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Hydrogen permeation properties of Pd-coated Ni60Nb30Ta10 amorphous alloy membrane
Materials Science and Engineering A 449–451 (2007) 934–936
Hydrogen permeation properties of Pd-coated Ni60Nb30Ta10 amorphous alloy membrane K.B. Kim a,∗ , K.D. Kim a,b , D.Y. Lee a , Y.C. Kim a , E. Fleury a , D.H. Kim b a
Advanced Materials Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea b Department of Metallurgical Engineering, Center for Non-crystalline Materials, Yonsei University, Seoul 120-749, South Korea Received 25 August 2005; received in revised form 20 February 2006; accepted 1 March 2006
Abstract The hydrogen permeability of a melt-spun Ni60 Nb30 Ta10 (numbers indicate at.%) amorphous alloy has been examined in the temperature range of 573–673 K and pressures up to 0.6 MPa. Pd60 Cu40 alloy membranes were also evaluated in the same manner. The permeated hydrogen flux was increased with increasing the temperature and the difference of hydrogen pressure between the feed side and permeate side of the membrane. The maximum hydrogen permeability of the Ni60 Nb30 Ta10 glassy alloy was 4.13 × 10−8 mol/m s Pa1/2 at 673 K, which was almost twice the permeability of Pd60 Cu40 alloy measured under the same conditions. These permeation characteristics imply the possibility of future practical application of the glassy alloys as the hydrogen separation membrane. © 2006 Elsevier B.V. All rights reserved. Keywords: Hydrogen permeation; Hydrogen separation membrane; Ni60 Nb30 Ta10 amorphous alloy; Pd60 Cu40 alloy
1. Introduction Hydrogen production is expected to markedly increase, because high purity hydrogen is required in many applications, for example, as an energy source of fuel cells, semiconductor manufacture and petrochemical industry [1–3]. At present, the most effective method to produce high purity hydrogen uses hydrogen separative membranes [4,5]. Progress in membrane technology has the potential to improve the efficiency of hydrogen separation and to reduce the cost associated with hydrogen production. Palladium and its alloys were first identified as a highly hydrogen permeable material and it is still used for high performance hydrogen separation applications today [6]. The advantages of palladium over other membrane materials are the catalytic surface, high hydrogen permeability, infinite hydrogen selectivity, corrosion resistance, and temperature stability. However, owing to its cost and in order to supply hydrogen at a reduced cost for the coming hydrogen energy society, it is desirable to develop new membrane alloys with minimum addition or absence of Pd metal.
∗
Corresponding author. Tel.: +82 2 958 5454; fax: +82 2 958 5449. E-mail address: [email protected] (K.B. Kim).
0921-5093/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2006.03.144
Non-Pd-based membrane alloys, such as V-based alloys, have been investigated by many research groups [7,8]. Values of the hydrogen permeation were satisfactory, however the drawback of this alloys are the poor selectivity and the sensibility of hydrogen embrittlement [9,10]. It is well known that amorphous alloys have various excellent characteristics, as for example high strength and high corrosion resistance in comparison with crystalline ones [11,12]. Therefore, the objective of this study is an attempt to develop amorphous alloys as new hydrogen permeation membrane materials. In this paper, we will report the production of amorphous Ni60 Nb30 Ta10 (numbers indicate at.%) alloy by the melt-spinning method and we will examine the hydrogen permeability between 573 and 673 K for a pressure up to 0.6 MPa. 2. Experimental Ni60 Nb30 Ta10 and Pd60 Cu40 alloy ingots were prepared by arc-melting pure metals in an argon atmosphere. Melt-spun ribbons were produced by the single roller melt-spinning technique in an argon atmosphere. The Ni60 Nb30 Ta10 ribbon was about 6 mm wide and 70 m thick, and the Pd60 Cu40 ribbon was about 10 mm wide and around 30 m thick. The amorphicity of the melt-spun Ni60 Nb30 Ta10 ribbon was investigated by Xray diffractometry.
