Effects of Magnetic Field Strength on Microstructure
and Texture Evolution in Cold-Rolled Pure Copper by
Magnetic Field Annealing
T He, X Zhao, G.J. Zhang
To cite this version:
T He, X Zhao, G.J. Zhang. Effects of Magnetic Field Strength on Microstructure and Texture Evolution in Cold-Rolled Pure Copper by Magnetic Field Annealing. 8th International
Conference on Electromagnetic Processing of Materials, Oct 2015, Cannes, France. EPM2015.
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Effects of Magnetic Field Strength on Microstructure and Texture Evolution in Cold-Rolled
Pure Copper by Magnetic Field Annealing
T. He1, G. J. Zhang2, X. Zhao2
1
2
Research Institute, Northeastern University, Shenyang, 110189, China
Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang,
110189, China
Corresponding author: zhaox@mail.neu.edu.cn
Abstract
Effects of magnetic field strength on the evolution of recrystallization microstructure and texture in cold-rolled pure
copper are investigated after annealing at 300℃ in a magnetic field up to 12 T. The average intensity of Cube texture of
the annealing specimens with the field is higher than that without the field (0T). As the strength of field increases, the
intensity of Cube texture strengthened to a maximum value at 8T, and then slightly decreased. The results may be
attributed to boundary migration induced by the magnetic field during grain growth process.
Key words: Magnetic field strength, Texture, Recrystallization, Pure copper
Introduction
There is a nice bit of experimental evidence that the microstructure and texture evolution during heat treatment
subsequence to plastic deformation in metallic materials can be affected by an external high magnetic field [1, 2]. Most
researches in this field are related to magnetically affected recrystallization in ferromagnetic materials [3, 4]. By the
development of high magnetic field technologies, the effect of a high magnetic field on metallurgical phenomena in
non-ferromagnetic materials has been hot researching issues. The results as shown in the past by Molodov [5-7] for Zn,
Ti and Al polycrystalline can reveal that the recrystallized microstructure and texture can be affected by the external
high magnetic field. Their experiments were carried out at various annealing temperatures for various holding time at
each temperature with fixed strength of magnetic field when the field was applied. However, some other investigations
[8-10] suggested that there may be some interesting effect at certain field strengths. On the basis of this argument, the
present work studied the effect of magnetic field strength on the evolution of recrystallization microstructure and texture
in a cold-rolled pure copper during annealing and reported some new experimental findings.
Experimental
The material used is 98% cold-rolled pure copper of 0.1mm in thickness, with the following chemical composition (wt
pct): Fe 0.01; Pb 0.08; Cu 99.9. The dimension of the specimens is 20mm×10mm×0.1mm. The specimens are annealed
at 300℃ for 30min with a heating rate of 5℃/min and then cooled in water. For magnetic field annealing, a magnetic
field from 4 T up to 12 T (with 2T intervals from 4 T to 12 T) is applied during the isothermal holding process. The
specimens are kept in the zero magnetic area with their rolling direction (RD) parallel to the magnetic field direction
(MD). For comparison, the non-field annealing is carried out in the same furnace under the same heat treatment
conditions.
The global textures are obtained from the 1/4 layer of specimen thickness by measuring three incomplete {111}, {200}
and {220} pole figures, using the Schulz back-reflection method, with Cu Kα radiation. The corresponding ODFs are
calculated with LabTex 3.0 software. Microstructures of longitudinal sections of the specimens are observed by
orientation imaging microscopy (OIM). The scan is carried out over the area of 613×459 measuring points with a 0.5
μm step size, and the corresponding ODFs are computed using the Channel 5 software.
Results and Discussion
Fig. 1 shows the constant φ2 ODF sections of the as-rolled specimen which is characterized by three major ODF peaks,
spread around the orientations {112}<111> (Cu-), {123}<634> (S-), and {011}<211> (Brass-component), together
making up so called β-fibre. Fig. 2 compares the constant φ2=45° ODF sections of specimens annealed at 300℃ with
different strength of magnetic field. The Cube texture component occurred in all annealing specimens with and without
the field (0T). The orientation distributions of the fully recrystallized samples are very similar for both the specimens
without the field (0T) and with the field despite the different strength of field. The observed variation in the orientation
intensity of Cube texture for all the annealed specimens are shown in Fig.3. It is obvious that the orientation intensity of
Cube texture for the annealing specimens with the field is higher than that without field (0T). The orientation intensity
of Cube texture increases with the increasing of magnetic field strength. Their intensities are up to a maximum at 8T
and then slightly decrease. This indicates that magnetic field annealing promote the growth of the recrystallized grains
with Cube orientation. This promotion effect increases with the field strength increase, especially when the field is 8 T,
where the result is more pronounced. Fig.4 shows the variation of volume fraction for Cube texture component with
magnetic field strength. With the increasing of the magnetic field strength, the volume fraction of the Cube texture
component increases firstly and then slightly decreases. The maximum value occurred when the field is 8 T.
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
Fig. 2: Constant φ2=45° ODF sections of annealing specimens
with different strength of magnetic field. (a) 0T, (b) 4T, (c)6T,
(d) 8T, (e) 10T, (f) 12T.
0T
4T
6T
8T
10T
12T
0
10
64
Volume Fraction (%)
Orientation Intensity f(g)
Fig. 1: Constant φ2 ODF sections of
cold-rolled pure copper.
