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Nickel DABiTS-tapes as a promising alternative to RABiTS-tapes
Physica C 408–410 (2004) 906–907 www.elsevier.com/locate/physc
Nickel DABiTS-tapes as a promising alternative to RABiTS-tapes J. Eickemeyer *, D. Selbmann, R. Opitz, V. Subramanya Sarma, B. Holzapfel, L. Schultz IFW Dresden, Leibniz-Institute for Solid State and Materials Research Dresden, P.O. Box 270016, D-01171 Dresden, Germany
Abstract Drawing of nickel through wedge shaped dies as well as through loose rolls with subsequent annealing was performed in order produce a sharp recrystallisation cube texture. The drawing/annealing processing was very effective and the obtained tapes were designated as DABiTS. 2004 Elsevier B.V. All rights reserved. Keywords: Tape drawing; Tape rolling; Recrystallisation; Cube texture
1. Introduction Cube textured nickel tapes are used as substrate material for YBCO coated conductors as a variant for flexible high temperature superconductors [1]. These tapes are RABiTS tapes, which means rolling assisted biaxially textured substrates tapes [2]. The preparation of these tapes occurs by intensive cold rolling and subsequent recrystallisation treatment, as well known for many decades [3]. In this study the convenience of drawing techniques was investigated in order to produce such cube textured nickel tapes. This question seemed to be of basic interest and the answer could result in some additional knowledge how to get a sharp cube texture in practice.
2. Experimental Drawing through wedge shaped dies as well as drawing through loose rolls with subsequent annealing
* Corresponding author. Tel.: +49-351-4659-695; fax: +49351-4659-541/320. E-mail address: [email protected] (J. Eickemeyer).
was carried out in order to produce DABiTS tapes [4], which stands for drawing assisted biaxially textured substrate tapes. The drawing/annealing procedures were investigated using pure nickel (99.98 mass% purity). The initial dimensions of the nickel pieces were (10 · 10 · 120) mm for the drawing experiments and (10 · 10 · 50) mm for the rolling procedure. Firstly, the nickel bars were drawn step by step from 10 to 2.5 mm thickness through rigid dies (eh ¼ 75%). Secondly, one subsequent forming route was to draw the 2.5 mm thick strips further step by step through rigid dies down to a minimum thickness of 0.42 mm (eh ¼ 95:8%) and another route was to draw the 2.5 mm thick strips through freely rotating rolls step by step down to a minimum thickness of 80 lm (eh ¼ 99:2%). On the other hand, the 10 mm thick bars were rolled step by step to a minimum thickness of 80 lm. The final samples as well as the samples at intermediate reductions in thickness were recrystallised in order to get information about the degree of texture development. Recrystallisation treatments were performed at 600 and at 800 C in a gaseous hydrogen atmosphere. The annealing time was 30 min. The achieved texture qualities were analysed by Xray and electron back scattering diffraction (EBSD) measurements and were compared between the different preparation methods.
0921-4534/$ - see front matter 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.physc.2004.03.157
J. Eickemeyer et al. / Physica C 408–410 (2004) 906–907
907
3. Results Full width half maximum (FWHM) values of the Xray (1 1 1) poles down to about 8 were measured after 99% reduction of thickness and an annealing process at 600 and 800 C, respectively. As obvious from Table 1, there is a clear tendency of increasing texture sharpness with increasing reduction of the thickness after the 600 C annealing treatment. The DABiTS samples, which were cold drawn through freely rotating rolls, show a more effective texture forming behaviour than the cold rolled RABiTS tapes. By this means, a second manufacturing route was found in order to produce cube textured nickel tapes besides the well known rolling assisted process for the flexible textured nickel tapes [4]. Fig. 1 illustrates the cube texture forming tendency for the different cold forming operations, which were applied before the final annealing treatment. The relative (1 0 0) X-ray reflection intensities from H–2H measurements show that drawing is more effective than rolling. Just at the highest applied degrees of deformation rolling results in a comparable efficiency of texturing. Drawing through loose rolls appeared as the most effective cold forming variant for the formation of the recrystallisation cube texture in comparison with the drawing through wedge shaped dies as well as the rolling procedure.
