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A high-ductility extruded Mg-Bi-Ca alloy
Journal Pre-proofs A high-ductility extruded Mg-Bi-Ca alloy S.J. Meng, H. Yu, S.D. Fan, Y.M. Kim, S.H. Park, W.M. Zhao, B.S. You, K.S. Shin PII: DOI: Reference:
S0167-577X(19)31698-2 https://doi.org/10.1016/j.matlet.2019.127066 MLBLUE 127066
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
1 October 2019 7 November 2019 20 November 2019
Please cite this article as: S.J. Meng, H. Yu, S.D. Fan, Y.M. Kim, S.H. Park, W.M. Zhao, B.S. You, K.S. Shin, A high-ductility extruded Mg-Bi-Ca alloy, Materials Letters (2019), doi: https://doi.org/10.1016/j.matlet. 2019.127066
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2019 Published by Elsevier B.V.
A high-ductility extruded Mg-Bi-Ca alloy S.J. Meng1,2, H. Yu1⁎, S.D. Fan1, Y.M. Kim2, S.H. Park3, W.M. Zhao1, B.S. You2, K.S. Shin4 1 School of Materials Science and Engineering, Hebei University of Technology, Tianjin, 300130, P.R. China 2 Magnesium Department, Korea Institute of Materials Science, Changwon, 51508, Republic of Korea 3 School of Materials Science and Engineering, Kyungpook National University, Daegu, 41566, Republic of Korea 4 School of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea ⁎ Corresponding author: Hui Yu E-mail address: [email protected]; [email protected]. Address: School of Materials Science and Engineering, Hebei University of Technology, Rd.#2 Dingzigu, Hongqiao District, Tianjin, China. Abstract In order to develop low cost Mg alloy with high ductility, a new micro-alloying rare earth free Mg-1.32Bi-0.72Ca (wt.%, BX11) alloy was successfully fabricated by single step extrusion and its microstructure, texture and tensile properties were investigated and discussed in this study. The as-extruded BX11 alloy demonstrates a weakened texture with <2-1-12> parallel to the extrusion direction (ED) and a fine dynamic recrystallized microstructure with both micro-scale Mg2Bi2Ca and Mg3Bi2 particles and nano-scale Mg2Ca and Mg3Bi2 precipitates, exhibiting an excellent tensile elongation of 43% at room temperature. This remarkably high ductility is mainly attributed to the refined microstructure as well as weakened <2-1-12>∥ED texture. Keywords Mg-Bi-Ca alloy, High ductility, Extrusion, Texture 1 Introduction Mg alloys, as the lightest metallic structure materials, have demonstrated great potential in transportation and aerospace industries nowadays. However, the widely
application of Mg alloys is still limited so far due to their poor ductility at low temperature
[1, 2].
Plenty of researches have proved that rare earth (RE) elements
addition in Mg alloys can significantly modify the texture, resulting in improvement of the ductility
[3].
However, the high cost and scarcity of natural resources make the
abundant use of RE elements unacceptable in commercial applications [2]. To overcome this drawback, other alloying strategy should be paid more attention. Ca seems to be a promising and popular element, which was reported to behave in a similar manner to RE elements when alloyed into Mg, and various Ca-containing Mg alloys with good mechanical properties have been developed
[2, 4, 5].
Moreover, it has recently been
reported that ductility of Mg can be enhanced by Bi addition Somekawa et al.
[6]
[5, 7].
For example,
produced fine-grain Mg-2.5Bi (all compositions quoted here are in
wt.%) binary alloy through extrusion at low temperatures of 105-210 °C, which exhibits a remarkable tensile elongation (EL.) of 170%. In addition, by combining rapidly solidification (RS) and extrusion processes, Remennik et al.
