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Phase transformation and heating behaviors of iron-based ceramic powders in a single-mode microwave applicator
Journal of Alloys and Compounds 476 (2009) 482–485
Contents lists available at ScienceDirect
Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom
Phase transformation and heating behaviors of iron-based ceramic powders in a single-mode microwave applicator Song Li a,∗ , Guoqiang Xie a , Dmitri V. Louzguine-Luzgin a,b , Ziping Cao c , Noboru Yoshikawa c , Motoyasu Sato d , Akihisa Inoue a,b a
Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan Graduate School of Environmental Studies, Tohoku University, Sendai 980-8577, Japan d National Institute for Fusion Science, Toki 509-5292, Japan b c
a r t i c l e
i n f o
Article history: Received 23 July 2008 Received in revised form 1 September 2008 Accepted 5 September 2008 Available online 5 November 2008 Keywords: Phase transformation Microwave heating Decomposition
a b s t r a c t The application of microwave radiation for heating iron-based ceramic and elemental blend powders was performed in a single-mode microwave applicator. The heating behaviors and phase transformations of these powders by microwave radiation in a separated electric-field and magnetic-field were investigated. These powders could be heated up more easily in a magnetic-field than in electric-field. Microwave heating of iron and iron boride blend powders induced the formation of Fe2 B and Fe3 B phases. The phenomenon of decomposition was confirmed and only ␣-Fe phase could be observed after microwave heating of Fe3 C powder both in an electric- and magnetic-fields. © 2008 Elsevier B.V. All rights reserved.
1. Introduction Microwave (MW) heating has attracted increasing interest as a novel method in the field of material processing as it offers significant advantages such as direct volumetric heating, significant energy savings, reduction in processing time, uniform microstructure of materials and lower environmental hazards, many of which stem from the unique nature of the energy transfer. Over the past 60 years, microwave heating of a variety of materials, ranging from rubber, wood, bacon, and polymers to semiconductors, ceramics and metal powders, has been studied extensively from the perspectives of synthesis, heating, sintering, and microstructure revolution [1–6], including sintering and joining of ceramics, heating and sintering of semiconductors, the preparation of oxides, nitrides and chalcogenides, and the formation of nanomaterials and glassy phases. Some interesting phenomena and useful properties have been observed in microwave heating of these materials. More recently, microwave heating has been found to induce the de-crystallization of ferrite and some other materials [7,8], while the crystallization of silicate glasses enhanced by microwave heating has also been reported [9]. These special heating effects have impelled us to investigate the effects of microwave
∗ Corresponding author. E-mail address: [email protected] (S. Li). 0925-8388/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2008.09.046
heating on various materials, especially metal and ceramic materials. Amorphous and microcrystalline iron boride alloys are a basis of many widely used magnetic alloys and have been most completely studied over a wide range of iron boride compositions (2–50 at.% boride) [10]. Iron boride, Fe2 B and Fe3 B phases are also well known for their high hardness and interesting magnetic properties. So it is interesting to use microwave radiation as a heating resource to investigate phase transformation of iron boride alloy powders at high temperature. In the present work, as boride has a relatively high melting point, mixture of iron and iron boride powders was used as starting materials. For comparison, Fe3 C powders were also used for microwave heating. These powders were heated up to their sub-melting temperatures (about 200 ◦ C lower than their melting temperatures). Microwave radiation was applied for the heating of these powders in a separated electric-field (E-field) and magneticfield (H-field) using a single-mode 2.45 GHz MW applicator, and the effects of MW radiation on their microstructure evolutions and heating behaviors were investigated. 2. Experimental Mixtures of elemental iron and iron boride powders of four nominal compositions (Fe80 B20 , Fe70 B30 , Fe65 B35 and Fe60 B40 ) were obtained by powder mixing for 24 h in a mixer. The purity of iron and iron boride was 99.9%. The mean size of iron and iron boride particles was about 40 m. The purity of Fe3 C was 99.5% and its mean particle size was about 60 m. The structures of the original pow-
S. Li et al. / Journal of Alloys and Compounds 476 (2009) 482–485
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Fig. 1. (a) Heating curves of FeB powder heated by MW in the E- and H-fields; (b) XRD patterns of FeB powder heated by MW in the E- and H-fields.