20
30
40
500
PHI 1 ( )
60
70
80
62
60
58
56
54
0T
90
4T
6T
8T
10T
12T
Magnetic Field (T)
Fig. 3: Variation of Cube orientation intensity with
magnetic field strength of annealed specimens.
Fig. 4: Variation of volume fraction of cube component
with magnetic field strength of annealed specimens.
Fig. 5 shows the microstructures of longitudinal sections of the specimens annealed at 300℃ for 30min with different
magnetic field strength. In these OIM maps, both the rolling direction and the magnetic field direction are horizontal.
There are some grains with different size and shape in the figures instead of deformed structures. This indicated that the
recrystallization is essentially complete and grain growth is starting for all the annealed specimens. Most of the big
grains in the figures with the same or similar color (red color) are Cube orientation. This indicated that magnetic field
promoted the selective growth of the grains with Cube orientation. The quantitative comparison of their recrystallized
grain size with magnetic field strength is shown in Fig. 6. The recrystallized grain size in the Fig. 6 counts by their
diameter. From the figure one can see that the size of recrystallized grains increases firstly and then decreases slightly
with the increase of the magnetic field strength. The peak value still corresponds to the 8 T field. This result once again
confirms that the magnetic field promotes the selective growth of recrystallized grains with Cube orientation during
annealing.
So far, the effect of high magnetic field and their influence on the recrystallization process and texture evolution is not
well understood. As pointed elsewhere [11-13], one of the mechanisms which can be responsible for the magnetically
related effects during grain growth and recrystallization in dia- and paramagnetic materials is boundary migration
induced by the differences in magnetic free energy. The magnetic force acting on the boundary of two crystals that have
different magnetic free energy can be expressed as follows [14, 15]:
H
   
P   
(1)
2
where  1 and  2 are the susceptibilities of the two adjacent grains, respectively. 1 ,  2 are the corresponding
magnetic free energy, μ0 is permeability of vacuum, and H is the field strength. It is known that the difference
between  1 and  2 for pure copper is very small during grain growth process. So, the driving force acting on the
2
0
1
2
1
2
boundary of two crystals increases with the increasing of magnetic field strength.
In the present experiment, the results show high magnetic field can promote the growth of the recrystallized grains with
Cube orientation. This promotion effect increases with the increasing of magnetic field strength, especially when the
field is 8 T, where the result is more pronounced. According to equation (1), these results may be attributed to boundary
migration induced by magnetic field which effects increase with the field strength increasing. However, it is a very
complicated process that includes magnetic field effects as well as the evolution of recrystallization textures under
thermodynamics. Further detailed research on this process will be done in the next step.
(a)
(b)
(c)
(d)
(e)
(f)
Fig. 5: OIM (IPF + Grain Boundary) maps of specimens annealed with different magnetic field strength.
(a) 0T, (b) 4T, (c) 6T, (d) 8T, (e) 10T, (f) 12T.
Grain Diameter (m)
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0
2
4
6
8
10
12
Magnetic Field (T)
Fig. 6: Grain diameter of recrystallized grains in annealed specimens with different magnetic field strength.
Conclusion
A cold-rolled pure copper is annealed under a magnetic field with different magnetic field strength. It is obvious that
magnetic field annealing promote the growth of the recrystallized grains with Cube orientation. The average intensity of
Cube texture of the annealing specimens with the field is higher than that without the field (0T). As the strength of field
increases, the intensity of Cube texture strengthened to a maximum value at 8T, and then slightly decreased. The results
may be attributed to boundary migration induced by the magnetic field during grain growth process.
Acknowledgment
This work was supported by the National Natural Science Foundation of China (Grant No. 51201028), the “111” Project
(Grant No. B07015), the Fundamental Research Funds for the Central Universities (N130510001) and the Program for
New Century Excellent Talents in University (NCET-13-0104).
References
[1]
R Smoluchowski, R W Turner (1949), Journal of Applied Physics, 20, 745-749.
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
V S Bhandary, B D Cullity (1962), Transactions of the Metallurgical Society of AIME, 224, 1194-1196.
N Masahashi, M Matsuo, K Watanabe (1998), Journal of Material Research, 13, 457-461.
C M B Bacalthuk, G A C Branco, H Garmestani (2005), Materialwissenschaft und werkstofftechnik, 36, 561565.
D A Molodov, A D Sheikh-Ali (2004), Acta Materialia, 52, 4377-4383.
A D Sheikh-Ali, D A Molodov, H Garmestani (2007), Scripta Materialia, 46, 857-862.
S Bhaumik, X Molodova, D A Molodov (2006), Scripta Materialia, 55, 995-998.
A D Sheikh-Ali, H Garmestani (2008), Ceramic Transactions, 200, 413-419.
T Watanabe, Y Suzuki, S Tani (1990), Philosophical Magazine Letters, 62, 9-17.
S Tsurekawa, T Watanabe (2003), Materials Science Forum, 426-432, 3819-3824.
D A Molodov, A D Sheikh-Ali (2004), Acta Materialia, 52, 4377-4383.
A D Sheikh-Ali, D A Molodov, H Garmestani (2002), Scripta Materialia, 46, 857-862.
A D Sheikh-Ali, D A Molodov, H Garmestani (2005), Materials Processing in Magnetic fields, 91-101.
Molotskii M I (1760), Sov. Phys. Solid State, 33, 1760-1770.
Mullins W W (1956), Acta Metall, 4, 421-432.