[8]
developed a
Mg-5Bi-1Ca alloy with high ductility (EL. > 40%). However, extrusion at very low temperatures or complexity RS involved route are not applicable for commercial mass production of Mg alloys to date. In this study, therefore, we attempted to develop a dilute RE-free Mg-Bi-Ca alloy with high ductility by simple extrusion, of which the microstructure and mechanical properties were also investigated. 2 Experimental procedures The ingot with a composition of Mg-1.32Bi-0.72Ca (denoted as BX11, hereafter) was fabricated by melting high purity Mg, Bi and Mg-20Ca master alloy in the electronic
resistance furnace. After homogenization treatment at 480 °C for 8 h, the billet with a dimension of Ø60 mm ×150 mm was machined and extruded at 300 °C with an extrusion ratio of 36 at a die-exit speed of 6 m/min. Microstructure and texture characterization was conducted by scanning electron microscopy (SEM) equipped with EDS, electron back-scatter diffraction (EBSD) and transmission electron microscope (TEM) equipped with energy-dispersive X-ray spectroscopy (EDX). The tensile tests were performed along the extrusion direction (ED) using a universal tensile testing machine (SUNS-UTM5105X). And commercial AZ31 billet extruded under the same conditions were also tested as a benchmark. Furthermore, the dislocation behavior of BX11 specimen tensioned to 15% (15%-strained BX11) was observed by TEM under two-beam diffraction conditions, and the tensile fracture was also examined by SEM to figure out the tensile deformation mechanism. 3 Results and discussion As presented in Fig. 1a, the as-extruded BX11 alloy demonstrates tensile yield strength of 135MPa and EL. of 43.3%, respectively. Compared to the 22% for commercial AZ31 extruded using same parameters, a remarkably high EL. of over 40% for BX11 alloy was obtained, which is higher than the as-extruded binary Mg-xCa (x = 0.4, 1 and 2)
[9],
and even higher than the RE-containing extruded Mg-3Y
Mg-1.58Zn-0.52Nd
[10].
[3]
and
Fig. 1b and c shows the SEM images of as-extruded BX11
alloy, which exhibits a fully dynamically recrystallized (DRXed) microstructure with an average grain size of about ~ 6 μm. Besides, a small amount of Mg-Bi-Ca and Mg-Bi phase with size of ~ 2 μm are also found to be aligned along the ED, based on EDS
analysis (see Fig. 1c), these micro-scale particles are expected to be Mg2Bi2Ca and Mg2Bi2 phase, respectively, which were also detected in previously Mg-6Bi-1Ca [8] and Mg-1.2Ca-12Bi alloys
[11].
Besides, TEM analysis were also conducted in order to
clarify the precipitation behavior of BX11 alloy. As shown in Fig. 1d and e, nano-scale dynamic precipitates are distributed in the DRXed grain matrix. The corresponding EDX analysis results (see Fig. 1e) reveal that the polyhedral particles of ~150 nm are enriched with Ca and Mg, and the rod-like particles of ~150 nm are enriched with Bi and Mg. Indexing of selected area diffraction patterns (SADP, see Fig. 1f and g) indicate that these particle phases are Mg2Ca (hcp, a= 0.62386 nm, c= 1.0146 nm) and Mg3Bi2 (hcp, a= 0.4666 nm, c= 0.7401 nm), respectively, differing from Mg2Bi2Ca and Mg3Bi2 observed in extruded Mg-6Bi-1Ca alloy
[8].
Although micro-scale Mg2Bi2Ca
and Mg2Bi2 particles of ~2 μm can be found in the alloy (see Fig. 1b and c), direct evidence of particle-stimulated nucleation (PSN) are not detected in present study. On the other hand, these fine micro-scale particles and nano precipitate can prevent the DRXed grain growth by restricting grain boundary migration through the well-known Zener pinning effect [12].
Fig. 1. (a) Tensile stress-strain curves of as-extruded BX11 and AZ31 alloy. SEM (b, c) and TEM (d, e) images of as-extruded BX11 alloy, and selected area diffraction patterns (f, g) of point E and F in (e), respectively. (ED: extrusion direction). Fig. 2a shows the inverse pole figure (IPF) map of the extruded BX11 alloy, which exhibits a fully DRXed structure with a mean size of ~6.3 μm. The corresponding IPF (Fig. 2b) illustrates that the BX11 alloy exhibits a dominant <2-1-12> ∥ ED texture with intensity of 2.28, which is completely different from the typical <10-10> ∥ED or < 2-1-10> ∥ED texture observed in extruded AZ31 [13] and Mg-Bi [6, 7] alloys. Similar texture component was also reported in as-extruded Mg-0.71Zn-0.36Ca-0.07Mn [14] and Mg-3Y [3] alloys. Considering the obvious texture diversity between as-extruded Mg-Bi binary [6, 7] and Ca-bearing BX11 alloy, it is reasonable to believe that the formation of <2-1-12> ∥ ED texture can be ascribed to the Ca addition into the BX11 alloy. Ca element was reported to be analogous to RE addition in Mg due to the similar feature in large atomic radius [15]. Further attempts are needed to dig out the mechanism behind.