K.B. Kim et al. / Materials Science and Engineering A 449–451 (2007) 934–936
Palladium thin film of about 60 nm in thickness was deposited on both sides of specimens by a sputtering technique as an active catalyst for hydrogen dissociation and recombination during permeation. Hydrogen permeation measurements were performed with a conventional gas-permeation technique in the temperature range of 573–673 K, at the hydrogen pressure up to 0.6 MPa. Membrane specimens were mounted in the gas-permeation cell. The permeation area was about 25 mm2 . A pure hydrogen gas was introduced to one side (feed side) of the membrane and then the flow rate of effluent hydrogen gas from the other side (permeate side) was measured by the flow meter. After evacuating by means of a rotary pump, pure helium gas was first introduced for purge, and the specimen membranes were heated up to a given test temperature in a helium atmosphere by an electrical furnace. Then, the evacuation by a rotary pump and the subsequent introduction of a pure hydrogen gas were repeated to eliminate the atmospherical contamination from the permeation cell. Also, an activation treatment was done by exposing hydrogen gas both sides of the membrane to a pressure of 0.2 MPa for 1 h at the test temperature before measuring the hydrogen permeation rate. 3. Results and discussion The hydrogen permeability of Ni60 Nb30 Ta10 amorphous alloy was measured up to 673 K under a hydrogen pressure at a feed side of the membrane of 0.6 MPa. The hydrogen permeation rate was measured as a function of the difference of hydrogen pressure between the feed side and the permeate side of the membrane as shown in Fig. 1. The variation of the hydrogen flux was found to increase proportionally with the square roots of the pressure difference between the feed side and permeate side of the membrane. Also it is worth noticing that Ni60 Nb30 Ta10 amorphous alloy was not broken after permeation test in the range of 573–673 K, which can be explained by the glass transition temperature of this alloy significantly larger than the testing temperature and the resistance to hydrogen embrittlement.
Fig. 2. Arrhenius plot of the hydrogen permeability of a melt-spun Ni60 Nb30 Ta10 glassy alloy and Pd60 Cu40 alloy as a function of inversed temperature.
Fig. 2 shows the hydrogen permeability of the Ni60 Nb30 Ta10 amorphous alloy membrane as a function of the inverse temperature. The permeation data of the Pd60 Cu40 alloy was also measured under identical condition in order to compare with the hydrogen permeability of Ni60 Nb30 Ta10 amorphous alloy and to check our hydrogen permeation equipment. The hydrogen flux through the Pd60 Cu40 membrane was found to increase up to 673 K and then dropped for further increase of the temperature. In Pd–Cu alloy membrane, a maximum hydrogen permeability of 2.1 × 10−8 mol/m s Pa1/2 at 673 K was measured which is in agreement with published data [6]. The hydrogen flux dropped over 673 K is believed to result from the phase transformation from bcc to mixed fcc and bcc structures. It is well known that owing to its lesser atomic packing, the hydrogen permeation is easier in bcc structure than that of fcc structure. For Ni–Nb–Ta alloy, the hydrogen permeability increases exponentially with increasing temperature. The maximum permeability of Pd-coated Ni60 Nb30 Ta10 amorphous alloy membrane was measured to be 4.13 × 10−8 mol/m s Pa1/2 at 673 K that is almost twice the values of the hydrogen permeability for Pd60 Cu40 alloy. In general, when it is controlled by diffusion of hydrogen atoms in the membrane, hydrogen permeation through a metal membrane is proportional to the square root of hydrogen partial pressure, p1/2 , so that the hydrogen flux (hydrogen permeation rate), J, should be written as follows J=
Fig. 1. Hydrogen flux of melt-spun Ni60 Nb30 Ta10 amorphous alloy as a function of the difference in the square root of hydrogen pressures on both sides of the membrane.
935
P¯ p1/2 d
(1)
where d is the membrane thickness and P¯ is the permeability. Therefore, the permeability as a material constant is not dependent on the membrane thickness and can be compared to the other membrane. But the hydrogen flux, which is very important factor for the production of hydrogen gas, is very dependent on the membrane thickness. In order to produce more the hydrogen gas through a metal membrane it is very important to make the thinner membrane.
