- Email: [email protected]
The role of residual stresses in magnetostrictive metallic glasses
Journal of Magnetism and Magnetic Materials WI-144 (1995) 267-268
The role of residual stressesin magnetostrictive metallic glasses L.M. Malkiiiski * Institute of Physics of Polish Academy of Sciences, Al. Lotnitiw 32/46, 02-668 Warszawa, Poland
Abstract Magnetoelastic properties of 11 compositions of the Fe-S&B metallic glasses have been measured. The A&effect, magnetomechanical coupling and magnetomechanical damping in the as-casted alloys showed large differences between the compositions and between different samples of the same composition. This was due to residual stresses. The improvement of the homogeneity of the magnetoelastic properties after stress-releasing treatments is discussed.
The Fe-Si-B metallic glasses are magnetostrictive materials with saturation magnetostriction between 29 X lo-’ and 39 X 10m6. The magnetoelastic properties, such as the ALeffect, magnetomechanical coupling and magnetomechanical damping have been measured for 11 compositions of the Fe-Si-B metallic glasses with Fe content ranging from 72 to 80%. Sets of 10 to 30 samples of each composition were taken for the measurements. The motional impedance circles method [I], was 2sed to measure ihe piezomagnetic properties of the alloys. Residual stresses in metallic glasses are produced during the rapid quenching of the alloy from the melt. Because of the extremely high cooling rates (above lo6 K/s) of the casting this process cannot be fully controlled. As was pointed out in some former papers [2-101, residual stresses in metallic glasses may play an important role in magnetization processes. They can influence magnetic and magnetoelastic properties of the magnetostrictive alloys via magnetomechanical coupling. The magnetoelastic energy depends on the stress and on the magnetostriction. The magnetostriction coefficients of several compositions of the alloys have been measured with the three-terminal capacitive method, the others were taken from the literature data. The experiments shu;‘;ed that the shapes of the dependence of Young’s modulus on magnetic field differed for the samples cut from single metallic glass ribbon [7]. Further measurements of the Fe-Si-B metallic glasses of different compositions proved that the inhomogeneity of the magneloelastic properties within a single ribbon is a general feature of the as-quenched magnetostrictive metallic glasses. The direct observation of the residual stresses in metallic glasses is difficult because of their amorphous structure, so the
* Corresponding author. [email protected].
Fax:
+ 48-22-430926;
email:
level of the residual stresses can be evaluated by the magnetic methods [2,4,9,IO]. The slresses in the asquenched alloys were estimated to be 5-30 MPa. The results of the measurements of the maximum and minimum values of some piezomagnetic parameters are collected in Table 1. It is clear from the table that it is possible to find samples with good and worse piezomagnetic parameters within each of the compositions. The average values of the parameters diiered between the compositions and the A&effect was above 0.2 for the and Fea,,Si,,Bw alloys, and it Fq8Si9B13, Fe,,Si,oBlz was below 0.1 in the Fe,$i,,B,,, Fe,sSi,B,,, Fe,Si,B,, and Fe,Si,B,z alloys. The residual stresses can be partly released by the annealing treatments at sufficiently high temperatures. This improves the homogeneity of the materials from the point of view of magnetoelastic properties. Additionally, it is possible to increase the magnetomechanical coupling by proper annealing treatments, such as annealing at temperatures above the Curie point or transverse field annealing below the Curie temperature+ Annealing above the Curie !emperature increases the A&effect and the magnetomechanical coupling coefficient several times, which can be seen in Table 2. Simultaneously, the spread of the results of the piezomagnetic parametea was considerably smalfer. In spite of a good reproducibility of the Young’s modulus curves versus magnetic biasing field within one composition, there were differences in the shapes of the curves for different compositions [IO]. An excellent reproducibility of the measurements of the magnetomechanical parameters can be achieved by annealing in the presence of a magnetic field oriented transversally to the ribbon length [6]. The shapes of the curves of AL-effect we:e in agreement with the theoretical predictions for sucl kind ul” &i;li;ii&~~S [II!. T+ internal StresS parameter after transverse magnetic field annealing was estimated to Se OS-.2 MPa 191, so it was reduced about
0304-8853/95/$09.50 8 1995 Elsevier Science B.V. All rights reserved SSDI 0304.8853(94)01341-1
268
L.M. Malkiiiski/Jaurnal
of Magnetism and Magnetic Materials 140-144 f’l99S) 267-268
Table 1 Maximum and minimum values of AE-effect, magne!omechanical coupling coefficient k and internal friction coefficient Q-t Fe-%-B metallic glasses Composition
k max (%I
A&n;,
KY FG%J%o
(%I
QA
QA
k
(lo-31
(10-3)
13.2
10.8 8.3
4.0 3.2
Fe75%5~10
19.5 5.5
8.9 4.0
23.3 19.0
F%Wh b&.B,~
18.3 14.9
7.5 3.6
21.7
21.2
10.0 13.6 13.5
Fe7aSi,B,,
30.8 30.1 18.7 6.4 28.4 28.5 35.0
21.4 9.4 12.1 3.7 7.3 3.2 18.6
33.1 31.8 25.2 16.4 34.1 20.2 33.0
11.2 16.2 17.1 10.7 13.3 10.8 19.3
bC%B~2 Fe79%2B9
Fe&&B,, %&B~~
Fe,Si,B,r FedloBlc
Table 2 Comparison between the averagc values of AE-effect and magnetomcchanical coupling coefficient k in as-quenched (with subscript ‘no’1 and in annealed (subscript ‘Ir’) Fe-Si-Et metailic glasses. The standard deviation is a measure of the homogeneity of the piezomagnetic parameters within selected composition of the alloy Composition
A E,.._(%)
A E,. (%)
k.,..” (%I
b&4h FW4Ao
14.0 f 4.0* ll.Sf 9.6* 21.4* 5.6* 17.65 9.9 f 25.0*
50.4 f 4.5 40.2 f 2.0 59.8 f 1.4 63.3i 3.5 73.2* I.5 49.0 +c2.0 62.0 i 2.0 65.0 f 1.5 61.2 f 2.5
18.7 f 11.0 $ 17.6 f I7.4f 24.8* 13.6 f 23.8 i 15.3 f 28.8 f
Fed%B~~ Fedidhi ~~dM%~ Fet,&4B,,
Fe,Si$,, Fe,Si,Bt, b&&~
3.6 1.0 3.3 3.6 5.8 0.9 6.9 4.4 5.3
k,.. (%) 3.3 2.0 2.4 2.3 4.6 2.3 6.5 3.0 3.6
52.6 * 42.0 * 57.2 f 58.7f 71.1 f 48.4 f 63.0 k 66.5 * 58.9 *
4.5 2.0 1.0 2.5 1.7 2.0 2.0 2.0 3.0
with the as-quenched state. The highest values of the A&effect achieved in the selected Fe-Si-B metallic glasses after transverse field Table 3 The best results of the measurements of the AE-effect and magne. tomechanical coupling k after transverse field annealing and corres sponding anneuling temperatures (T,,,) and times (r,,,). The compositions marked by ’ were preliminarily annealed at 425°C for 15 min. ti,,,,, denotes the biasing field strength for which thr AEeeffect has its
maximum AE/E,
k
(lo)
(%I
62.4 53.5 71.4 70.2 74.9 74.3 63.8 77.2 78.2
64.5 51.5 70.3 67.3 68.9 70.2 64.8 66.5 73.4
h (h)
158 158 163 173 177 196 222 215 213
360 370 360 330 350 370 330 350 350
4 4 4 4 4 8 4 8 8
17.7 13.6 17.5 9.5 23.6 10.9 17.3
4.1 5.0 11.2 7.1 6.7 3.2 5.7 3.3 6.3
annealing are presented in Table 3. They depend on the magnetostriction and the induced anisotropy, which is in correlation with the II,,,,,. Magnetomechanical coupling of about 0.7 can easily be achieved in the alloys by this kind of treatment. The exception was the Fe,5Si,5B,, alloy, where the magnetostatic interactions limited improvement of the magnetoelastic properties because of a very rough surface of the alIoy samples. On the other hand the best results have been obtained in the Fe,Si,,B,, alloy with a perfect surface.