Table 1 Development of FWHM values of the X-ray (1 1 1) poles with tape thickness of RABiTS and DABiTS after annealing at 600 C for 30 min RABiTS FWHM ()
DABiTS FWHM ()
500 180 80
17.4 11.3 8.9
14.4 9.4 8.2
Relative (100) intensity I(100)
Tape thickness (lm)
Fig. 2. Fraction of cube textured grains at the surface of a nickel-strip (a) cold rolled from 10 to 0.5 mm and annealed at 800 C for 30 min and (b) cold drawn from 10 to 0.5 mm and annealed at 800 C for 30 min.
Fig. 2 gives evidence of the increased fraction of cube oriented grains after drawing and annealing at 800 C compared with rolling and annealing for a 0.5 mm thick tape as measured by EBSD. At this state of intermediate treatment the RABiTS sample shows 21% of cube oriented grains (Fig. 2a) and the DABiTS sample a fraction of 41% cube texture (Fig. 2b).
4. Conclusions Experiments have clearly shown that the processing route by drawing and annealing can be used to produce highly cube textured nickel substrate tapes (DABiTS). The processing route by means of cold drawing seems to be more effective for the formation of the cube texture than the presently used rolling assisted route (RABiTS).
Acknowledgements 1.0
We would like to thank Dr Horst Wendrock and Dr Dietrich Schl€ afer from IFW Dresden for helpful investigations.
0.9 Drawing through a rigid die Drawing through rolls
0.8 0.7
Rolling 0.6 90
91
92
93
94
95
96
97
98
99
References
Reduction of thickness. εh[%]
Fig. 1. Relative X-ray intensity of (1 0 0) reflections Ið1 0 0Þ of nickel tapes after different cold forming procedures and subsequent recrystallisation at 600 C for 30 min.
[1] [2] [3] [4]
D.P. Norton et al., Science 275 (1996) 755. A. Goyal et al., Appl. Phys. Lett. 69 (1996) 1795. W.G. Burgers, J.L. Snoek, Z. Metallkde 27 (1935) 158–160. J. Eickemeyer et al., German Patent, DE 101 43 680.
Nickel DABiTS-tapes as a promising alternative to RABiTS-tapes J. Eickemeyer *, D. Selbmann, R. Opitz, V. Subramanya Sarma, B. Holzapfel, L. Schultz IFW Dresden, Leibniz-Institute for Solid State and Materials Research Dresden, P.O. Box 270016, D-01171 Dresden, Germany
Abstract Drawing of nickel through wedge shaped dies as well as through loose rolls with subsequent annealing was performed in order produce a sharp recrystallisation cube texture. The drawing/annealing processing was very effective and the obtained tapes were designated as DABiTS. 2004 Elsevier B.V. All rights reserved. Keywords: Tape drawing; Tape rolling; Recrystallisation; Cube texture
1. Introduction Cube textured nickel tapes are used as substrate material for YBCO coated conductors as a variant for flexible high temperature superconductors [1]. These tapes are RABiTS tapes, which means rolling assisted biaxially textured substrates tapes [2]. The preparation of these tapes occurs by intensive cold rolling and subsequent recrystallisation treatment, as well known for many decades [3]. In this study the convenience of drawing techniques was investigated in order to produce such cube textured nickel tapes. This question seemed to be of basic interest and the answer could result in some additional knowledge how to get a sharp cube texture in practice.
2. Experimental Drawing through wedge shaped dies as well as drawing through loose rolls with subsequent annealing
* Corresponding author. Tel.: +49-351-4659-695; fax: +49351-4659-541/320. E-mail address: [email protected] (J. Eickemeyer).