936
K.B. Kim et al. / Materials Science and Engineering A 449–451 (2007) 934–936
Fig. 4 shows the XRD patterns of the as-melt-spun and Pdcoated Ni60 Nb30 Ta10 amorphous alloy membranes before and after permeation test. In addition to the halo peak of the amorphous phase, the Pd peaks were observed in the Pd-coated Ni60 Nb30 Ta10 amorphous alloy membrane before permeation test. After hydrogen permeation test, hydride peaks appeared with Pd peaks indicating that some Pd atoms combined with hydrogen atom to form palladium hydride. 4. Summary
Fig. 3. The DSC curves of melt-spun and Pd-coated Ni60 Nb30 Ta10 amorphous alloy membrane before and after permeation test. Table 1 The Tg , Tx , and Tx of melt-spun and Pd-coated Ni60 Nb30 Ta10 amorphous alloy membrane before and after permeation test Condition
Tg (◦ C)
Tx onset (◦ C)
Tx (◦ C)
Melt-spun Before hydrogen permeation After hydrogen permeation
648 647 641
664 664 664
16 17 23
In this study we have examined the hydrogen permeability of the Pd-coated melt-spun Ni60 Nb30 Ta10 amorphous alloy membrane in the temperature range of 573–673 K up to a pressure of 0.6 MPa. The maximum permeability of Pd-coated Ni60 Nb30 Ta10 amorphous alloy membrane was 4.13 × 10−8 mol/m s Pa1/2 at 673 K, which is approximately twice the permeability of Pd60 Cu40 alloy. Owing to the high glass transition temperature and resistance to hydrogen embrittlement Ni60 Nb30 Ta10 amorphous alloy was not broken after permeation test in the range of 573–673 K. After permeation test, the crystallization temperature, Tx of Ni60 Nb30 Ta10 was not changed, but the supercooled liquid region, Tx was slightly increased. However, a palladium hydride phase was observed by XRD analysis. Acknowledgements
The as-melt-spun and Pd-coated Ni60 Nb30 Ta10 amorphous alloy membranes before and after permeation test were analyzed using DSC and XRD. The Tg , Tx , and Tx of as-melt-spun and Pd-coated Ni60 Nb30 Ta10 amorphous alloy membranes before and after permeation test was measured from the DSC curves shown in Fig. 3 and are requested in Table 1. After hydrogen permeation, the crystallization temperature, Tx did not changed but the glass transition temperature, Tg was slightly shifted towards lower temperature. So the supercooled liquid region Tx enhanced because the density of amorphous alloy could be increased due to the hydrogenation after hydrogen permeation.
Fig. 4. XRD patterns of the melt-spun and Pd-coated Ni60 Nb30 Ta10 amorphous alloy membrane before and after permeation test.
The authors thank the KIST Research Program, New & Renewable Energy Center, and Center for Nanostructured Materials Technology for providing the financial support for this research under contract nos. KIST 2E19470, 2005-N-CO02-P02-0-000, and 05K1501-00410, respectively, and D.H. Kim also wish to express his appreciation for the financial support provided by the Creative Research Initiatives of the Korean Ministry of Science and Technology. References [1] R. Farrauto, S. Hwang, L. Shore, W. Ruettinger, J. Lampert, T. Giroux, Y. Liu, O. Ilinich, Annu. Rev. Mater. Res. 33 (2003) 1–27. [2] Y.D. Park, B. Mishra, Met. Mater. Int. 11 (2005) 241–248. [3] K. Hashi, K. Ishikawa, T. Matsuda, K. Aoki, J. Alloys Compd. 368 (2004) 215–220. [4] K. Aoki, Mater. Sci. Eng. A 304–306 (2001) 45–53. [5] T. Takano, K. Ishikawa, T. Matsuda, K. Aoki, Mater. Trans. 45 (2004) 3360–3362. [6] B.D. Morreale, M.V. Ciocco, B.H. Howard, R.P. Killmeyer, A.V. Cugini, R.M. Enick, J. Membr. Sci. 241 (2004) 219–224. [7] T. Takahashi, M. Inoue, T. Kai, Appl. Catal. A: Gen. 218 (2001) 189– 195. [8] S. Hara, N. Hatakeyama, N. Itoh, H.M. Kimura, A. Inoue, J. Membr. Sci. 211 (2003) 149–156. [9] J. Flis, S. Ashok, N.S. Stoloff, D.J. Duquette, Acta Metall. 35 (1987) 2071–2079. [10] S. Jayalakshmi, K.B. Kim, E. Fleury, J. Alloys Compd. 417 (2006) 195–202. [11] W. Chiang, W. Yeh, J. Wu, Mater. Lett. 59 (2005) 2542–2544. [12] S. Yamaura, S. Nakata, H. Kimura, Y. Shimpo, M. Nishida, A. Inoue, Mater. Trans. 46 (2005) 1768–1770.