References
one order of magnitude in comparison
Composition
7.6 8.2
in different
-
[l] CM. van der Burg& Philips Res. Rep. 8 (1953) 91. [2] Z. Kaczkowski and L. Matkiiiski, J. Magn. Magn. Mater. 41 (1984) 343. [3] Z. Kaczkowski and L. Malkitiski, Acta Physica Polon. A 68 (1985) 335. [4] B.S. Berry, Metallic Glasses (Amer. Sot. for Metals, Metals Park, OH, 1978) p. 161.
[5] Z. Kaczkowski
and L. Malkibski,
Key Engin. Materials
40-41 (1990) 385. [6] Z. Kaczkowski
and L. MaIkiiiski, J. Magn. Magn. Mater. 83 (1990) 365. [7] L. MabchWci, Z. Kaczkowski and B. Augustyniak, Physics of Magnetic Materials V, eds. W. Corzkowski, M. Gutowski, ELK. tachowicz and H. Szymczak (World Scientific, Singapore, 1990) 387. [8] L. MaWski, S. Kiss, L,F. Kiss and Z. VCrtesy, Electron Technology (Institute of Electron Technology, Warsaw) 23, l/4 (1990) 101. [9] L. MaIkiBski, Z. Kaczkowski and B. Augustyniak, J. Magn. Magn. Mater. 112 (1992) 323. [lo] L. Malkihski and B. Augustyniak, Mater, Sci. Forum lf9121 (1993) 585. 1111 P.T. Squire, J. Megn. Magn. Mater, 87 (1990) 299.
The role of residual stressesin magnetostrictive metallic glasses L.M. Malkiiiski * Institute of Physics of Polish Academy of Sciences, Al. Lotnitiw 32/46, 02-668 Warszawa, Poland
Abstract Magnetoelastic properties of 11 compositions of the Fe-S&B metallic glasses have been measured. The A&effect, magnetomechanical coupling and magnetomechanical damping in the as-casted alloys showed large differences between the compositions and between different samples of the same composition. This was due to residual stresses. The improvement of the homogeneity of the magnetoelastic properties after stress-releasing treatments is discussed.
The Fe-Si-B metallic glasses are magnetostrictive materials with saturation magnetostriction between 29 X lo-’ and 39 X 10m6. The magnetoelastic properties, such as the ALeffect, magnetomechanical coupling and magnetomechanical damping have been measured for 11 compositions of the Fe-Si-B metallic glasses with Fe content ranging from 72 to 80%. Sets of 10 to 30 samples of each composition were taken for the measurements. The motional impedance circles method [I], was 2sed to measure ihe piezomagnetic properties of the alloys. Residual stresses in metallic glasses are produced during the rapid quenching of the alloy from the melt. Because of the extremely high cooling rates (above lo6 K/s) of the casting this process cannot be fully controlled. As was pointed out in some former papers [2-101, residual stresses in metallic glasses may play an important role in magnetization processes. They can influence magnetic and magnetoelastic properties of the magnetostrictive alloys via magnetomechanical coupling. The magnetoelastic energy depends on the stress and on the magnetostriction. The magnetostriction coefficients of several compositions of the alloys have been measured with the three-terminal capacitive method, the others were taken from the literature data. The experiments shu;‘;ed that the shapes of the dependence of Young’s modulus on magnetic field differed for the samples cut from single metallic glass ribbon [7]. Further measurements of the Fe-Si-B metallic glasses of different compositions proved that the inhomogeneity of the magneloelastic properties within a single ribbon is a general feature of the as-quenched magnetostrictive metallic glasses. The direct observation of the residual stresses in metallic glasses is difficult because of their amorphous structure, so the
* Corresponding author. [email protected].
