sensing applications

Composites Part A-applied Science and Manufacturing, 2010

In the present work, sensing functionalities are introduced into structural composites via embedd... more In the present work, sensing functionalities are introduced into structural composites via embedded magnetic microwires. A systematic study on the structure and functionalities of microwires and their composites is performed. The single-wire composite shows a significant giant magnetoimpedance (GMI) effect of up to 320% in a frequency range of 1-100 MHz due to stress enhanced transverse magnetoanisotropy. With increasing quantities of embedded wires from 1 to 3, the maximum GMI ratio is enhanced significantly by more than 35%, making the resultant composite favourable for field sensing applications. The microwire-composite also shows superior stress-sensing resolution as high as 134.5 kHz/microstrain, which is about 26 times higher than the recently proposed SRR-based sensor. As evidenced by the structural examination and tensile tests, the extremely small volume fraction of microwires ($0.01 vol.%) allows the wire-composites to retain their mechanical integrity and performance.

Research paper thumbnail of Stress tunable microwave absorption of ferromagnetic microwires for sensing applications

Journal of Alloys and Compounds, 2011

ABSTRACT In the present work, we have studied the low field absorption (LFA) at 9GHz of a set of ... more ABSTRACT In the present work, we have studied the low field absorption (LFA) at 9GHz of a set of Co-based glass-coated microwires in the presence of tensile stresses along the wire axis. The results reveal that the absorption profiles bear valve-like features associated with microwave magnetoimpedance effect. The stress applied along the wire axis compensates the reverse effect of magnetic field on absorption. The peak shown in the derivative LFA spectra becomes wider with increasing stress and moves to higher field, corresponding to the magnetization process. A larger ratio of metal to total diameter was found to be favorable to microwave absorption due to the smaller anisotropy and also gave rise to a larger magnetostriction constant. The influences of stress/magnetic field on the absorption as well as the shift of feature stress with wire geometry were discussed in the context of an effective microwire-based sensor design. Calculations of magnetostriction constant by the derived field dependence of anisotropy field were also performed to demonstrate the usefulness of stress tunable microwave absorption characteristics as a research tool.

Research paper thumbnail of Stress tunable properties of ferromagnetic microwires and their multifunctional composites

Journal of Applied Physics, 2011

We report the results of a systematic study on stress tunable absorption of glass-coated amorphou... more We report the results of a systematic study on stress tunable absorption of glass-coated amorphous Co68.7Fe4Ni1B13Si11Mo2.3 microwires and their composites. The magnetic microwires possess good stress-impedance properties and yield a stress dependence of absorption at gigahertz frequencies. The stress compensates the reverse effect of magnetic field on absorption. There exist strong stress dependences of the effective permittivity and transmission parameters. Composite failure due to the wire damage results in a dramatic change of the sign and magnitude of effective permittivity. The double peak is identified in the stress dependence of field tunability, in contrast to the single peak for the magnetic field tunability. All these results indicate that the present composites are very promising for detecting the ambient stress levels and interrogating the structural integrity.

Research paper thumbnail of Exceptional electromagnetic interference shielding properties of ferromagnetic microwires enabled polymer composites

Journal of Applied Physics, 2010

We report the results of a systematic study of the magnetic, mechanical, magnetoimpedance and fie... more We report the results of a systematic study of the magnetic, mechanical, magnetoimpedance and field tunable properties of glass-coated amorphous Co 68.7 Fe 4 Ni 1 B 13 Si 11 Mo 2.3 microwires and composites containing these microwires. The magnetic microwires possess good magnetic and mechanical properties. The magnetoimpedance ratio in the gigahertz range varies sensitively with applied fields below the anisotropy field but becomes unchanged for higher applied fields. The good mechanical properties are retained in the magnetic microwires-embedded composites. The strong field dependences of the effective permittivity and transmission parameters in the gigahertz range indicate that the present composites are very promising candidate materials for structural health monitoring and self-sensing applications.

Research paper thumbnail of Co-based magnetic microwire and field-tunable multifunctional macro-composites

Journal of Non-crystalline Solids, 2009

Structural, magnetic and mechanical properties of Co-based magnetic microwires and their composit... more Structural, magnetic and mechanical properties of Co-based magnetic microwires and their composites had been investigated. It was found that annealing amorphous microwires at 600 °C caused a drastic variation in the amorphous structure due to crystallization and consequently degraded the soft magnetic properties of the microwires. The tensile tests on the single microwires of different size with and without glass-coated layer revealed a coherent correlation between the mechanical properties and the wire geometry. When compared with single magnetic microwires, the magnetic and magneto-impedance properties of composites were much improved. The strong field dependence of the effective permittivity and transmission/reflection parameters in the Gigahertz range of the composites containing short wires or arrays of continuous wires indicated that these new composites are promising candidate materials for a variety of self-sensing applications.

Research paper thumbnail of Novel magnetic microwires-embedded composites for structural health monitoring applications

Journal of Applied Physics, 2010

We report the results of a systematic study of the magnetic, mechanical, magnetoimpedance and fie... more We report the results of a systematic study of the magnetic, mechanical, magnetoimpedance and field tunable properties of glass-coated amorphous Co 68.7 Fe 4 Ni 1 B 13 Si 11 Mo 2.3 microwires and composites containing these microwires. The magnetic microwires possess good magnetic and mechanical properties. The magnetoimpedance ratio in the gigahertz range varies sensitively with applied fields below the anisotropy field but becomes unchanged for higher applied fields. The good mechanical properties are retained in the magnetic microwires-embedded composites. The strong field dependences of the effective permittivity and transmission parameters in the gigahertz range indicate that the present composites are very promising candidate materials for structural health monitoring and self-sensing applications.