Fig. 2. EBSD inverse pole figure map (a) and inverse pole figure (b) of as-extruded BX11 alloy. The high room temperature ductility is probably related to the fine microstructure and <2-1-12>∥ED texture characterized above. In case of BX11 alloy with <2-1-12>∥ED
texture, basal slip and/or {10-12} extension twins, rather than {10-11} contraction and {10-11}-{10-12} double twins
[10],
would become one of the main deformation modes.
Thus the rapid flow localization and early shear failure due to the localized twin-sized voids formation can be avoided. In addition, in Mg alloys with similar grain size of 6.3-6.6 μm, it is accepted that more grain boundaries tend to take part in the coordination of deformation
[3].
Here, as BX11 alloy has a fine DRXed microstructure
(~6.3 μm), stress concentration at grain boundaries and triple junctions in BX11 alloy will be greatly reduced, which in turn restrict the twin and eventually activate non-basal slip. The SEM images of tensile fracture surfaces of BX11 alloy are shown in Fig. 3a and b, and plenty of slip bands can be observed, indicating that lots of slip systems have been activated during deformation [16]. Furthermore, Fig. 3c and d presents TEM images of 15%-strained BX11 sample taken under two-beam diffraction conditions. No twins are observed in the sample. And the most of the dislocations visible under g = (0002) and invisible under g = (11-20), indicating that non-basal slip of dislocations become another main deformation modes during tensile deformation. Principally, non-basal slip of dislocations are activated in the BX11 alloy, which could accommodate the strains along the c-axis during deformation and thus greatly contributing to the high ductility. Finally, the low-cost Bi and Ca alloying elements and the one-step conventional extrusion process are expected to open ever-bright prospect for fabricating high-ductility RE-free Mg extrusion products for larger-scale industrial applications in near future.
Fig. 3. (a, b) Micrographs of the fracture surfaces of as-extruded BX11 alloy after tensile test to failure. (c, d) Bright field TEM images of BX11 alloy at tensile strain of 15% under two-beam diffraction conditions (Each micrograph shows the same area under different diffraction vector g). 4 Conclusions In summary, a novel RE-free BX11 alloy with a high-ductility of 43% was successfully fabricated by conventional extrusion. The as-extruded BX11 alloy demonstrates a weak <2-1-12> ∥ ED texture and a fine DRXed microstructure with both micro-scale Mg2Bi2Ca and Mg3Bi2 particles and nano-scale Mg2Ca and Mg3Bi2 precipitates built-in. The superior EL. is accommodated by the activity of non-basal slip of dislocations indeed. Acknowledgements The authors acknowledge financial support from the National Natural Science
Foundation of China (No. 51701060), the Natural Science Foundation of Hebei Province (No. E2016202130) and Tianjin city (No. 18JCQNJC03900), The Scientific Research Foundation for the Returned Overseas Chinese Scholars of Hebei Province (No. C20190505), 100 Foreign Experts Plan of Hebei Province, and the Joint Doctoral Training Foundation of HEBUT (No. 2018HW0008). References [1] Z. Wu, R. Ahmad, B. Yin, S. Sandloebes, W.A. Curtin, Science 359 (2018) 447-451.
