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Texture and magnetic properties of double-roller meltspun Fe6.5 wt%Si ribbons
Journal of Magnetism and Magnetic Materials 254–255 (2003) 29–31
Texture and magnetic properties of double-roller meltspun Fe6.5 wt%Si ribbons K. Moras, W. Riehemann* Institut fur . Werkstoffkunde und Werkstofftechnik der TU Clausthal, Agricolastrasse 6, D-38678 Clausthal-Zellerfeld, Germany
Abstract Texture and magnetic properties of double-roller meltspun FeSi6.5% ribbons were investigated. Thin ribbons show a strong {1 0 0}/0 v wS texture in the as-quenched state which develops to a {1 0 0}/1 3 0S texture after annealing at 12001C. The magnetic losses and the coercivity decrease by a factor of 2–3 due to annealing; they are somewhat higher compared to single-roller ribbons. r 2002 Elsevier Science B.V. All rights reserved. Keywords: FeSi6.5%; Rapid quenching; Melt spinning; Double roller; Texture; Magnetic loss
1. Introduction
2. Experimental
Rapidly quenched iron 6.5 wt% silicon (FeSi6.5) ribbons prepared by melt spinning or planar flow casting are interesting soft magnetic materials with low power losses due to their zero magnetostriction and high specific electrical resistance. However, the magnetic properties depend strongly on the texture and the thickness of the ribbons [1–3]. In former investigations of this material produced by a single-roller technique, a strong {1 0 0}/0 1 1S texture was found after annealing at 12001C under 8 Pa air pressure for 1 h. Unfortunately, the [1 0 0] pole of the single-roller ribbon crystallites was tilted to the surface normal into the spinning direction by an angle of about 181, which leads to a deterioration of the magnetic properties [2,3]. Similar results are reported by Cunha et al. [4]. Lower cooling rates as well as double-sided heat dissipation are expected to decrease this angle. Therefore, in the present work FeSi6.5 double-roller processed ribbons are investigated. The properties are compared to single-roller results reported in Refs. [1,2].
The ribbons have been cast with various surface velocities of the wheel resulting to thicknesses between 40and 90 mm and widths between 4 and 8 mm. The used double-roller facility [5] and the mechanical properties of the ribbons [6] were described in detail by Jurisch et al. The ribbons were investigated in the as-quenched state and after a heat treatment at 12001C for 90 min under 8 Pa residual pressure of air (without surface oxidation). A grain size of 10–30 mm in the as-quenched tapes and 50–200 mm after the heat treatment was typical.
*Corresponding author. Tel.: +49-5323-722603; fax: +495323-723148. E-mail address: [email protected] (W. Riehemann).
2.1. Texture analyses For the measurement of the ribbons pole figures and the calculation of textures (orientation distribution functions, ODF) a computer controlled X-ray diffractometer D5000 (Siemens) with Euler-cradle, linear translation table and Diffracplus Software (BrukerAXS) has been used. The (1 1 0), (2 0 0) and (2 1 1) pole figures were measured in reflection geometry with CoKa radiation. For the texture measurements samples of dimensions 8 mm 15 mm were cut out of the ribbons. For narrower ribbons two strips were mounted side by side to attain a sufficient area for the measurement. In the case of annealed coarse-grained samples it was very
0304-8853/03/$ - see front matter r 2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 4 - 8 8 5 3 ( 0 2 ) 0 0 7 4 0 - 0
30
K. Moras, W. Riehemann / Journal of Magnetism and Magnetic Materials 254–255 (2003) 29–31
difficult to obtain a sufficient grain statistics for the pole figure measurement. The statistics were improved by the following means: (a) a special divergence slit was used which makes a wide equatorial but small axial divergence of the primary radiation bundle and leads to an illuminated area on the sample surface of about 6 mm 0.8 mm at minimum Bragg angle y: (b) during the measurement, the sample oscillates around the mean position by an amplitude of 4 mm parallel to the longitudinal extent of the sample. (c) the pole figures have been averaged by up to 10 single measurements each one measured at a slightly different incidence angle (Dy ¼ 0:51) to increase the number of reflecting grains. 2.2. Magnetic measurements