ders and the heated specimens in the MW field were examined by X-ray diffraction (XRD). A single-mode microwave applicator (Nikoha MKN-152-359, max 1.5 kW, Yokohama, Japan) was used for an E-field or H-field separation heating. The powders were enclosed in a holder made of silica glass with the dimensions of 5 mm in diameter and 7 mm in height and heated at a constant input power ranging from 200 to 1500 W. The adiabatic material like Kaowool blanket was placed around the holder. These powders were placed in a position of either E-field or H-field maximum in the wave guide applicator, heated by microwave energy absorption up to appointed temperatures. Temperature measurement of the microwave-heating specimens was performed with an optical method (PhotoriX System, Luxtron, Santa Clara, CA, USA), using a sapphire rod for the light guide. In this method, it is not possible to measure the specimen temperature below 623 K. The adjustment of the temperature was done by controlling the three stubs to minimize the reflected power (Pr ), while the input power (Pf ) was kept constant. All experiments were carried out in a flowing nitrogen gas to avoid oxidation of metal samples at high temperature.
3. Results and discussion Fig. 1 shows the heating curves and XRD patterns of iron boride powder heated by MW in the E- and H-fields. As seen in Fig. 1(a), both heating curves are not smooth as the heating process was performed by manipulating the three stubs manually. It can be also found that iron boride particles are heated up more easily in the Hfield than in the E-field. The XRD patterns show that the diffraction peaks corresponding to FeB phase have not been changed via MW heating. Fig. 2 presents the heating curves of Fe60 B40 , Fe65 B35 , Fe70 B30 and Fe80 B20 blend powders heated by MW in the E-field. The heating processes are associated with sparking and bulk sintered bodies can be formed. As shown in Fig. 2(a), the addition of iron powder
makes it possible to heat iron boride powder to higher temperature. Compared with other blend powders, Fe80 B20 blend powder is heated up more difficultly in the E-field, indicating that the heating abilities of these blend powders depend on the content of iron powder and more efficient heating only occurs at a sufficient content of iron powder. It can be found from the heating curves in Fig. 2(b) that the anomalous heating rates have occurred in Fe60 B40 , Fe65 B35 and Fe70 B30 blend powders, and the maximum can attain 7500 ◦ C/s. Fig. 3 shows the XRD patterns of Fe60 B40 , Fe65 B35 and Fe70 B30 blend powders heated above 1000 ◦ C by MW in the E-field. As shown in Fig. 3, the formation of equilibrium Fe2 B phase can be found in the XRD patterns of all bulk sintered specimens. Some diffraction peaks corresponding to FeB phase have still been detected in the Fe60 B40 sintered specimen, while Fe phase was found in the Fe70 B30 sintered specimen. For the Fe65 B35 sintered specimen, the diffraction peaks corresponding to Fe and FeB phase have disappeared completely and only Fe2 B phase could be detected. This means that microwave heating has induced phase transformation of Fe60 B40 , Fe65 B35 and Fe70 B30 blend powders in the E-field. The phase transformation of iron and iron boride blend powders was also observed in the H-field. Fig. 4 shows the heating curves and XRD patterns of Fe70 B30 blend powder heated by MW. As seen in Fig. 4(a), though Fe70 B30 blend powder can be heated up in both E- and H-fields, the heat response is more quick in the H-field than in the E-field. The XRD patterns in Fig. 4(b) show that phase transformation has taken place in Fe70 B30 blend powder heated by MW. Different from in the E-field, the formation of Fe3 B phase has been detected in the samples heated in the H-field.
Fig. 2. (a) Heating curves of Fe60 B40 , Fe65 B35 , Fe70 B30 and Fe80 B40 blend powders heated by microwave in the E-field; (b) enhanced heating rates of Fe60 B40 , Fe65 B35 and Fe70 B30 blend powders in the E-field.
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Fig. 3. XRD patterns of Fe60 B40 , Fe65 B35 and Fe70 B30 blend powders heated up more than 1000 ◦ C by microwave in the E-field.