[2] S.J. Meng, H. Yu, S.D. Fan, Q.Z. Li, S.H. Park, J.S. Suh, Y.M. Kim, X.L. Nan, M.Z. Bian, F.X. Yin, W.M. Zhao, B.S. You, K.S. Shin, Acta Metall. Sin. (Engl. Lett.) 32 (2019) 145-168. [3] N. Zhou, Z. Zhang, L. Jin, J. Dong, B. Chen, W. Ding, Mater. Des. 56 (2014) 966-974. [4] H. Pan, C. Yang, Y. Yang, Y. Dai, D. Zhou, L. Chai, Q. Huang, Q. Yang, S. Liu, Y. Ren, G. Qin, Mater. Lett. 237 (2018) 65-68. [5] N. Ikeo, M. Nishioka, T. Mukai, Mater. Lett. 223 (2018) 65-68. [6] H. Somekawa, A. Singh, Scripta Mater. 150 (2018) 26-30. [7] S. Meng, H. Yu, H. Zhang, H. Cui, Z. Wang, W. Zhao, Acta Metall. Sin. 52 (2016) 811-820. [8] S. Remennik, I. Bartsch, E. Willbold, F. Witte, D. Shechtman, Mater. Sci. Eng. B 176 (2011) 1653-1659. [9] Y.S. Jeong, W.J. Kim, Corros. Sci. 82 (2014) 392-403. [10] M.G. Jiang, C. Xu, T. Nakata, H. Yan, R.S. Chen, S. Kamado, Mater. Sci. Eng. A 667 (2016) 233-239. [11] H.Y. Tok, E. Hamzah, H.R. Bakhsheshi-Rad, J. Alloy. Comp. 640 (2015) 335-346. [12] J.D. Robson, D.T. Henry, B. Davis, Mater. Sci. Eng. A 528 (2011) 4239-4247. [13] S. Meng, H. Yu, H. Zhang, H. Cui, S.H. Park, W. Zhao, B.S. You, Mater. Sci. Eng. A 690 (2017) 80-87. [14] M.G. Jiang, C. Xu, T. Nakata, H. Yan, R.S. Chen, S. Kamado, Mater. Sci. Eng. A 678 (2016) 329-338. [15] N. Stanford, D. Atwell, A. Beer, C. Davies, M.R. Barnett, Scripta Mater. 59 (2008) 772-775. [16] B.L. Wu, Y.H. Zhao, X.H. Du, Y.D. Zhang, F. Wagner, C. Esling, Mater. Sci. Eng. A 527 (2010) 4334-4340.
Declaration of Interest Statement
We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled.
Highlights 1. A RE-free Mg-1.32Bi-0.72Ca (wt.%, BX11) alloy was fabricated by one-step extrusion. 2. The extruded sample has fine microstructure (~6μm) and weak <2-1-12> ∥ ED texture. 3. The extruded BX11 alloy exhibits an excellent elongation room temperature of 43%.
S0167-577X(19)31698-2 https://doi.org/10.1016/j.matlet.2019.127066 MLBLUE 127066
To appear in:
Materials Letters
Received Date: Revised Date: Accepted Date:
1 October 2019 7 November 2019 20 November 2019
Please cite this article as: S.J. Meng, H. Yu, S.D. Fan, Y.M. Kim, S.H. Park, W.M. Zhao, B.S. You, K.S. Shin, A high-ductility extruded Mg-Bi-Ca alloy, Materials Letters (2019), doi: https://doi.org/10.1016/j.matlet. 2019.127066
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2019 Published by Elsevier B.V.
A high-ductility extruded Mg-Bi-Ca alloy S.J. Meng1,2, H. Yu1⁎, S.D. Fan1, Y.M. Kim2, S.H. Park3, W.M. Zhao1, B.S. You2, K.S. Shin4 1 School of Materials Science and Engineering, Hebei University of Technology, Tianjin, 300130, P.R. China 2 Magnesium Department, Korea Institute of Materials Science, Changwon, 51508, Republic of Korea 3 School of Materials Science and Engineering, Kyungpook National University, Daegu, 41566, Republic of Korea 4 School of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea ⁎ Corresponding author: Hui Yu E-mail address: [email protected]; [email protected]. Address: School of Materials Science and Engineering, Hebei University of Technology, Rd.#2 Dingzigu, Hongqiao District, Tianjin, China. Abstract In order to develop low cost Mg alloy with high ductility, a new micro-alloying rare earth free Mg-1.32Bi-0.72Ca (wt.%, BX11) alloy was successfully fabricated by single step extrusion and its microstructure, texture and tensile properties were investigated and discussed in this study. The as-extruded BX11 alloy demonstrates a weakened texture with <2-1-12> parallel to the extrusion direction (ED) and a fine dynamic recrystallized microstructure with both micro-scale Mg2Bi2Ca and Mg3Bi2 particles and nano-scale Mg2Ca and Mg3Bi2 precipitates, exhibiting an excellent tensile elongation of 43% at room temperature. This remarkably high ductility is mainly attributed to the refined microstructure as well as weakened <2-1-12>∥ED texture. Keywords Mg-Bi-Ca alloy, High ductility, Extrusion, Texture 1 Introduction Mg alloys, as the lightest metallic structure materials, have demonstrated great potential in transportation and aerospace industries nowadays. However, the widely
application of Mg alloys is still limited so far due to their poor ductility at low temperature
[1, 2].
