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Journal of Physics: Conference Series
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Study of inverse magnetostrictive effect in metallic glasses Fe80−
x
Co
x
P14B6
To cite this article: V S Severikov et al 2017 J. Phys.: Conf. Ser. 929 012049
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International Conference PhysicA.SPb/2016 IOP Publishing
IOP Conf. Series: Journal of Physics: Conf. Series 929 (2017) 012049 doi :10.1088/1742-6596/929/1/012049
Study of inverse magnetostrictive effect in metallic glasses
Fe80-xCoxP14B6
V S Severikov1, A M Grishin1,2, V S Ignahin1
1 Petrozavodsk State University, 185910 Petrozavodsk, Karelian Republic, Russia
2 KTH Royal Institute of Technology, SE-164 40 Stockholm-Kista, Sweden
E-mail: severva3@gmail.com
Abstract. The paper presents the possibility to build a tension gauge capable to discriminate
different kinds of deformations: compression and twisting (induced by torsion strain) based on
the magnetoelastic effect in new metallic glasses Fe80-xCoxP14B6. Applied loads increase
coercive field Hc, saturation induction Bs and rectangularity of magnetic hysteresis loop. For
example, hysteresis loop traced for 1 mm narrow, 50 cm long and 30 μm thick Fe40Co40P14B6
straight ribbon subjected to longitudinal stress of 346 MPa shown increased Bs from 1.24 to 1.7
T and squareness from 0.55 to 0.88 compared to unloaded specimen. For twisting, on the
contrary, both squareness and coercive field vary whereas the value of Bs remains unchanged.
1. Introduction
Magnetic properties of rapid quenched Fe80-xCoxP14B6 metallic glasses surpass characteristics of
Fe40Ni40P14B6 magnetosoft material (Metglas 2826) widespread in the commercial market. Really, the
maximum relative differential permeability of as quenched Fe80-xCoxP14B6 ribbons is about 110000, the
saturation induction Bs = 1.45 T, quasistatic coercive field as low as 4 A/m, Curie temperature above
700 K, significantly higher thermal stability due to increased by 60 K crystallization temperatures, low
hysteresis loss of about 0.26 W/kg in the saturation mode at frequency of 100 Hz [1-3].
Magnetostriction and inverse magnetostrictive (magnetoelastic) effect have been thoroughly
investigated only in some polycrystalline magnetic materials. Due to versatile functional properties
amorphous magnetic materials promise many practical applications. Besides high magnetoelastic
coupling, they exhibit large elastic thresholds, which permit the application of much larger stresses not
accompanied by plastic deformations.
The aim of this article is to report experimental results on magneto-mechanical effect in amorphous
rapidly quenched ribbons with different Fe80-xCoxP14B6 compositions.
2. Experimental
Series of Fe80-xCoxP14B6 (x = 25, 32, 35 and 40 at.%) ribbons were meltspun onto the massive copper
wheel from the RF-melted superheated master ingots. X-ray diffraction reveals amorphous structure in
as-cast specimens containing the superposition of bcc α-FeCo and bct (Fe,Co)3(P,B) nuclei with a
characteristic size as small as 1.6 nm. Both isothermal and isochronal annealing of ribbons in
protective atmosphere lead to the predominant growth of bcc α-FeCo 20-30 nm-sized crystals within
the amorphous metallic matrix [4].
Characteristics that quantify magnetoelastic phenomenon were obtained from the series of hysteresis
B-H loops recorded for Fe80-xCoxP14B6 ribbons under applied external stresses. Due to very high
magnetic permeability, special precautions were undertaken to choose a proper orientation of ribbons
in 30 cm long primary and 5 cm long two secondary (pick-up and reference) solenoidal coils of the
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magnetometer. It is determined by actual magnetic declination of 12.764° E and relatively high
magnetic inclination of 74.797° in Petrozavodsk city (Karelian Republic, Russia – Latitude:
61°46'59"; Longitude: 34°19'59").
Schematic of experimental setup to record hysteresis loops under applied stresses is shown in Fig. 1.
Magnetometer contains the external coil which generates the magnetic field and internal receiving
coils. The specimen under test is placed in one of two receiving coils connected in series and
electrically in opposition. Signal from the receiver coils is integrated with the use of an active
integrator. The upper end of the tape is fixed on the stand, and the bottom one is loaded by hanging a
certain weight.
Figure 1. Installation for the measurement setup.
3. Results and discussion
1 mm wide and 30 µm thick Fe80-xCoxP14B6 ribbons were subjected to mechanical stresses. We
neglected the change of ribbon’s cross-section under load and calculated mechanical stress σ dividing
applied force by cross-sectional area of the ribbon.