Fig. 5 shows the XRD patterns and heating curves of Fe3 C powder heated by MW. The heating curves (seen in Fig. 5(a)) are similar to the above mentioned curves. Compared with iron boride, Fe3 C particles are easier to couple with microwaves and heated up to higher temperature. As shown in Fig. 5(b), with increasing temperature microwave induces the decomposition of Fe3 C phase and only ␣-Fe phase can be observed in the samples heated both in the Eand H-field. Microwave heating is based on the capacity of a material to absorb the electromagnetic energy. This capacity is closely linked with the electrical conductivity, complex permittivity, and complex permeability of a material [1,6]. For iron, iron boride and Fe3 C powders, magnetic loss is also important in the interaction of microwave and these powders besides eddy current loss. In the H-field, magnetic loss is active under the Curie point and these particles couple with microwave more quickly. This can interpret why microwave heating of these particles is faster and more efficient in the H-field than in the E-field. The anomalous heating rates have been observed for two phase iron–iron boride blend powders in a microwave field. According to the microwave effect [11], the difference in the absorption factors of iron and iron boride powders may cause the temperature gradient between the particles to be high which leads to enhanced reaction rates in an E-field. Otherwise, the enhanced diffusion rates between iron and iron boride particles induced by microwave are also considered to be responsible for the anomalous heating rates [12]. Microwave heating has induced phase transformation of iron and iron boride blend powders. As above referred to, microwave heating can enhance the diffusion between iron and iron boride particles, this leading to the formation of Fe2 B and Fe3 B phases. For the Fe70 B30 specimen, the difference of phase compositions reflects the difference of diffusion rates between the E- and H-fields. This means that microwave can enhance diffusion rates of iron and iron boride particles more efficient in the H-field.
Fig. 4. Heating curves of Fe70 B30 blend powder heated by MW in the E- and H-fields; (b) XRD patterns of Fe70 B30 blend powder heated by MW in the E- and H-fields.
Fig. 5. (a) Heating curves of Fe3 C powder heated by MW in the E- and H-fields; (b) XRD patterns of Fe3 C powder heated by MW in the E- and H-fields.
S. Li et al. / Journal of Alloys and Compounds 476 (2009) 482–485
4. Conclusion Microwave heating of iron boride, Fe3 C and mixtures of Fe and iron boride powder was performed in the separated E- and H-fields. These powders were more easily heated up by microwave in the Hfield than E-field. Microwave heating of iron boride powder under its sub-melting temperature did not induce phase transformation. The Fe2 B phase was obtained by microwave heating of mixtures of Fe and iron boride powders in the E-field. Fe and iron boride phases disappeared completely and bulk Fe2 B intermetallic compound was obtained after Fe65 B35 blend powder was heated up to about 1200 ◦ C by microwave. In the H-field microwave heating of Fe70 B30 blend powder induced the formation of Fe3 B phase. The phenomenon of decomposition was found by MW heating of Fe3 C powder above 1000 ◦ C both in the E- and H-fields. Only ␣-Fe phase could be observed. Acknowledgements The work was supported by a Grant-In-Aid for Science Research in a Priority Area on “Science and Technology of MicrowaveInduced, thermally Non-Equilibrium Reaction” (No. 18070001) as
485
well as by Grant-In-Aid on “Research and Development Project on Advanced Metallic Glasses, Inorganic Materials, and Joining Technology” from the Ministry of Education, Sports, Culture, Science and Technology, Japan. References [1] Yu.V. Bykov, K.I. Rybakov, V.E. Semenov, J. Phys. D 34 (2001) R55. [2] R. Roy, D. Agrawal, J. Cheng, S. Gedevanishvili, Nature 399 (1999) 668. [3] D.C. Dube, P.D. Ramesh, J. Cheng, M.T. Lanagan, D. Agrawal, R. Roy, Appl. Phys. Lett. 85 (2004) 3632. [4] R. Peelamedu, R. Roy, D. Agrawal, W. Drawl, J. Mater. Res. 19 (2004) 1599. [5] D.C. Thompson, H.C. Kim, T.L. Alford, J.W. Mayer, Appl. Phys. Lett. 83 (2003) 3918. [6] D.E. Clark, W.H. Sutton, Annu. Rev. Sci. 26 (1996) 299. [7] K. Saitou, Scripta Mater. 54 (2006) 875. [8] R. Roy, R. Peelamedu, L. Hurtt, J.P. Cheng, D. Agrawal, Mater. Res. Innovations 6 (2002) 128. [9] R. Roy, R. Peelamedu, C. Grimes, J.P. Cheng, D. Agrawal, J. Mater. Res. 17 (2002) 3008. [10] F.E. Lyubarskioe (Ed.), Amorphous Metallic Alloys, Metallurgiya, Moscow, 1987 (in Russian). [11] U.R. Kattner, in: T.B. Massalski (Ed.), Binary Alloy Diagrams, American Society for Metals, Metals Park, OH, 1986, p. 180. [12] C. Antonio, R.T. Deam, Chem. Chem. Phys. 9 (2007) 2976.