Plenty of researches have proved that rare earth (RE) elements
addition in Mg alloys can significantly modify the texture, resulting in improvement of the ductility
[3].
However, the high cost and scarcity of natural resources make the
abundant use of RE elements unacceptable in commercial applications [2]. To overcome this drawback, other alloying strategy should be paid more attention. Ca seems to be a promising and popular element, which was reported to behave in a similar manner to RE elements when alloyed into Mg, and various Ca-containing Mg alloys with good mechanical properties have been developed
[2, 4, 5].
Moreover, it has recently been
reported that ductility of Mg can be enhanced by Bi addition Somekawa et al.
[6]
[5, 7].
For example,
produced fine-grain Mg-2.5Bi (all compositions quoted here are in
wt.%) binary alloy through extrusion at low temperatures of 105-210 °C, which exhibits a remarkable tensile elongation (EL.) of 170%. In addition, by combining rapidly solidification (RS) and extrusion processes, Remennik et al.
[8]
developed a
Mg-5Bi-1Ca alloy with high ductility (EL. > 40%). However, extrusion at very low temperatures or complexity RS involved route are not applicable for commercial mass production of Mg alloys to date. In this study, therefore, we attempted to develop a dilute RE-free Mg-Bi-Ca alloy with high ductility by simple extrusion, of which the microstructure and mechanical properties were also investigated. 2 Experimental procedures The ingot with a composition of Mg-1.32Bi-0.72Ca (denoted as BX11, hereafter) was fabricated by melting high purity Mg, Bi and Mg-20Ca master alloy in the electronic
resistance furnace. After homogenization treatment at 480 °C for 8 h, the billet with a dimension of Ø60 mm ×150 mm was machined and extruded at 300 °C with an extrusion ratio of 36 at a die-exit speed of 6 m/min. Microstructure and texture characterization was conducted by scanning electron microscopy (SEM) equipped with EDS, electron back-scatter diffraction (EBSD) and transmission electron microscope (TEM) equipped with energy-dispersive X-ray spectroscopy (EDX). The tensile tests were performed along the extrusion direction (ED) using a universal tensile testing machine (SUNS-UTM5105X). And commercial AZ31 billet extruded under the same conditions were also tested as a benchmark. Furthermore, the dislocation behavior of BX11 specimen tensioned to 15% (15%-strained BX11) was observed by TEM under two-beam diffraction conditions, and the tensile fracture was also examined by SEM to figure out the tensile deformation mechanism. 3 Results and discussion As presented in Fig. 1a, the as-extruded BX11 alloy demonstrates tensile yield strength of 135MPa and EL. of 43.3%, respectively. Compared to the 22% for commercial AZ31 extruded using same parameters, a remarkably high EL. of over 40% for BX11 alloy was obtained, which is higher than the as-extruded binary Mg-xCa (x = 0.4, 1 and 2)
[9],
and even higher than the RE-containing extruded Mg-3Y
Mg-1.58Zn-0.52Nd
[10].
[3]
and
Fig. 1b and c shows the SEM images of as-extruded BX11
alloy, which exhibits a fully dynamically recrystallized (DRXed) microstructure with an average grain size of about ~ 6 μm. Besides, a small amount of Mg-Bi-Ca and Mg-Bi phase with size of ~ 2 μm are also found to be aligned along the ED, based on EDS
analysis (see Fig. 1c), these micro-scale particles are expected to be Mg2Bi2Ca and Mg2Bi2 phase, respectively, which were also detected in previously Mg-6Bi-1Ca [8] and Mg-1.2Ca-12Bi alloys
[11].