was carried out in order to produce DABiTS tapes [4], which stands for drawing assisted biaxially textured substrate tapes. The drawing/annealing procedures were investigated using pure nickel (99.98 mass% purity). The initial dimensions of the nickel pieces were (10 · 10 · 120) mm for the drawing experiments and (10 · 10 · 50) mm for the rolling procedure. Firstly, the nickel bars were drawn step by step from 10 to 2.5 mm thickness through rigid dies (eh ¼ 75%). Secondly, one subsequent forming route was to draw the 2.5 mm thick strips further step by step through rigid dies down to a minimum thickness of 0.42 mm (eh ¼ 95:8%) and another route was to draw the 2.5 mm thick strips through freely rotating rolls step by step down to a minimum thickness of 80 lm (eh ¼ 99:2%). On the other hand, the 10 mm thick bars were rolled step by step to a minimum thickness of 80 lm. The final samples as well as the samples at intermediate reductions in thickness were recrystallised in order to get information about the degree of texture development. Recrystallisation treatments were performed at 600 and at 800 C in a gaseous hydrogen atmosphere. The annealing time was 30 min. The achieved texture qualities were analysed by Xray and electron back scattering diffraction (EBSD) measurements and were compared between the different preparation methods.
0921-4534/$ - see front matter 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.physc.2004.03.157
J. Eickemeyer et al. / Physica C 408–410 (2004) 906–907
907
3. Results Full width half maximum (FWHM) values of the Xray (1 1 1) poles down to about 8 were measured after 99% reduction of thickness and an annealing process at 600 and 800 C, respectively. As obvious from Table 1, there is a clear tendency of increasing texture sharpness with increasing reduction of the thickness after the 600 C annealing treatment. The DABiTS samples, which were cold drawn through freely rotating rolls, show a more effective texture forming behaviour than the cold rolled RABiTS tapes. By this means, a second manufacturing route was found in order to produce cube textured nickel tapes besides the well known rolling assisted process for the flexible textured nickel tapes [4]. Fig. 1 illustrates the cube texture forming tendency for the different cold forming operations, which were applied before the final annealing treatment. The relative (1 0 0) X-ray reflection intensities from H–2H measurements show that drawing is more effective than rolling. Just at the highest applied degrees of deformation rolling results in a comparable efficiency of texturing. Drawing through loose rolls appeared as the most effective cold forming variant for the formation of the recrystallisation cube texture in comparison with the drawing through wedge shaped dies as well as the rolling procedure.
Table 1 Development of FWHM values of the X-ray (1 1 1) poles with tape thickness of RABiTS and DABiTS after annealing at 600 C for 30 min RABiTS FWHM ()
DABiTS FWHM ()
500 180 80
17.4 11.3 8.9
14.4 9.4 8.2
Relative (100) intensity I(100)
Tape thickness (lm)
Fig. 2. Fraction of cube textured grains at the surface of a nickel-strip (a) cold rolled from 10 to 0.5 mm and annealed at 800 C for 30 min and (b) cold drawn from 10 to 0.5 mm and annealed at 800 C for 30 min.
Fig. 2 gives evidence of the increased fraction of cube oriented grains after drawing and annealing at 800 C compared with rolling and annealing for a 0.5 mm thick tape as measured by EBSD. At this state of intermediate treatment the RABiTS sample shows 21% of cube oriented grains (Fig. 2a) and the DABiTS sample a fraction of 41% cube texture (Fig. 2b).
4. Conclusions Experiments have clearly shown that the processing route by drawing and annealing can be used to produce highly cube textured nickel substrate tapes (DABiTS). The processing route by means of cold drawing seems to be more effective for the formation of the cube texture than the presently used rolling assisted route (RABiTS).
Acknowledgements 1.0
We would like to thank Dr Horst Wendrock and Dr Dietrich Schl€ afer from IFW Dresden for helpful investigations.
0.9 Drawing through a rigid die Drawing through rolls
0.8 0.7
Rolling 0.6 90
91
92
93
94
95
96
97
98
99
References
Reduction of thickness. εh[%]
Fig. 1. Relative X-ray intensity of (1 0 0) reflections Ið1 0 0Þ of nickel tapes after different cold forming procedures and subsequent recrystallisation at 600 C for 30 min.
[1] [2] [3] [4]
D.P. Norton et al., Science 275 (1996) 755. A. Goyal et al., Appl. Phys. Lett. 69 (1996) 1795. W.G. Burgers, J.L. Snoek, Z. Metallkde 27 (1935) 158–160. J. Eickemeyer et al., German Patent, DE 101 43 680.