Contents lists available at ScienceDirect
Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom
Phase transformation and heating behaviors of iron-based ceramic powders in a single-mode microwave applicator Song Li a,∗ , Guoqiang Xie a , Dmitri V. Louzguine-Luzgin a,b , Ziping Cao c , Noboru Yoshikawa c , Motoyasu Sato d , Akihisa Inoue a,b a
Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan Graduate School of Environmental Studies, Tohoku University, Sendai 980-8577, Japan d National Institute for Fusion Science, Toki 509-5292, Japan b c
a r t i c l e
i n f o
Article history: Received 23 July 2008 Received in revised form 1 September 2008 Accepted 5 September 2008 Available online 5 November 2008 Keywords: Phase transformation Microwave heating Decomposition
a b s t r a c t The application of microwave radiation for heating iron-based ceramic and elemental blend powders was performed in a single-mode microwave applicator. The heating behaviors and phase transformations of these powders by microwave radiation in a separated electric-field and magnetic-field were investigated. These powders could be heated up more easily in a magnetic-field than in electric-field. Microwave heating of iron and iron boride blend powders induced the formation of Fe2 B and Fe3 B phases. The phenomenon of decomposition was confirmed and only ␣-Fe phase could be observed after microwave heating of Fe3 C powder both in an electric- and magnetic-fields. © 2008 Elsevier B.V. All rights reserved.
1. Introduction Microwave (MW) heating has attracted increasing interest as a novel method in the field of material processing as it offers significant advantages such as direct volumetric heating, significant energy savings, reduction in processing time, uniform microstructure of materials and lower environmental hazards, many of which stem from the unique nature of the energy transfer. Over the past 60 years, microwave heating of a variety of materials, ranging from rubber, wood, bacon, and polymers to semiconductors, ceramics and metal powders, has been studied extensively from the perspectives of synthesis, heating, sintering, and microstructure revolution [1–6], including sintering and joining of ceramics, heating and sintering of semiconductors, the preparation of oxides, nitrides and chalcogenides, and the formation of nanomaterials and glassy phases. Some interesting phenomena and useful properties have been observed in microwave heating of these materials. More recently, microwave heating has been found to induce the de-crystallization of ferrite and some other materials [7,8], while the crystallization of silicate glasses enhanced by microwave heating has also been reported [9]. These special heating effects have impelled us to investigate the effects of microwave
∗ Corresponding author. E-mail address: [email protected] (S. Li). 0925-8388/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2008.09.046
heating on various materials, especially metal and ceramic materials. Amorphous and microcrystalline iron boride alloys are a basis of many widely used magnetic alloys and have been most completely studied over a wide range of iron boride compositions (2–50 at.% boride) [10]. Iron boride, Fe2 B and Fe3 B phases are also well known for their high hardness and interesting magnetic properties. So it is interesting to use microwave radiation as a heating resource to investigate phase transformation of iron boride alloy powders at high temperature. In the present work, as boride has a relatively high melting point, mixture of iron and iron boride powders was used as starting materials. For comparison, Fe3 C powders were also used for microwave heating. These powders were heated up to their sub-melting temperatures (about 200 ◦ C lower than their melting temperatures). Microwave radiation was applied for the heating of these powders in a separated electric-field (E-field) and magneticfield (H-field) using a single-mode 2.45 GHz MW applicator, and the effects of MW radiation on their microstructure evolutions and heating behaviors were investigated. 2. Experimental Mixtures of elemental iron and iron boride powders of four nominal compositions (Fe80 B20 , Fe70 B30 , Fe65 B35 and Fe60 B40 ) were obtained by powder mixing for 24 h in a mixer. The purity of iron and iron boride was 99.9%. The mean size of iron and iron boride particles was about 40 m. The purity of Fe3 C was 99.5% and its mean particle size was about 60 m. The structures of the original pow-
S. Li et al. / Journal of Alloys and Compounds 476 (2009) 482–485
483
Fig. 1. (a) Heating curves of FeB powder heated by MW in the E- and H-fields; (b) XRD patterns of FeB powder heated by MW in the E- and H-fields.
