[en] A polyvinylidene fluoride (PVDF) piezosensor was installed as an integral part of an ultrasonic wire-bonding transducer for measuring bonding parameters, such as impact force, ultrasonic amplitude, and bond time. Four different types of electrode patterns were used to optimize the sensor outputs. When the ring-shaped electrode of the sensor was subdivided into four different sections, namely the top, bottom, left, and right sections, different output signals were observed during the wire-bonding process. The top section of the sensor was more sensitive to the impact force while the left and right sections could track the changes in the ultrasonic amplitude proficiently. This sensor has good potential to be used in an in situ automatic wire-bonding process-control system

[en] The dynamic magnetomechanical properties of Sm_0.88Dy_0.12Fe_1.93/epoxy composites with 51vol% Sm_0.88Dy_0.12Fe_1.93 particles were investigated. The dynamic relative permeability (μ_r33) showed a flat response with frequency for all bias fields (H_Bias) apart from the fundamental-shape-resonance-induced variations in the vicinity of 42kHz. The free (μ_r33^T) and clamped (μ_r33^S) permeabilities attained their maximum values at H_Bias=20kA/m. The elastic modulus at constant field strength (E₃^H) and that at constant flux density (E₃^B) exhibited a steady negative -ΔE effect for H_Bias=<240kA/m. The dynamic strain coefficient (d₃₃) displayed a broad negative maximum around H_Bias=180kA/m

[en] A two-phase magnetoelectric (ME) parallel sandwich was developed by bonding two longitudinally magnetized Terfenol-D/epoxy pseudo-1-3 magnetostrictive composite plates on two longitudinally polarized PZT/epoxy 2-2 piezoelectric composite plates combined longitudinally as a single plate and with their polarization directions arranged in reverse directions. A significantly large ME voltage sensitivity (ME _V ) of 3.1 V/Oe was observed at the resonance frequency of 42.8 kHz under a relatively low bias field of 0.8 kOe. This resonance ME _V was ∼35 times larger than its nonresonance values, showing great promise of using the proposed sandwich in ME conversion devices

[en] A novel composite of brass ring and PZT disk shows a high dc magnetic field (H_dc) response when using the product effect of the Lorentz force effect from a metal ring in a dc magnetic field applied with ac electrical current, and the piezoelectric effect of piezoelectric material. The output voltage between the two faces of PZT shows a good linear response to the dc magnetic field (<1 kOe) under different ac electrical current inputs (<300 mA). The magnetoelectric coefficient is about ∝33.2 mV/T A. Simultaneously, the magnitude of its magnetoelectric coefficient can be manually controlled by an applied electrical current. This composite has the potential for applications in magnetoelectric transducers and sensors that work without coils even for static magnetic fields. (orig.)

[en] Stabilizer (B, Co)-free, light rare earth (Pr)-substituted Laves alloys (Tb_0.3Dy_0.7)_1-xPr_xFe_1.55 (0 ≤ x ≤ 0.4) are synthesized, and their structural, magnetic, and magnetostrictive properties are investigated. X-ray diffraction analysis confirms the presence of single cubic Laves phase with an MgCu₂-type structure in the (Tb_0.3Dy_0.7)_1-xPr_xFe_1.55 alloys with 0 ≤ x ≤ 0.35. The lattice parameter a of the Laves phase increases, while the Curie temperature decreases, with increasing x from 0 to 0.35. The saturation magnetization of the alloys decreases with increasing x. The linear anisotropic magnetostriction λ_a (=λ_|| - λ_{perpendicular)} shows a maximum of 1502 ppm at x = 0.25 as a result of the magnetocrystalline anisotropy compensation.

[en] Pseudo-1-3 magnetostrictive composites of 0.5 volume fraction are fabricated by embedding and aligning stabilizer (B, Co)-free, light rare earth (Pr)-contained magnetostrictive (Tb_0.3Dy_0.7)_1-xPr_xFe_1.55 (0 ≤ x ≤ 0.4) particles with a size distribution of 10-300 μm in a passive epoxy matrix. The dynamic magnetomechanical properties of the composites with different Pr content x are investigated as a function of both bias field (=10-200 kA/m) and frequency (=25 Hz-70 kHz). The composites show similar qualitative trends in properties for all x with no frequency dispersion effect except for the resonance range. The dynamic relative permeability μ_r33^T demonstrates a decreasing trend with increasing x for the whole range of bias field due to the weakening of saturation magnetization with increasing Pr content. The two elastic moduli E₃^H and E₃^B, which result in negative-ΔE with maximum dynamic strain coefficient d₃₃ and dynamic magnetomechanical coupling coefficient k₃₃ near 140 kA/m bias in all composites, decrease with increasing x for all biases owing to the increasing compliance contribution from Pr. The (Tb_0.3Dy_0.7)_0.75Pr_0.25Fe_1.55 composite exhibits the largest d₃₃ and k₃₃ at 140 kA/m bias as a result of the compensation for magnetocrystalline anisotropy.

[en] Pseudo-1-3 magnetostrictive composites of approximately 0.6 volume-fraction Sm_0.88Dy_0.12Fe_1.93 particles and epoxy were fabricated, and their quasi-static and dynamic magnetoelastic properties were investigated. The dynamic relative permeability (μ_r33) exhibited a flat response with frequency, except for the variation associated with the fundamental shape resonance of the samples at about 46kHz. Both μ_r33^T (at constant stress) and μ_r33^S (at constant strain) reached their maximum values at a magnetic bias field (H_Bias) of about 20kA/m due to the relatively easy 180 deg. domain-wall motion. The two elastic moduli, E₃^H (at constant magnetic field strength) and E₃^B (at constant magnetic flux density), showed a small decrease with increasing H_Bias with no trace of negative-ΔE effect in the H_Bias range of 5-240kA/m. The saturation magnetostriction (λ_S) was not attained at the highest available field level, reflecting the existence of relatively high magnetocrystalline anisotropy in the material. The dynamic strain coefficient (d₃₃) displayed a broad negative maximum around H_Bias=180kA/m as a result of the maximum motion of non-180 deg. domain walls