Fax:
+ 48-22-430926;
email:
level of the residual stresses can be evaluated by the magnetic methods [2,4,9,IO]. The slresses in the asquenched alloys were estimated to be 5-30 MPa. The results of the measurements of the maximum and minimum values of some piezomagnetic parameters are collected in Table 1. It is clear from the table that it is possible to find samples with good and worse piezomagnetic parameters within each of the compositions. The average values of the parameters diiered between the compositions and the A&effect was above 0.2 for the and Fea,,Si,,Bw alloys, and it Fq8Si9B13, Fe,,Si,oBlz was below 0.1 in the Fe,$i,,B,,, Fe,sSi,B,,, Fe,Si,B,, and Fe,Si,B,z alloys. The residual stresses can be partly released by the annealing treatments at sufficiently high temperatures. This improves the homogeneity of the materials from the point of view of magnetoelastic properties. Additionally, it is possible to increase the magnetomechanical coupling by proper annealing treatments, such as annealing at temperatures above the Curie point or transverse field annealing below the Curie temperature+ Annealing above the Curie !emperature increases the A&effect and the magnetomechanical coupling coefficient several times, which can be seen in Table 2. Simultaneously, the spread of the results of the piezomagnetic parametea was considerably smalfer. In spite of a good reproducibility of the Young’s modulus curves versus magnetic biasing field within one composition, there were differences in the shapes of the curves for different compositions [IO]. An excellent reproducibility of the measurements of the magnetomechanical parameters can be achieved by annealing in the presence of a magnetic field oriented transversally to the ribbon length [6]. The shapes of the curves of AL-effect we:e in agreement with the theoretical predictions for sucl kind ul” &i;li;ii&~~S [II!. T+ internal StresS parameter after transverse magnetic field annealing was estimated to Se OS-.2 MPa 191, so it was reduced about
0304-8853/95/$09.50 8 1995 Elsevier Science B.V. All rights reserved SSDI 0304.8853(94)01341-1
268
L.M. Malkiiiski/Jaurnal
of Magnetism and Magnetic Materials 140-144 f’l99S) 267-268
Table 1 Maximum and minimum values of AE-effect, magne!omechanical coupling coefficient k and internal friction coefficient Q-t Fe-%-B metallic glasses Composition
k max (%I
A&n;,
KY FG%J%o
(%I
QA
QA
k
(lo-31
(10-3)
13.2
10.8 8.3
4.0 3.2
Fe75%5~10
19.5 5.5
8.9 4.0
23.3 19.0
F%Wh b&.B,~
18.3 14.9
7.5 3.6
21.7
21.2
10.0 13.6 13.5
Fe7aSi,B,,
30.8 30.1 18.7 6.4 28.4 28.5 35.0
21.4 9.4 12.1 3.7 7.3 3.2 18.6
33.1 31.8 25.2 16.4 34.1 20.2 33.0
11.2 16.2 17.1 10.7 13.3 10.8 19.3
bC%B~2 Fe79%2B9
Fe&&B,, %&B~~
Fe,Si,B,r FedloBlc
Table 2 Comparison between the averagc values of AE-effect and magnetomcchanical coupling coefficient k in as-quenched (with subscript ‘no’1 and in annealed (subscript ‘Ir’) Fe-Si-Et metailic glasses. The standard deviation is a measure of the homogeneity of the piezomagnetic parameters within selected composition of the alloy Composition