ders and the heated specimens in the MW field were examined by X-ray diffraction (XRD). A single-mode microwave applicator (Nikoha MKN-152-359, max 1.5 kW, Yokohama, Japan) was used for an E-field or H-field separation heating. The powders were enclosed in a holder made of silica glass with the dimensions of 5 mm in diameter and 7 mm in height and heated at a constant input power ranging from 200 to 1500 W. The adiabatic material like Kaowool blanket was placed around the holder. These powders were placed in a position of either E-field or H-field maximum in the wave guide applicator, heated by microwave energy absorption up to appointed temperatures. Temperature measurement of the microwave-heating specimens was performed with an optical method (PhotoriX System, Luxtron, Santa Clara, CA, USA), using a sapphire rod for the light guide. In this method, it is not possible to measure the specimen temperature below 623 K. The adjustment of the temperature was done by controlling the three stubs to minimize the reflected power (Pr ), while the input power (Pf ) was kept constant. All experiments were carried out in a flowing nitrogen gas to avoid oxidation of metal samples at high temperature.
3. Results and discussion Fig. 1 shows the heating curves and XRD patterns of iron boride powder heated by MW in the E- and H-fields. As seen in Fig. 1(a), both heating curves are not smooth as the heating process was performed by manipulating the three stubs manually. It can be also found that iron boride particles are heated up more easily in the Hfield than in the E-field. The XRD patterns show that the diffraction peaks corresponding to FeB phase have not been changed via MW heating. Fig. 2 presents the heating curves of Fe60 B40 , Fe65 B35 , Fe70 B30 and Fe80 B20 blend powders heated by MW in the E-field. The heating processes are associated with sparking and bulk sintered bodies can be formed. As shown in Fig. 2(a), the addition of iron powder
makes it possible to heat iron boride powder to higher temperature. Compared with other blend powders, Fe80 B20 blend powder is heated up more difficultly in the E-field, indicating that the heating abilities of these blend powders depend on the content of iron powder and more efficient heating only occurs at a sufficient content of iron powder. It can be found from the heating curves in Fig. 2(b) that the anomalous heating rates have occurred in Fe60 B40 , Fe65 B35 and Fe70 B30 blend powders, and the maximum can attain 7500 ◦ C/s. Fig. 3 shows the XRD patterns of Fe60 B40 , Fe65 B35 and Fe70 B30 blend powders heated above 1000 ◦ C by MW in the E-field. As shown in Fig. 3, the formation of equilibrium Fe2 B phase can be found in the XRD patterns of all bulk sintered specimens. Some diffraction peaks corresponding to FeB phase have still been detected in the Fe60 B40 sintered specimen, while Fe phase was found in the Fe70 B30 sintered specimen. For the Fe65 B35 sintered specimen, the diffraction peaks corresponding to Fe and FeB phase have disappeared completely and only Fe2 B phase could be detected. This means that microwave heating has induced phase transformation of Fe60 B40 , Fe65 B35 and Fe70 B30 blend powders in the E-field. The phase transformation of iron and iron boride blend powders was also observed in the H-field. Fig. 4 shows the heating curves and XRD patterns of Fe70 B30 blend powder heated by MW. As seen in Fig. 4(a), though Fe70 B30 blend powder can be heated up in both E- and H-fields, the heat response is more quick in the H-field than in the E-field. The XRD patterns in Fig. 4(b) show that phase transformation has taken place in Fe70 B30 blend powder heated by MW. Different from in the E-field, the formation of Fe3 B phase has been detected in the samples heated in the H-field.
Fig. 2. (a) Heating curves of Fe60 B40 , Fe65 B35 , Fe70 B30 and Fe80 B40 blend powders heated by microwave in the E-field; (b) enhanced heating rates of Fe60 B40 , Fe65 B35 and Fe70 B30 blend powders in the E-field.
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Fig. 3. XRD patterns of Fe60 B40 , Fe65 B35 and Fe70 B30 blend powders heated up more than 1000 ◦ C by microwave in the E-field.