Series of hysteresis loops under different linear mechanical loads applied along ribbons is shown in
Figs. 2 a,b. They illustrate experimental data for glass composition Fe45Co35P14B6 at magnetizing field
up to Hmax = 450 A/m and for Fe55Co25P14B6 metallic glass at H max = 2200 A/m. Two insets for graphs
show that saturation induction Bs increases with a load growth in both cases. It is notable that at low
loads the dependences Bs(σ) have a linear region to approximately σ = 100 MPa and then saturate with
Bs remaining almost constant. At the same time, coercive field Hc slightly increases under strain
deformation for both samples.
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IOP Conf. Series: Journal of Physics: Conf. Series 929 (2017) 012049 doi :10.1088/1742-6596/929/1/012049
Figure 2. a - Series of hysteresis loops for Fe45Co35P14B6 ribbon at magnetizing field up to Hmax = 450
A/m for different linear mechanical loads. b - Hysteresis loops for Fe55Co25P14B6 ribbon at Hmax = 2200
A/m.
Besides the increase of saturation magnetization Bs, growth of mechanical load results in changing
the shape of hysteresis loop. Loop squareness Bs/Brem is a useful parameter to quantify the change of
magnetic properties. Here Brem is a remnant induction remaining at H = 0. Fig. 3 depicts a series of
hysteresis loops for Fe48Co32P14B6 metallic glass. Inset to Fig. 3 presents loop’s squareness and
saturation induction Bs as functions of mechanical load. In contrast to Bs(σ), there is a small initial
region where the squareness seems to be independent on the load.
Figure 3. Series of hysteresis loops for Fe48Co32P14B6 metallic glass at magnetizing field up to Hmax =
300 A/m with different mechanical loads applied along the ribbon. Inset shows the dependences of
hysteresis loop’s squareness and saturation induction Bs on mechanical stress σ.
Under applied linear stress of 346.3 MPa, the saturation induction Bs increases from 1.24 to 1.7 T,
loop’s squareness also increases from 0.55 to 0.9, whereas the coercive field remains practically
unchanged. 3D plot in Fig. 4 summarizes both dependencies of magnetic induction B in Fe48Co32P14B6
glass on magnetic field H and applied linear stress σ.
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Figure 4. 3D plot for the field and stress dependent magnetic induction B(H,σ).
We found that magnetic response in magnetosoft rapidly quenched Fe80-xCoxP14B6 ribbons depends
also on the type of applied mechanical stress. Twisting deformations result in dramatic increase of
coercive field. Fig. 5 demonstrates this effect as a series of hysteresis loops for Fe48Co32P14B6 metallic
glass ribbons subjected to a torsional stress.
Figure 5. Series of hysteresis loops in Fe48Co32P14B6 ribbon magnetized up to Hmax = 400 A/m and
twisted at different angles.
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As clearly seen in Fig. 5, opposite to longitudinal strain the torsion deformations as high as 20.6 °/cm
result in huge growth of coercive field Hc from 27.5 A/m up to 60 A/m and significant increase of
squareness from 0.29 to 0.85, whereas the saturation induction Bs being practically unchanged.
4. Conclusions
Presented results show that different mechanical stresses have significant influence on the shape of
hysteresis loops in metallic glasses Fe80-xCoxP14B6. Magnetoelastic effect manifests itself by growth of
coercive field Hc, saturation induction Bs and loop’s squareness under applied longitudinal mechanical
load. Under twisting, on the contrary, saturation magnetization remains constant whereas both
coercive field Hc and loop’s squareness experience a rapid increase. These observations testify
possibility to discriminate different types of mechanical deformations and to build a multicomponent
strain gauge based on magnetosoft Fe80-xCoxP14B6 metallic glasses.
References
[1] Hollmark M, Tkatch VI, Grishin AM and Khartsev SI, 2001 Processing and Properties of Soft
Magnetic Fe40Co40P14B6 Amorphous Alloy IEE Transactions on Magnetics 37, 2278 – 2280.
[2] Tkatch VI, Grishin AM and Khartsev SI, 2002 Delayed nucleation in Fe40Co40P14B6 metallic glass
Materials Science and Engineering A337, 187 – 193.
[3] Prahova DA, Grishin AM, Ignahin VS, Lugovskaya LA, Osaulenko RN, 2016 Melt-spun Fe-Co-P-
B metglasses: structure, crystallization kinetics, magnetic properties Journal of Physics: Conference
Series, 769, 012034.
[4] Lugovskaya LA, Osaulenko RN, Grishin AM, Ignahin VS, 2015 X-ray study of soft magnetic
metallic glasses FeCoPB Proceedings of the Kola Science Centre, Chemistry and Materials, Special
Issue, 5 (31), 395-399.
