摘要:

Crystalline terbium–iron compounds generate large magnetostrictive strains but for practical application require relatively large fields to overcome magnetocrystalline anisotropy. Their amorphous counterparts are magnetically softer and yet potentially useful magnetostrictive strains are still exhibited due to the presence of the Tb ions. As part of our investigation into the origins and magnitudes of the magnetostriction in amorphous rare earth–iron alloys, their magnetic properties have been subjected to close examination. Melt-spun ribbons ofTbFe2containing between 3 and 14 at. &percent; boron were prepared and shown to be amorphous (>6 at. &percent; B). The field and temperature dependences of magnetization have been measured in the region4.5 K<T<300 Kwith fields up to 5 T using a superconducting quantum interference device magnetometer. The temperature dependences of coercivity and remanence have been determined. Zero field and field cooled magnetization curves indicate a spin freezing temperature ∼240 K. Analyzing the demagnetization curves in terms of the random anisotropy model proposed by Harris, Plischke, and Zuckermann (HPZ) [R. Harris, M. Plischke, and M. J. Zuckermann, Phys. Rev. Lett.31, 160 (1974)] shows that the anisotropy and exchange energy in(TbFe2)1−xBxare of comparable magnitudes. Coupled with the sharp decrease of the anisotropy with increasing temperature this leads to an interesting thermal behavior of the remanence with a local minimum at ∼140 K. Different concentrations of boron seem to have no significant effect on the magnetic properties. Boron acts purely as a “glass former” necessary for producing amorphousTbFe2by rapid cooling. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364675

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The Young’s modulus with magnetic field(&Dgr;Eeffect) has been investigated by the single domain model inFe81B13.5Si3.5C2amorphous ribbon for as-received state. The stress dependence of Young’s modulus was analyzed in terms of the volume fraction of transverse domains, the average internal stress, and transverse anisotropy constant as a function of applied stress, and yielded a good agreement with the experimental results. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364676

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The effects of the exciting magnetic field as well as of the bias magnetic field applied at the exciting or receiving points for Fe77.5Si7.5B15amorphous magnetostrictive wire, used as delay lines, have been investigated. Amorphous wires have been tested in the as-cast state and after the stress-relief process. The increase in the value of the exciting magnetic field leads to an increase in the value of the pulsed voltage output. The maximum values for the pulsed voltage output are obtained for about 5 &mgr;s pulse width and 15 A amplitude of the pulsed exciting current. The dependence of pulsed voltage output on the bias magnetic field at the exciting or receiving points is not monotonic for all tested samples. The maximum response is obtained for about 100–200 A/m and 100–300 A/m bias magnetic field applied in exciting and receiving points, respectively. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364677

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We present a study of the evolution of the magnetic properties and behavior of Fe73.5Cu1Nb3Si13.5B9glass covered wires and wires after glass removal with the annealing temperature up to 600 °C starting from the amorphous state. The changes induced in the magnetic properties of these wires are determined by the stress relief process occurring at temperatures below 550 °C, and by the appearance of the nanosized &agr;-FeSi crystalline grains after annealing for 1 h at 550 °C. The nanocrystalline phase formation leads to an improvement of the soft magnetic properties of these wires—increase of permeability and decrease of the coercive force—but also determines the disappearance of the large Barkhausen effect presented by these wires in the amorphous state. Annealing at temperatures over 550 °C determines a depreciation of the soft magnetic properties of both glass covered wires and wires after glass removal. The magnetic behavior of such wires can be fully explained by taking into account the relaxation of the internal stresses with increasing the annealing temperature as well as the changes in the magnetostriction constant due to the appearance of the nanocrystalline grains. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364678

出版商:AIP    

年代:1997

数据来源: AIP