0 10 20 30 40 50
3. Results and discussion
60 70 80 90
0
10 20 30 40 50 60 70 80 90
ϕ1/˚
(b)
4
3
Density
From the measured pole figures the ODF which fully describes the texture of the samples has been calculated. In Fig. 1 the results for the thinnest ribbon (d ¼ 44 mm) are shown. From the pole figure and the ODF cut a strong {1 0 0}/0 v wS fibre without any tilting against the surface normal is recognisable. The orientation density along j1 for F ¼ 01 shows weak maxima at 7261 against the longitudinal direction of the ribbon, that means {1 0 0}/3 1 0S components. The texture of the same sample after heat treatment was analysed using the technique of pole figure smoothing mentioned above. In Fig. 2 a somewhat ‘‘fissured’’ (2 0 0) pole figure can be seen but after the ODF calculation a stronger texture with orientation density of up to 4.5 for the components {1 0 0}/3 1 0S is visible. The [0 1 0] pole shows a 7201 deviation to the ribbon direction but no tilting of [1 0 0] against the surface normal. Additionally, a weak {0 1 4}/4 4 1S component was found. The thicker samples (60–90 mm) of the as-quenched ribbons show weak textures with maximum orientation densities in the range 1.5–1.8. After the heat treatment very sharp textures with a 5–201 or 60–651 tilting of the [1 0 0] pole against the surface normal and with 20–551 deviation of [0 1 0] to the ribbon direction were found. Table 1 shows the results of the measurements of the magnetic properties for several samples before (u) and after (g at sample name) the heat treatment at a
3.9 3.1 2.3
(a)
Φ
The AC power losses and the coercivity of the ribbons were measured for frequencies from 3.2 to 20 kHz and polarisations from 0.6 to 1.4 T using a computercontrolled AC digital hysteresis recorder. The apparatus is described in detail by Ramin et al. [7]. For the magnetic measurements samples 100 mm long and 3 mm wide were cut out of the ribbons.
2
1
0 0 (c)
10 20 30 40 50 60 70 80 90
ϕ1/˚
Fig. 1. Texture of sample J80asq (as quenched). (a) Pole figure (200), (b) ODF cut at j2 ¼ 01; (c) Fiber cut along j1 at j2¼ 01; F ¼ 01:
K. Moras, W. Riehemann / Journal of Magnetism and Magnetic Materials 254–255 (2003) 29–31
31
Table 1 Magnetic properties of FeSi6.5% samples
(a)
Si(wt%)
d(mm)
Ptot /(W/kg)
Hc (A/m)
J80asq J80ann J82asq J82ann J102asq J102ann
6.60
44
6.30
90
6.37
80
4.00 1.69 2.88 1.06 4.55 1.29
146 62 111 41 173 47
magnetisation frequency of f ¼ 50 Hz and a polarisation of J ¼ 1:0 T. An improvement of the magnetic properties, the energy loss as well as the dynamic coercivity, after the heat treatment by a factor of two–three is obtained. The reason for this is, in addition to the growth of grains and the reduction of internal stresses, in the case of thin ribbons in particular the sharpening of texture in a favourable way. In comparison with annealed singleroller ribbons the iron losses, the coercivity and the domain wall density are somewhat higher.
3.0 6.0 8.0
0 10 20 30
Φ
Sample
40 50
4. Conclusions
60 70 80 90 0
10 20 30 40 50 60 70 80 90
ϕ1/˚
(b)
Annealed thin (40 mm) double-roller meltspun FeSi6.5 ribbons show a {1 0 0}/1 3 0S texture without tilting of the [1 0 0] pole to the surface normal but with 7201 deviation of [0 1 0] pole to the ribbon direction. Thicker ribbons (90 mm) show a 5–201 or 60–651 tilting of the [1 0 0] pole against the surface normal with 20–551 deviation of [0 1 0] to the ribbon direction. The iron losses, the coercivity and the domain wall density were found to be somewhat higher as for single-roller ribbons.
4
References
Density
3 2 1 0 -0.5
0 (c)
10 20 30 40 50 60 70 80 90
ϕ1/˚
Fig. 2. Texture of sample J80ann (annealed). (a) Pole figure (200), (b) ODF cut at j2 ¼ 01; (c) Fiber cut along j1 at j2 ¼ 01; F ¼ 01:
[1] M.J. Tenwick, H.A. Davies, Int. J. Rapid Solidif. 1 (1985) 143. [2] M. Pott-Langemeier, W. Riehemann, W. Heye, Mat. Sci. Eng. A 133 (1991) 204. [3] M. Pott-Langemeier, W. Riehemann, Z. Metallkd. 84 (1993) 72. [4] M.A. Cunha, G.W. Johnson, J. Mater. Sci. 25 (1990) 2481. [5] M. Jurisch, H. Fiedler, R. Sellger, H. Zimmermann, in: Seminar on Rapid Solidification—Technology Material Properties—Application, Dresden, 1988, p. 90. [6] H. Seifert, M. Jurisch, J. Tobisch, C.-G. Oertel, Mat. Sci. Eng. A133 (1991) 292. [7] D. Ramin, W. Riehemann, Techn. Messen 68 (2001) 3.