Besides, TEM analysis were also conducted in order to
clarify the precipitation behavior of BX11 alloy. As shown in Fig. 1d and e, nano-scale dynamic precipitates are distributed in the DRXed grain matrix. The corresponding EDX analysis results (see Fig. 1e) reveal that the polyhedral particles of ~150 nm are enriched with Ca and Mg, and the rod-like particles of ~150 nm are enriched with Bi and Mg. Indexing of selected area diffraction patterns (SADP, see Fig. 1f and g) indicate that these particle phases are Mg2Ca (hcp, a= 0.62386 nm, c= 1.0146 nm) and Mg3Bi2 (hcp, a= 0.4666 nm, c= 0.7401 nm), respectively, differing from Mg2Bi2Ca and Mg3Bi2 observed in extruded Mg-6Bi-1Ca alloy
[8].
Although micro-scale Mg2Bi2Ca
and Mg2Bi2 particles of ~2 μm can be found in the alloy (see Fig. 1b and c), direct evidence of particle-stimulated nucleation (PSN) are not detected in present study. On the other hand, these fine micro-scale particles and nano precipitate can prevent the DRXed grain growth by restricting grain boundary migration through the well-known Zener pinning effect [12].
Fig. 1. (a) Tensile stress-strain curves of as-extruded BX11 and AZ31 alloy. SEM (b, c) and TEM (d, e) images of as-extruded BX11 alloy, and selected area diffraction patterns (f, g) of point E and F in (e), respectively. (ED: extrusion direction). Fig. 2a shows the inverse pole figure (IPF) map of the extruded BX11 alloy, which exhibits a fully DRXed structure with a mean size of ~6.3 μm. The corresponding IPF (Fig. 2b) illustrates that the BX11 alloy exhibits a dominant <2-1-12> ∥ ED texture with intensity of 2.28, which is completely different from the typical <10-10> ∥ED or < 2-1-10> ∥ED texture observed in extruded AZ31 [13] and Mg-Bi [6, 7] alloys. Similar texture component was also reported in as-extruded Mg-0.71Zn-0.36Ca-0.07Mn [14] and Mg-3Y [3] alloys. Considering the obvious texture diversity between as-extruded Mg-Bi binary [6, 7] and Ca-bearing BX11 alloy, it is reasonable to believe that the formation of <2-1-12> ∥ ED texture can be ascribed to the Ca addition into the BX11 alloy. Ca element was reported to be analogous to RE addition in Mg due to the similar feature in large atomic radius [15]. Further attempts are needed to dig out the mechanism behind.
Fig. 2. EBSD inverse pole figure map (a) and inverse pole figure (b) of as-extruded BX11 alloy. The high room temperature ductility is probably related to the fine microstructure and <2-1-12>∥ED texture characterized above. In case of BX11 alloy with <2-1-12>∥ED
texture, basal slip and/or {10-12} extension twins, rather than {10-11} contraction and {10-11}-{10-12} double twins
[10],
would become one of the main deformation modes.
Thus the rapid flow localization and early shear failure due to the localized twin-sized voids formation can be avoided. In addition, in Mg alloys with similar grain size of 6.3-6.6 μm, it is accepted that more grain boundaries tend to take part in the coordination of deformation
[3].