Fig. 5 shows the XRD patterns and heating curves of Fe3 C powder heated by MW. The heating curves (seen in Fig. 5(a)) are similar to the above mentioned curves. Compared with iron boride, Fe3 C particles are easier to couple with microwaves and heated up to higher temperature. As shown in Fig. 5(b), with increasing temperature microwave induces the decomposition of Fe3 C phase and only ␣-Fe phase can be observed in the samples heated both in the Eand H-field. Microwave heating is based on the capacity of a material to absorb the electromagnetic energy. This capacity is closely linked with the electrical conductivity, complex permittivity, and complex permeability of a material [1,6]. For iron, iron boride and Fe3 C powders, magnetic loss is also important in the interaction of microwave and these powders besides eddy current loss. In the H-field, magnetic loss is active under the Curie point and these particles couple with microwave more quickly. This can interpret why microwave heating of these particles is faster and more efficient in the H-field than in the E-field. The anomalous heating rates have been observed for two phase iron–iron boride blend powders in a microwave field. According to the microwave effect [11], the difference in the absorption factors of iron and iron boride powders may cause the temperature gradient between the particles to be high which leads to enhanced reaction rates in an E-field. Otherwise, the enhanced diffusion rates between iron and iron boride particles induced by microwave are also considered to be responsible for the anomalous heating rates [12]. Microwave heating has induced phase transformation of iron and iron boride blend powders. As above referred to, microwave heating can enhance the diffusion between iron and iron boride particles, this leading to the formation of Fe2 B and Fe3 B phases. For the Fe70 B30 specimen, the difference of phase compositions reflects the difference of diffusion rates between the E- and H-fields. This means that microwave can enhance diffusion rates of iron and iron boride particles more efficient in the H-field.
Fig. 4. Heating curves of Fe70 B30 blend powder heated by MW in the E- and H-fields; (b) XRD patterns of Fe70 B30 blend powder heated by MW in the E- and H-fields.
Fig. 5. (a) Heating curves of Fe3 C powder heated by MW in the E- and H-fields; (b) XRD patterns of Fe3 C powder heated by MW in the E- and H-fields.
S. Li et al. / Journal of Alloys and Compounds 476 (2009) 482–485
4. Conclusion Microwave heating of iron boride, Fe3 C and mixtures of Fe and iron boride powder was performed in the separated E- and H-fields. These powders were more easily heated up by microwave in the Hfield than E-field. Microwave heating of iron boride powder under its sub-melting temperature did not induce phase transformation. The Fe2 B phase was obtained by microwave heating of mixtures of Fe and iron boride powders in the E-field. Fe and iron boride phases disappeared completely and bulk Fe2 B intermetallic compound was obtained after Fe65 B35 blend powder was heated up to about 1200 ◦ C by microwave. In the H-field microwave heating of Fe70 B30 blend powder induced the formation of Fe3 B phase. The phenomenon of decomposition was found by MW heating of Fe3 C powder above 1000 ◦ C both in the E- and H-fields. Only ␣-Fe phase could be observed. Acknowledgements The work was supported by a Grant-In-Aid for Science Research in a Priority Area on “Science and Technology of MicrowaveInduced, thermally Non-Equilibrium Reaction” (No. 18070001) as
485
well as by Grant-In-Aid on “Research and Development Project on Advanced Metallic Glasses, Inorganic Materials, and Joining Technology” from the Ministry of Education, Sports, Culture, Science and Technology, Japan. References [1] Yu.V. Bykov, K.I. Rybakov, V.E. Semenov, J. Phys. D 34 (2001) R55. [2] R. Roy, D. Agrawal, J. Cheng, S. Gedevanishvili, Nature 399 (1999) 668. [3] D.C. Dube, P.D. Ramesh, J. Cheng, M.T. Lanagan, D. Agrawal, R. Roy, Appl. Phys. Lett. 85 (2004) 3632. [4] R. Peelamedu, R. Roy, D. Agrawal, W. Drawl, J. Mater. Res. 19 (2004) 1599. [5] D.C. Thompson, H.C. Kim, T.L. Alford, J.W. Mayer, Appl. Phys. Lett. 83 (2003) 3918. [6] D.E. Clark, W.H. Sutton, Annu. Rev. Sci. 26 (1996) 299. [7] K. Saitou, Scripta Mater. 54 (2006) 875. [8] R. Roy, R. Peelamedu, L. Hurtt, J.P. Cheng, D. Agrawal, Mater. Res. Innovations 6 (2002) 128. [9] R. Roy, R. Peelamedu, C. Grimes, J.P. Cheng, D. Agrawal, J. Mater. Res. 17 (2002) 3008. [10] F.E. Lyubarskioe (Ed.), Amorphous Metallic Alloys, Metallurgiya, Moscow, 1987 (in Russian). [11] U.R. Kattner, in: T.B. Massalski (Ed.), Binary Alloy Diagrams, American Society for Metals, Metals Park, OH, 1986, p. 180. [12] C. Antonio, R.T. Deam, Chem. Chem. Phys. 9 (2007) 2976.