Texture and magnetic properties of double-roller meltspun Fe6.5 wt%Si ribbons K. Moras, W. Riehemann* Institut fur . Werkstoffkunde und Werkstofftechnik der TU Clausthal, Agricolastrasse 6, D-38678 Clausthal-Zellerfeld, Germany
Abstract Texture and magnetic properties of double-roller meltspun FeSi6.5% ribbons were investigated. Thin ribbons show a strong {1 0 0}/0 v wS texture in the as-quenched state which develops to a {1 0 0}/1 3 0S texture after annealing at 12001C. The magnetic losses and the coercivity decrease by a factor of 2–3 due to annealing; they are somewhat higher compared to single-roller ribbons. r 2002 Elsevier Science B.V. All rights reserved. Keywords: FeSi6.5%; Rapid quenching; Melt spinning; Double roller; Texture; Magnetic loss
1. Introduction
2. Experimental
Rapidly quenched iron 6.5 wt% silicon (FeSi6.5) ribbons prepared by melt spinning or planar flow casting are interesting soft magnetic materials with low power losses due to their zero magnetostriction and high specific electrical resistance. However, the magnetic properties depend strongly on the texture and the thickness of the ribbons [1–3]. In former investigations of this material produced by a single-roller technique, a strong {1 0 0}/0 1 1S texture was found after annealing at 12001C under 8 Pa air pressure for 1 h. Unfortunately, the [1 0 0] pole of the single-roller ribbon crystallites was tilted to the surface normal into the spinning direction by an angle of about 181, which leads to a deterioration of the magnetic properties [2,3]. Similar results are reported by Cunha et al. [4]. Lower cooling rates as well as double-sided heat dissipation are expected to decrease this angle. Therefore, in the present work FeSi6.5 double-roller processed ribbons are investigated. The properties are compared to single-roller results reported in Refs. [1,2].
The ribbons have been cast with various surface velocities of the wheel resulting to thicknesses between 40and 90 mm and widths between 4 and 8 mm. The used double-roller facility [5] and the mechanical properties of the ribbons [6] were described in detail by Jurisch et al. The ribbons were investigated in the as-quenched state and after a heat treatment at 12001C for 90 min under 8 Pa residual pressure of air (without surface oxidation). A grain size of 10–30 mm in the as-quenched tapes and 50–200 mm after the heat treatment was typical.
*Corresponding author. Tel.: +49-5323-722603; fax: +495323-723148. E-mail address: [email protected] (W. Riehemann).
2.1. Texture analyses For the measurement of the ribbons pole figures and the calculation of textures (orientation distribution functions, ODF) a computer controlled X-ray diffractometer D5000 (Siemens) with Euler-cradle, linear translation table and Diffracplus Software (BrukerAXS) has been used. The (1 1 0), (2 0 0) and (2 1 1) pole figures were measured in reflection geometry with CoKa radiation. For the texture measurements samples of dimensions 8 mm 15 mm were cut out of the ribbons. For narrower ribbons two strips were mounted side by side to attain a sufficient area for the measurement. In the case of annealed coarse-grained samples it was very
0304-8853/03/$ - see front matter r 2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 0 4 - 8 8 5 3 ( 0 2 ) 0 0 7 4 0 - 0
30
K. Moras, W. Riehemann / Journal of Magnetism and Magnetic Materials 254–255 (2003) 29–31
difficult to obtain a sufficient grain statistics for the pole figure measurement. The statistics were improved by the following means: (a) a special divergence slit was used which makes a wide equatorial but small axial divergence of the primary radiation bundle and leads to an illuminated area on the sample surface of about 6 mm 0.8 mm at minimum Bragg angle y: (b) during the measurement, the sample oscillates around the mean position by an amplitude of 4 mm parallel to the longitudinal extent of the sample. (c) the pole figures have been averaged by up to 10 single measurements each one measured at a slightly different incidence angle (Dy ¼ 0:51) to increase the number of reflecting grains. 2.2. Magnetic measurements
0 10 20 30 40 50
3. Results and discussion
60 70 80 90
0
10 20 30 40 50 60 70 80 90
ϕ1/˚
(b)
4
3