Hydrogen permeation properties of Pd-coated Ni60Nb30Ta10 amorphous alloy membrane K.B. Kim a,∗ , K.D. Kim a,b , D.Y. Lee a , Y.C. Kim a , E. Fleury a , D.H. Kim b a
Advanced Materials Research Center, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650, South Korea b Department of Metallurgical Engineering, Center for Non-crystalline Materials, Yonsei University, Seoul 120-749, South Korea Received 25 August 2005; received in revised form 20 February 2006; accepted 1 March 2006
Abstract The hydrogen permeability of a melt-spun Ni60 Nb30 Ta10 (numbers indicate at.%) amorphous alloy has been examined in the temperature range of 573–673 K and pressures up to 0.6 MPa. Pd60 Cu40 alloy membranes were also evaluated in the same manner. The permeated hydrogen flux was increased with increasing the temperature and the difference of hydrogen pressure between the feed side and permeate side of the membrane. The maximum hydrogen permeability of the Ni60 Nb30 Ta10 glassy alloy was 4.13 × 10−8 mol/m s Pa1/2 at 673 K, which was almost twice the permeability of Pd60 Cu40 alloy measured under the same conditions. These permeation characteristics imply the possibility of future practical application of the glassy alloys as the hydrogen separation membrane. © 2006 Elsevier B.V. All rights reserved. Keywords: Hydrogen permeation; Hydrogen separation membrane; Ni60 Nb30 Ta10 amorphous alloy; Pd60 Cu40 alloy
1. Introduction Hydrogen production is expected to markedly increase, because high purity hydrogen is required in many applications, for example, as an energy source of fuel cells, semiconductor manufacture and petrochemical industry [1–3]. At present, the most effective method to produce high purity hydrogen uses hydrogen separative membranes [4,5]. Progress in membrane technology has the potential to improve the efficiency of hydrogen separation and to reduce the cost associated with hydrogen production. Palladium and its alloys were first identified as a highly hydrogen permeable material and it is still used for high performance hydrogen separation applications today [6]. The advantages of palladium over other membrane materials are the catalytic surface, high hydrogen permeability, infinite hydrogen selectivity, corrosion resistance, and temperature stability. However, owing to its cost and in order to supply hydrogen at a reduced cost for the coming hydrogen energy society, it is desirable to develop new membrane alloys with minimum addition or absence of Pd metal.
∗
Corresponding author. Tel.: +82 2 958 5454; fax: +82 2 958 5449. E-mail address: [email protected] (K.B. Kim).
0921-5093/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.msea.2006.03.144
Non-Pd-based membrane alloys, such as V-based alloys, have been investigated by many research groups [7,8]. Values of the hydrogen permeation were satisfactory, however the drawback of this alloys are the poor selectivity and the sensibility of hydrogen embrittlement [9,10]. It is well known that amorphous alloys have various excellent characteristics, as for example high strength and high corrosion resistance in comparison with crystalline ones [11,12]. Therefore, the objective of this study is an attempt to develop amorphous alloys as new hydrogen permeation membrane materials. In this paper, we will report the production of amorphous Ni60 Nb30 Ta10 (numbers indicate at.%) alloy by the melt-spinning method and we will examine the hydrogen permeability between 573 and 673 K for a pressure up to 0.6 MPa. 2. Experimental Ni60 Nb30 Ta10 and Pd60 Cu40 alloy ingots were prepared by arc-melting pure metals in an argon atmosphere. Melt-spun ribbons were produced by the single roller melt-spinning technique in an argon atmosphere. The Ni60 Nb30 Ta10 ribbon was about 6 mm wide and 70 m thick, and the Pd60 Cu40 ribbon was about 10 mm wide and around 30 m thick. The amorphicity of the melt-spun Ni60 Nb30 Ta10 ribbon was investigated by Xray diffractometry.