A E,.._(%)
A E,. (%)
k.,..” (%I
b&4h FW4Ao
14.0 f 4.0* ll.Sf 9.6* 21.4* 5.6* 17.65 9.9 f 25.0*
50.4 f 4.5 40.2 f 2.0 59.8 f 1.4 63.3i 3.5 73.2* I.5 49.0 +c2.0 62.0 i 2.0 65.0 f 1.5 61.2 f 2.5
18.7 f 11.0 $ 17.6 f I7.4f 24.8* 13.6 f 23.8 i 15.3 f 28.8 f
Fed%B~~ Fedidhi ~~dM%~ Fet,&4B,,
Fe,Si$,, Fe,Si,Bt, b&&~
3.6 1.0 3.3 3.6 5.8 0.9 6.9 4.4 5.3
k,.. (%) 3.3 2.0 2.4 2.3 4.6 2.3 6.5 3.0 3.6
52.6 * 42.0 * 57.2 f 58.7f 71.1 f 48.4 f 63.0 k 66.5 * 58.9 *
4.5 2.0 1.0 2.5 1.7 2.0 2.0 2.0 3.0
with the as-quenched state. The highest values of the A&effect achieved in the selected Fe-Si-B metallic glasses after transverse field Table 3 The best results of the measurements of the AE-effect and magne. tomechanical coupling k after transverse field annealing and corres sponding anneuling temperatures (T,,,) and times (r,,,). The compositions marked by ’ were preliminarily annealed at 425°C for 15 min. ti,,,,, denotes the biasing field strength for which thr AEeeffect has its
maximum AE/E,
k
(lo)
(%I
62.4 53.5 71.4 70.2 74.9 74.3 63.8 77.2 78.2
64.5 51.5 70.3 67.3 68.9 70.2 64.8 66.5 73.4
h (h)
158 158 163 173 177 196 222 215 213
360 370 360 330 350 370 330 350 350
4 4 4 4 4 8 4 8 8
17.7 13.6 17.5 9.5 23.6 10.9 17.3
4.1 5.0 11.2 7.1 6.7 3.2 5.7 3.3 6.3
annealing are presented in Table 3. They depend on the magnetostriction and the induced anisotropy, which is in correlation with the II,,,,,. Magnetomechanical coupling of about 0.7 can easily be achieved in the alloys by this kind of treatment. The exception was the Fe,5Si,5B,, alloy, where the magnetostatic interactions limited improvement of the magnetoelastic properties because of a very rough surface of the alIoy samples. On the other hand the best results have been obtained in the Fe,Si,,B,, alloy with a perfect surface.
References
one order of magnitude in comparison
Composition
7.6 8.2
in different
-
[l] CM. van der Burg& Philips Res. Rep. 8 (1953) 91. [2] Z. Kaczkowski and L. Matkiiiski, J. Magn. Magn. Mater. 41 (1984) 343. [3] Z. Kaczkowski and L. Malkitiski, Acta Physica Polon. A 68 (1985) 335. [4] B.S. Berry, Metallic Glasses (Amer. Sot. for Metals, Metals Park, OH, 1978) p. 161.
[5] Z. Kaczkowski
and L. Malkibski,
Key Engin. Materials
40-41 (1990) 385. [6] Z. Kaczkowski
and L. MaIkiiiski, J. Magn. Magn. Mater. 83 (1990) 365. [7] L. MabchWci, Z. Kaczkowski and B. Augustyniak, Physics of Magnetic Materials V, eds. W. Corzkowski, M. Gutowski, ELK. tachowicz and H. Szymczak (World Scientific, Singapore, 1990) 387. [8] L. MaWski, S. Kiss, L,F. Kiss and Z. VCrtesy, Electron Technology (Institute of Electron Technology, Warsaw) 23, l/4 (1990) 101. [9] L. MaIkiBski, Z. Kaczkowski and B. Augustyniak, J. Magn. Magn. Mater. 112 (1992) 323. [lo] L. Malkihski and B. Augustyniak, Mater, Sci. Forum lf9121 (1993) 585. 1111 P.T. Squire, J. Megn. Magn. Mater, 87 (1990) 299.