Density
From the measured pole figures the ODF which fully describes the texture of the samples has been calculated. In Fig. 1 the results for the thinnest ribbon (d ¼ 44 mm) are shown. From the pole figure and the ODF cut a strong {1 0 0}/0 v wS fibre without any tilting against the surface normal is recognisable. The orientation density along j1 for F ¼ 01 shows weak maxima at 7261 against the longitudinal direction of the ribbon, that means {1 0 0}/3 1 0S components. The texture of the same sample after heat treatment was analysed using the technique of pole figure smoothing mentioned above. In Fig. 2 a somewhat ‘‘fissured’’ (2 0 0) pole figure can be seen but after the ODF calculation a stronger texture with orientation density of up to 4.5 for the components {1 0 0}/3 1 0S is visible. The [0 1 0] pole shows a 7201 deviation to the ribbon direction but no tilting of [1 0 0] against the surface normal. Additionally, a weak {0 1 4}/4 4 1S component was found. The thicker samples (60–90 mm) of the as-quenched ribbons show weak textures with maximum orientation densities in the range 1.5–1.8. After the heat treatment very sharp textures with a 5–201 or 60–651 tilting of the [1 0 0] pole against the surface normal and with 20–551 deviation of [0 1 0] to the ribbon direction were found. Table 1 shows the results of the measurements of the magnetic properties for several samples before (u) and after (g at sample name) the heat treatment at a
3.9 3.1 2.3
(a)
Φ
The AC power losses and the coercivity of the ribbons were measured for frequencies from 3.2 to 20 kHz and polarisations from 0.6 to 1.4 T using a computercontrolled AC digital hysteresis recorder. The apparatus is described in detail by Ramin et al. [7]. For the magnetic measurements samples 100 mm long and 3 mm wide were cut out of the ribbons.
2
1
0 0 (c)
10 20 30 40 50 60 70 80 90
ϕ1/˚
Fig. 1. Texture of sample J80asq (as quenched). (a) Pole figure (200), (b) ODF cut at j2 ¼ 01; (c) Fiber cut along j1 at j2¼ 01; F ¼ 01:
K. Moras, W. Riehemann / Journal of Magnetism and Magnetic Materials 254–255 (2003) 29–31
31
Table 1 Magnetic properties of FeSi6.5% samples
(a)
Si(wt%)
d(mm)
Ptot /(W/kg)
Hc (A/m)
J80asq J80ann J82asq J82ann J102asq J102ann
6.60
44
6.30
90
6.37
80
4.00 1.69 2.88 1.06 4.55 1.29
146 62 111 41 173 47
magnetisation frequency of f ¼ 50 Hz and a polarisation of J ¼ 1:0 T. An improvement of the magnetic properties, the energy loss as well as the dynamic coercivity, after the heat treatment by a factor of two–three is obtained. The reason for this is, in addition to the growth of grains and the reduction of internal stresses, in the case of thin ribbons in particular the sharpening of texture in a favourable way. In comparison with annealed singleroller ribbons the iron losses, the coercivity and the domain wall density are somewhat higher.
3.0 6.0 8.0
0 10 20 30
Φ
Sample
40 50
4. Conclusions
60 70 80 90 0
10 20 30 40 50 60 70 80 90
ϕ1/˚
(b)
Annealed thin (40 mm) double-roller meltspun FeSi6.5 ribbons show a {1 0 0}/1 3 0S texture without tilting of the [1 0 0] pole to the surface normal but with 7201 deviation of [0 1 0] pole to the ribbon direction. Thicker ribbons (90 mm) show a 5–201 or 60–651 tilting of the [1 0 0] pole against the surface normal with 20–551 deviation of [0 1 0] to the ribbon direction. The iron losses, the coercivity and the domain wall density were found to be somewhat higher as for single-roller ribbons.
4
References
Density
3 2 1 0 -0.5
0 (c)
10 20 30 40 50 60 70 80 90
ϕ1/˚
Fig. 2. Texture of sample J80ann (annealed). (a) Pole figure (200), (b) ODF cut at j2 ¼ 01; (c) Fiber cut along j1 at j2 ¼ 01; F ¼ 01:
[1] M.J. Tenwick, H.A. Davies, Int. J. Rapid Solidif. 1 (1985) 143. [2] M. Pott-Langemeier, W. Riehemann, W. Heye, Mat. Sci. Eng. A 133 (1991) 204. [3] M. Pott-Langemeier, W. Riehemann, Z. Metallkd. 84 (1993) 72. [4] M.A. Cunha, G.W. Johnson, J. Mater. Sci. 25 (1990) 2481. [5] M. Jurisch, H. Fiedler, R. Sellger, H. Zimmermann, in: Seminar on Rapid Solidification—Technology Material Properties—Application, Dresden, 1988, p. 90. [6] H. Seifert, M. Jurisch, J. Tobisch, C.-G. Oertel, Mat. Sci. Eng. A133 (1991) 292. [7] D. Ramin, W. Riehemann, Techn. Messen 68 (2001) 3.