K.B. Kim et al. / Materials Science and Engineering A 449–451 (2007) 934–936
Palladium thin film of about 60 nm in thickness was deposited on both sides of specimens by a sputtering technique as an active catalyst for hydrogen dissociation and recombination during permeation. Hydrogen permeation measurements were performed with a conventional gas-permeation technique in the temperature range of 573–673 K, at the hydrogen pressure up to 0.6 MPa. Membrane specimens were mounted in the gas-permeation cell. The permeation area was about 25 mm2 . A pure hydrogen gas was introduced to one side (feed side) of the membrane and then the flow rate of effluent hydrogen gas from the other side (permeate side) was measured by the flow meter. After evacuating by means of a rotary pump, pure helium gas was first introduced for purge, and the specimen membranes were heated up to a given test temperature in a helium atmosphere by an electrical furnace. Then, the evacuation by a rotary pump and the subsequent introduction of a pure hydrogen gas were repeated to eliminate the atmospherical contamination from the permeation cell. Also, an activation treatment was done by exposing hydrogen gas both sides of the membrane to a pressure of 0.2 MPa for 1 h at the test temperature before measuring the hydrogen permeation rate. 3. Results and discussion The hydrogen permeability of Ni60 Nb30 Ta10 amorphous alloy was measured up to 673 K under a hydrogen pressure at a feed side of the membrane of 0.6 MPa. The hydrogen permeation rate was measured as a function of the difference of hydrogen pressure between the feed side and the permeate side of the membrane as shown in Fig. 1. The variation of the hydrogen flux was found to increase proportionally with the square roots of the pressure difference between the feed side and permeate side of the membrane. Also it is worth noticing that Ni60 Nb30 Ta10 amorphous alloy was not broken after permeation test in the range of 573–673 K, which can be explained by the glass transition temperature of this alloy significantly larger than the testing temperature and the resistance to hydrogen embrittlement.
Fig. 2. Arrhenius plot of the hydrogen permeability of a melt-spun Ni60 Nb30 Ta10 glassy alloy and Pd60 Cu40 alloy as a function of inversed temperature.
Fig. 2 shows the hydrogen permeability of the Ni60 Nb30 Ta10 amorphous alloy membrane as a function of the inverse temperature. The permeation data of the Pd60 Cu40 alloy was also measured under identical condition in order to compare with the hydrogen permeability of Ni60 Nb30 Ta10 amorphous alloy and to check our hydrogen permeation equipment. The hydrogen flux through the Pd60 Cu40 membrane was found to increase up to 673 K and then dropped for further increase of the temperature. In Pd–Cu alloy membrane, a maximum hydrogen permeability of 2.1 × 10−8 mol/m s Pa1/2 at 673 K was measured which is in agreement with published data [6]. The hydrogen flux dropped over 673 K is believed to result from the phase transformation from bcc to mixed fcc and bcc structures. It is well known that owing to its lesser atomic packing, the hydrogen permeation is easier in bcc structure than that of fcc structure. For Ni–Nb–Ta alloy, the hydrogen permeability increases exponentially with increasing temperature. The maximum permeability of Pd-coated Ni60 Nb30 Ta10 amorphous alloy membrane was measured to be 4.13 × 10−8 mol/m s Pa1/2 at 673 K that is almost twice the values of the hydrogen permeability for Pd60 Cu40 alloy. In general, when it is controlled by diffusion of hydrogen atoms in the membrane, hydrogen permeation through a metal membrane is proportional to the square root of hydrogen partial pressure, p1/2 , so that the hydrogen flux (hydrogen permeation rate), J, should be written as follows J=
Fig. 1. Hydrogen flux of melt-spun Ni60 Nb30 Ta10 amorphous alloy as a function of the difference in the square root of hydrogen pressures on both sides of the membrane.
935
P¯ p1/2 d
(1)
where d is the membrane thickness and P¯ is the permeability. Therefore, the permeability as a material constant is not dependent on the membrane thickness and can be compared to the other membrane. But the hydrogen flux, which is very important factor for the production of hydrogen gas, is very dependent on the membrane thickness. In order to produce more the hydrogen gas through a metal membrane it is very important to make the thinner membrane.
