摘要:

In this paper we present measurements of the field dependence of Young’s modulusE(H) and shear modulusG(H) for amorphous wires of composition Fe77.5B15Si7.5.E(H) was measured by a vibrating reed method andG(H) by means of a torsional pendulum. For as‐cast wire the maximum change in either modulus is about 2%, and the form of the field dependence is consistent with the rotation of moments in the outer sheath from a radial to an axial direction, analogous to the moment rotation model for transversely field annealed ribbons. The small magnitude of the modulus changes is a consequence of the rather high anisotropy of a few kJ/m3associated with the casting stress. The modulus changes in current annealed wires are much greater than in the as‐cast state, with ratiosEmin/Emaxapproaching the largest values found in transversely field annealed ribbons. This is consistent with the reduction of the radial stress by annealing, but also indicates the retention of a substantial proportion of off‐axis moments. The significance of these results in the light of present understanding of domain structure in amorphous wires is discussed.

ISSN:0021-8979    

DOI:10.1063/1.349892

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The magnetization and small signal alternating‐current permeabilities of transverse‐field‐annealed amorphous magnetostrictive wires (Fe77.5B15Si7.5) with a fixed twist of 400 deg/m were examined as a function of applied axial tensile stress and axial direct‐current (dc) currents. We observe multiple‐featured magnetization curves which we attribute to the inverse Wiedemann effect, as well as a near total suppression of the large Barkhausen jumps when a dc current is flowing through the wire. Several properties of the wire depend on stress and would be useful for sensor applications; figures of merit of 1700–2600 for torque sensors were obtained.

ISSN:0021-8979    

DOI:10.1063/1.349893

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The dependence of the magnetic parameters as switching fieldH*, coercive fieldHcand reduced remanencemr, on applied tensile stress &sgr;ahas been studied in current annealed amorphous wires. The switching field increases as &sgr; 1/2ain fully relaxed samples, while in both ‘‘as‐quenched’’ and partially relaxed samples the &sgr; 1/2alaw holds only at high values of &sgr;a. The coercive field increases with &sgr;ain a way similar toH* andmrincreases up to the saturation value. This behavior can be explained by taking into account the different magnetic regions that have been proposed for these wires.

ISSN:0021-8979    

DOI:10.1063/1.349894

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Amorphous wires are prepared by the in‐water quenching technique. This procedure gives rise to local magnetoelastic anisotropies arising from the coupling between frozen‐in internal stresses and magnetostriction. Azimuthal and axial components of internal stresses have been experimentally confirmed by the asymmetry of the Matteucci effect at different applied torques for the Fe77.5Si7.5B15amorphous wire. According to classical theory of elasticity, internal stresses produced by the thermal gradient inside the wire during the quenching have been calculated. The nonzero values of azimuthal and axial stresses have been derived in addition to the well accepted radial stresses. This explains the present experimental results. Remanence and its dependence on tensile and torsional stresses has been also calculated.

ISSN:0021-8979    

DOI:10.1063/1.349895

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

By measurement of &lgr;e,Hc, and &khgr;0, we demonstrate that surface crystallization offers a viable method of controlling the magnetostrictive response of metallic glasses. Peak strains of 60 ppm withHc= 10 A/m and &khgr;0=104can be achieved.

ISSN:0021-8979    

DOI:10.1063/1.349896

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We present data on METGLAS 2605S2 annealed with a combination of dc current and load. The material develops an easy direction at ≳45° to the sample axis, and shows significant magnetostrictive and magnetoelastic response. These results are in contrast to data on material annealed with current or load alone.

ISSN:0021-8979    

DOI:10.1063/1.349897

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The effects of additions of the rare earths (RE) terbium and samarium on the room temperature magnetoelastic properties of amorphous Fe0.82B0.18and Fe0.90Zr0.10have been studied for up to 50 and 10 at. % RE, respectively. As the RE content in the Fe–Zr compounds is raised, the relative permeability increases, as do the Curie temperature, magnetostriction and magnetomechanical coupling. The magnetic phase diagram forFe–Zr–RE derived from magnetization data indicates the transition to a random anisotropy phase, evident at low temperatures in Fe0.90Zr0.10, rapidly rises to near room temperature with the addition of Tb and approaches the Curie temperature near ∼9 at. % Tb. This pattern of behavior is not seen in the Fe–B–RE compounds in which the exchange dominated behavior at room temperature remains essentially unchanged and is accompanied by reductions in permeability and magnetostriction until more than ∼18 at. % RE is included.

ISSN:0021-8979    

DOI:10.1063/1.349898

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Elastic anomalies in an Fe75Pt25single crystal have been investigated by ultrasonic pulse echo and inelastic neutron scattering measurements in the temperature range 200 to 800 K. The single crystal which was grown by the Bridgman–Stockbarger process undergoes a magnetic transition atTc= 370 K and a martensitic transformation atMs= 200 K corresponding to a degree of order ofS=0.7. Both ultrasonics and neutron scattering reveal a softening of the transverse modes belowTc. The excess elastic constants obey anM2law as expected from a local magnetoelastic interaction model. The longitudinal ultrasonic velocities already start to soften at 700 K whereas the neutron data for the same acoustic branch do not show any anomaly down to 200 K. The observedqdependences of the acoustic branches point towards a softening confined to the very center of the Brillouin zone.

ISSN:0021-8979    

DOI:10.1063/1.349899

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Magnetic properties of Y1−xGdxCo3B2withx=0, 0.2, 0.4, 0.6, 0.8, and 1.0 have been studied in a wide temperature range from 4.2 to 1250 K. All compounds studied here have the CeCo3B2‐type structure which is a derivative of theRCo5type one. In this system, the Co atom is nonmagnetic down to 4.2 K and the Curie temperature decreases almost linearly with increasing compositionxand is expected to vanish at aroundx=0 (YCo3B2). For the sample withx=0.2, a spin‐glass freezing point has been found in addition to the usual ferromagnetic Curie temperature. Gd magnetic moments obtained from the saturation magnetizations atT=4.2 K are generally smaller than those obtained from the Curie–Weiss constants in the high‐temperature paramagnetic region, which suggests a slight polarization of the Co atoms antiparallel to the Gd moment in the ferromagnetic region.

ISSN:0021-8979    

DOI:10.1063/1.349900

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

YFe10−xCoxSi2(0≤x≤10) compounds were synthesized and studied by x‐ray and neutron diffraction. The ThMn12‐type structure can be formed in the entire range of composition. Magnetic properties were studied at fields up to 70 kOe in the temperature range of 1.5 K to room temperature. X‐ray‐diffraction analyses of aligned powders indicate that the easy magnetization direction is parallel to thecaxis whenx≤6, and deviates from thecaxis whenx≥ (R18)8. The site preference of Si and Co atoms in the structure was determined by neutron‐diffraction experiments.

ISSN:0021-8979    

DOI:10.1063/1.349901

出版商:AIP    

年代:1991

数据来源: AIP