It is demonstrated that hysteresis in the magnetostriction k is coupled to hysteresis in the magnetization M because of the dependence of the magnetostriction on the magnetization. At the same time, when stress is present, the magnetization is in turn coupled to the behavior of the part of the magnetostriction associated with domain moment rotation. An expression for the magnetostriction is formulated, and numerical modeling results for magnetostriction hysteresis are compared to experimental results. Although some features of the magnetostriction in iron and steel still need additional explanation, the main features of the magnetostriction are accounted for. These include liftoff (failure of the magnetostriction to return to its value in the demagnetized state as the hysteresis loop is cycled) and a magnetostriction increase after flux density B reaches its maximum and starts to decrease. A macromagnetic, multidomain formulation that yields zero magnetostriction in the demagnetized specimen is used. >

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Coupled magnetoelastic theory of magnetic and magnetostrictive hysteresis

Amorphous metals have magnetomechanical properties superior to those of crystalline magnetostrictive materials, and are therefore being considered for a variety of transducer and sensor applications. A simplified model is presented of magnetomechanical coupling in amorphous metal ribbons, showing the relation between magnetomechanical behavior and fundamental material parameters. Although high values of magnetization and magnetostriction are important, it is primarily the low values of magnetic anisotropy achievable that give amorphous metals their outstanding magnetomechanical coupling. The magnitude and homogeneity of this anisotropy is controllable through choice of alloy composition and annealing conditions.



Amorphe Metalle haben bessere magnetomechanische Eigenschaften als kristalline Werkstoffe, und werden deshalb fur Anwendungen als Energieumwandler und Kraftubertrager betrachtet. Ein vereinfachtes Modell der magnetomechanischen Kopplung in amorphen metallischen Bandern wird gegeben, das die Beziehung zwischen magnetomechanischem Verhalten und grundlegenden Parametern des Werkstoffes erkart. Obwohl hohe Werte der Magnetisierung und Magnetostriktion wichtig sind, stammen die hervorragenden magnetomechanischen Kopplungseigenschaften in amorphen Metallen hauptsachlich von den niedrigen Werten der magnetischen Anisotropie. Die Werte und die Homogenitat der Anisotropie werden durch die Legierungszusammensetzung und die Anlasbedingungen kontrolliert.

Magnetomechanical properties of amorphous metals

Magnetic amorphous alloys obtained by rapid quenching of the melt are excellent soft magnetic materials with a wide range of technological applications. They also represent a significant challenge to the scientific understanding of magnetic materials, since most of the existing theories of solids assume lattice periodicity. For these reasons, the magnetic and other properties of amorphous alloys have been very actively studied over the last decade. In recent years increasing attention has been directed to the fundamental understanding of the structural, thermal and magnetic properties of the amorphous alloys. It is not only scientifically but also technologically important to achieve such an understanding, since the amorphous alloys are, in many respects, so different from conventional crystalline magnetic materials. The author attempts to summarise recent progress in research on magnetic amorphous alloys and critically assesses the present level of understanding of this new class of magnetic materials, focusing mostly on the transition-metal-metalloid glasses. He starts with a review of early developments and a discussion on the nature of glasses and glass formation and proceeds to an extensive discussion of their atomic structure, both from the experimental and theoretical points of view.

https://iopscience.iop.org/article/10.1088/0034-4885/47/12/002/pdf

Magnetic amorphous alloys: physics and technological applications

The most remarkable characteristics of metallic glasses as well as their main technological applications are reviewed. Particular interest is focused on stress transducers and magnetic field sensors. The possibility of tailoring transition-metal-metalloid amorphous alloys is analysed and attention is also paid to the role and stability of properties such as a magnetostriction and magnetic anisotropy in connection with such applications.

http://iopscience.iop.org/article/10.1088/0022-3735/21/12/002/pdf

Metallic glasses and sensing applications

Phenomenological model for magnetization, magnetostriction and ΔE effect in field-annealed amorphous ribbons

Amorphous metallic ribbons annealed in transverse fields have enormous magnetoelastic coupling. An integrating magnetometer was used to measure magnetization M as a function of applied field H and tensile stress T in such ribbons, from which is determined the magnetostriction λs. A simple phenomenological model of moment rotation can account for the linear dependence of M as a function of H at T below 7×105 Pa observed in Metglas 2605SC. From the model we extract λs∼27×10−6 and anisotropy K∼38 J/M3. In stressed 2605CO no linear behavior is observed. This work substantiates previous high values obtained for the coupling factor and ΔE effect.

H. T. Savage

Papers

Magnetostriction and magnetic anisotropy of field annealed Metglas* 2605 alloys via dc M‐H loop measurements under stress