936
K.B. Kim et al. / Materials Science and Engineering A 449–451 (2007) 934–936
Fig. 4 shows the XRD patterns of the as-melt-spun and Pdcoated Ni60 Nb30 Ta10 amorphous alloy membranes before and after permeation test. In addition to the halo peak of the amorphous phase, the Pd peaks were observed in the Pd-coated Ni60 Nb30 Ta10 amorphous alloy membrane before permeation test. After hydrogen permeation test, hydride peaks appeared with Pd peaks indicating that some Pd atoms combined with hydrogen atom to form palladium hydride. 4. Summary
Fig. 3. The DSC curves of melt-spun and Pd-coated Ni60 Nb30 Ta10 amorphous alloy membrane before and after permeation test. Table 1 The Tg , Tx , and Tx of melt-spun and Pd-coated Ni60 Nb30 Ta10 amorphous alloy membrane before and after permeation test Condition
Tg (◦ C)
Tx onset (◦ C)
Tx (◦ C)
Melt-spun Before hydrogen permeation After hydrogen permeation
648 647 641
664 664 664
16 17 23
In this study we have examined the hydrogen permeability of the Pd-coated melt-spun Ni60 Nb30 Ta10 amorphous alloy membrane in the temperature range of 573–673 K up to a pressure of 0.6 MPa. The maximum permeability of Pd-coated Ni60 Nb30 Ta10 amorphous alloy membrane was 4.13 × 10−8 mol/m s Pa1/2 at 673 K, which is approximately twice the permeability of Pd60 Cu40 alloy. Owing to the high glass transition temperature and resistance to hydrogen embrittlement Ni60 Nb30 Ta10 amorphous alloy was not broken after permeation test in the range of 573–673 K. After permeation test, the crystallization temperature, Tx of Ni60 Nb30 Ta10 was not changed, but the supercooled liquid region, Tx was slightly increased. However, a palladium hydride phase was observed by XRD analysis. Acknowledgements
The as-melt-spun and Pd-coated Ni60 Nb30 Ta10 amorphous alloy membranes before and after permeation test were analyzed using DSC and XRD. The Tg , Tx , and Tx of as-melt-spun and Pd-coated Ni60 Nb30 Ta10 amorphous alloy membranes before and after permeation test was measured from the DSC curves shown in Fig. 3 and are requested in Table 1. After hydrogen permeation, the crystallization temperature, Tx did not changed but the glass transition temperature, Tg was slightly shifted towards lower temperature. So the supercooled liquid region Tx enhanced because the density of amorphous alloy could be increased due to the hydrogenation after hydrogen permeation.
Fig. 4. XRD patterns of the melt-spun and Pd-coated Ni60 Nb30 Ta10 amorphous alloy membrane before and after permeation test.
The authors thank the KIST Research Program, New & Renewable Energy Center, and Center for Nanostructured Materials Technology for providing the financial support for this research under contract nos. KIST 2E19470, 2005-N-CO02-P02-0-000, and 05K1501-00410, respectively, and D.H. Kim also wish to express his appreciation for the financial support provided by the Creative Research Initiatives of the Korean Ministry of Science and Technology. References [1] R. Farrauto, S. Hwang, L. Shore, W. Ruettinger, J. Lampert, T. Giroux, Y. Liu, O. Ilinich, Annu. Rev. Mater. Res. 33 (2003) 1–27. [2] Y.D. Park, B. Mishra, Met. Mater. Int. 11 (2005) 241–248. [3] K. Hashi, K. Ishikawa, T. Matsuda, K. Aoki, J. Alloys Compd. 368 (2004) 215–220. [4] K. Aoki, Mater. Sci. Eng. A 304–306 (2001) 45–53. [5] T. Takano, K. Ishikawa, T. Matsuda, K. Aoki, Mater. Trans. 45 (2004) 3360–3362. [6] B.D. Morreale, M.V. Ciocco, B.H. Howard, R.P. Killmeyer, A.V. Cugini, R.M. Enick, J. Membr. Sci. 241 (2004) 219–224. [7] T. Takahashi, M. Inoue, T. Kai, Appl. Catal. A: Gen. 218 (2001) 189– 195. [8] S. Hara, N. Hatakeyama, N. Itoh, H.M. Kimura, A. Inoue, J. Membr. Sci. 211 (2003) 149–156. [9] J. Flis, S. Ashok, N.S. Stoloff, D.J. Duquette, Acta Metall. 35 (1987) 2071–2079. [10] S. Jayalakshmi, K.B. Kim, E. Fleury, J. Alloys Compd. 417 (2006) 195–202. [11] W. Chiang, W. Yeh, J. Wu, Mater. Lett. 59 (2005) 2542–2544. [12] S. Yamaura, S. Nakata, H. Kimura, Y. Shimpo, M. Nishida, A. Inoue, Mater. Trans. 46 (2005) 1768–1770.