Here, as BX11 alloy has a fine DRXed microstructure
(~6.3 μm), stress concentration at grain boundaries and triple junctions in BX11 alloy will be greatly reduced, which in turn restrict the twin and eventually activate non-basal slip. The SEM images of tensile fracture surfaces of BX11 alloy are shown in Fig. 3a and b, and plenty of slip bands can be observed, indicating that lots of slip systems have been activated during deformation [16]. Furthermore, Fig. 3c and d presents TEM images of 15%-strained BX11 sample taken under two-beam diffraction conditions. No twins are observed in the sample. And the most of the dislocations visible under g = (0002) and invisible under g = (11-20), indicating that non-basal slip of
Fig. 3. (a, b) Micrographs of the fracture surfaces of as-extruded BX11 alloy after tensile test to failure. (c, d) Bright field TEM images of BX11 alloy at tensile strain of 15% under two-beam diffraction conditions (Each micrograph shows the same area under different diffraction vector g). 4 Conclusions In summary, a novel RE-free BX11 alloy with a high-ductility of 43% was successfully fabricated by conventional extrusion. The as-extruded BX11 alloy demonstrates a weak <2-1-12> ∥ ED texture and a fine DRXed microstructure with both micro-scale Mg2Bi2Ca and Mg3Bi2 particles and nano-scale Mg2Ca and Mg3Bi2 precipitates built-in. The superior EL. is accommodated by the activity of non-basal slip of
Foundation of China (No. 51701060), the Natural Science Foundation of Hebei Province (No. E2016202130) and Tianjin city (No. 18JCQNJC03900), The Scientific Research Foundation for the Returned Overseas Chinese Scholars of Hebei Province (No. C20190505), 100 Foreign Experts Plan of Hebei Province, and the Joint Doctoral Training Foundation of HEBUT (No. 2018HW0008). References [1] Z. Wu, R. Ahmad, B. Yin, S. Sandloebes, W.A. Curtin, Science 359 (2018) 447-451.
[2] S.J. Meng, H. Yu, S.D. Fan, Q.Z. Li, S.H. Park, J.S. Suh, Y.M. Kim, X.L. Nan, M.Z. Bian, F.X. Yin, W.M. Zhao, B.S. You, K.S. Shin, Acta Metall. Sin. (Engl. Lett.) 32 (2019) 145-168. [3] N. Zhou, Z. Zhang, L. Jin, J. Dong, B. Chen, W. Ding, Mater. Des. 56 (2014) 966-974. [4] H. Pan, C. Yang, Y. Yang, Y. Dai, D. Zhou, L. Chai, Q. Huang, Q. Yang, S. Liu, Y. Ren, G. Qin, Mater. Lett. 237 (2018) 65-68. [5] N. Ikeo, M. Nishioka, T. Mukai, Mater. Lett. 223 (2018) 65-68. [6] H. Somekawa, A. Singh, Scripta Mater. 150 (2018) 26-30. [7] S. Meng, H. Yu, H. Zhang, H. Cui, Z. Wang, W. Zhao, Acta Metall. Sin. 52 (2016) 811-820. [8] S. Remennik, I. Bartsch, E. Willbold, F. Witte, D. Shechtman, Mater. Sci. Eng. B 176 (2011) 1653-1659. [9] Y.S. Jeong, W.J. Kim, Corros. Sci. 82 (2014) 392-403. [10] M.G. Jiang, C. Xu, T. Nakata, H. Yan, R.S. Chen, S. Kamado, Mater. Sci. Eng. A 667 (2016) 233-239. [11] H.Y. Tok, E. Hamzah, H.R. Bakhsheshi-Rad, J. Alloy. Comp. 640 (2015) 335-346. [12] J.D. Robson, D.T. Henry, B. Davis, Mater. Sci. Eng. A 528 (2011) 4239-4247. [13] S. Meng, H. Yu, H. Zhang, H. Cui, S.H. Park, W. Zhao, B.S. You, Mater. Sci. Eng. A 690 (2017) 80-87. [14] M.G. Jiang, C. Xu, T. Nakata, H. Yan, R.S. Chen, S. Kamado, Mater. Sci. Eng. A 678 (2016) 329-338. [15] N. Stanford, D. Atwell, A. Beer, C. Davies, M.R. Barnett, Scripta Mater. 59 (2008) 772-775. [16] B.L. Wu, Y.H. Zhao, X.H. Du, Y.D. Zhang, F. Wagner, C. Esling, Mater. Sci. Eng. A 527 (2010) 4334-4340.
Declaration of Interest Statement
We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled.
Highlights 1. A RE-free Mg-1.32Bi-0.72Ca (wt.%, BX11) alloy was fabricated by one-step extrusion. 2. The extruded sample has fine microstructure (~6μm) and weak <2-1-12> ∥ ED texture. 3. The extruded BX11 alloy exhibits an excellent elongation room temperature of 43%.