- Email: [email protected]
Comparative study of fusion relevant properties of Be12V and Be12Ti
Fusion Engineering and Design 86 (2011) 2454–2457
Contents lists available at ScienceDirect
Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes
Comparative study of fusion relevant properties of Be12 V and Be12 Ti P. Kurinskiy a,∗ , V. Chakin a , A. Moeslang a , R. Rolli b , E. Alves c , L.C. Alves c , N. Franco c , Ch. Dorn d , A.A. Goraieb e a
Karlsruhe Institute of Technology, FZK, IMF I, P.O. Box 3640, 76021 Karlsruhe, Germany Karlsruhe Institute of Technology, FZK, IMF II, P.O. Box 3640, 76021 Karlsruhe, Germany Instituto Tecnologico e Nuclear, 2686-953 Sacavem, Portugal d Brush Wellman Inc., 14710 W. Portage River South Road, Elmore, OH 43416-9502, USA e GVT UG & Co. KG, In der Tasch 4a, 76227 Karlsruhe, Germany b c
a r t i c l e
i n f o
Article history: Available online 26 January 2011 Keywords: Titanium beryllide Vanadium beryllide Beryllium oxide Oxide surface layer
a b s t r a c t Very similar brittle behavior of failure of Be12 Ti and Be12 V cylindrical specimens has been observed after testing under constant loads at 600 and 800 ◦ C. Oxidation in air at 800 ◦ C of both types of beryllide samples was studied. The thickness of oxidized layers before and after annealing tests was evaluated by means of Ion Beam Analysis using Rutherford backscattering technique. X-ray diffraction analysis revealed the formation of beryllium oxide layer on the surface of Be12 Ti and Be12 V samples. Some quantity of vanadium oxide V2 O5 on the surface of airannealed vanadium beryllide sample related to a presence of vanadium-rich zones in initial material. © 2011 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Since titanium beryllide Be12 Ti and vanadium beryllide Be12 V are considered to be advanced materials for the use as neutron multipliers in the solid breeding blanket [1,2], the proper investigation of their mechanical properties and resistance to oxidation at elevated temperatures is needed. The materials of neutron multiplier are subjected to thermal stresses at temperatures of about 700–750 ◦ C during the operation of the breeding blanket in DEMO reactor and, therefore, the study of mechanical properties has been identified as one of the key issues for the blanket design [3,4]. Gas release characteristics of neutron multiplier are strongly influenced by the presence of oxide layer on the surface of beryllium-based materials. It is known that the diffusivity and solubility of hydrogen isotopes (e.g., tritium) is much smaller in BeO than in pure beryllium, so that, the thickness of the oxide film plays an important role in the ability of berylliumcontaining materials to accumulate and to release radiogenic gases [5–7].
2.1. Materials
∗ Corresponding author. Tel.: +49 7247 82 2908; fax: +49 7247 82 4567. E-mail addresses: [email protected], [email protected] (P. Kurinskiy). 0920-3796/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.fusengdes.2010.12.065
This work was performed using Be12 Ti and Be12 V intermetallic compounds delivered by Company Brush Wellman, Inc., USA. 2.2. Specimens and procedure of constant-load compression tests Cylindrical specimens having 3 mm diameter and 3.5 mm height were cut out of Be12 Ti and Be12 V bars using ultrasonic drilling device. Constant-load compression tests were performed in the closed glove-box system in Hot Cells (Fusion Materials Laboratory) at room temperature, 600 and 800 ◦ C. The test box was constantly purged with nitrogen in order to avoid the oxidation of specimens during the experiment. Constant load of 1000 N was applied uniaxially by means of ceramic plunger with the duration of 100 h for all tested specimens. One should note that this value of the compression force was maximal permissible in the glove-box. Due to a relatively high deviation of the displacement data of the plunger at elevated temperatures, the absolute deformation of cylindrical specimens was measured by extracting of the height values of samples after testing from the known initial height (3.5 mm). Having known diameter of the tested cylinders which is 3 mm and the compression load (1000 N), one can estimate the value of the compression stress in this experiment which is about 140 MPa.
P. Kurinskiy et al. / Fusion Engineering and Design 86 (2011) 2454–2457
Fig. 1. Be12 V specimen after compression testing at 800 ◦ C.
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Fig. 2. Be12 Ti cylindrical sample after loading at 800 ◦ C.
2.3. Investigation of oxidized layers The surface composition of Be12 Ti and Be12 V specimens was investigated at Institute of Nuclear Technologies (ITN) in Sacavem, Portugal. The thickness of the oxidized layers was evaluated on the beryllide specimens in as-received state and after annealing tests in a quartz tube in the electric resistance furnace 800 ◦ C for 1 h in the ambient atmosphere. The thickness of oxide layers on Be12 Ti and Be12 V specimens was investigated by means of Ion Beam Analysis using Rutherford Backscattering (RBS) technique. Particle-induced X-ray emission (PIXE) technique was used to analyze elemental distribution of alloying elements after annealing test in air. 1.6 MeV He+ and 2.0 MeV H+ focused microbeams (size 3 m × 4 m) were used during the surface study of beryllide specimens. 2.4. X-ray diffraction analysis
Fig. 3. RBS spectra of Be12 Ti specimen in as-received state.
Phase composition of as-received and annealed beryllide samples was measured by means of Bruker AXS D8 diffractometer in High Temperature Materials Laboratory, Ma3T, at ITN. 2 range from 10◦ to 90◦ with a step size of 0.02◦ and acquisition time of 1.5 s was used. 3. Results and discussion 3.1. Analysis of mechanical properties after compression tests No measurable deformation and visible cracks have been revealed after constant-load compression tests of both – Be12 Ti and Be12 V cylinders after loading at room temperature. Testing at 600 ◦ C showed that the specimens had some cracks which were parallel to the direction of the applied force and the values of absolute deformation for both beryllides were in the range of only few microns. Testing at 800 ◦ C showed the failure of Be12 Ti and Be12 V cylindrical samples: Be12 V specimen has been broken into some pieces apart (Fig. 1) and Be12 Ti has lost a big fragment (Fig. 2). Thus, both types of beryllides showed very similar brittle behavior of failure. 3.2. Evaluation of the surface of beryllide samples Evaluation of 1.6 MeV He+ RBS spectra obtained from the surface of as-received Be12 Ti (Fig. 3) and Be12 V (Fig. 4) specimens revealed that the oxidized surface layer was about 50 and 30–40 nm, accordingly. Some carbon contamination detected on the surface of Be12 Ti sample probably relates to a material handling.
Fig. 4. RBS spectra of initial Be12 V sample.
After annealing tests at 800 ◦ C for 1 h in air the surface of Be12 Ti sample changed to more tarnished colour and the surface of Be12 V specimen became two-coloured – the inclusions having metallic colour contrasted with a light-brown field. The results depicting the growth of the thickness of the oxidized layer on the surface of Be12 Ti and Be12 V after annealing at 800 ◦ C for 1 h in ambient atmosphere are shown in Fig. 5. The oxygen peak corresponding to Be12 V is broader than the same peak of Be12 Ti sample. Evaluation of RBS spectra of both beryllide specimens showed that Be12 V reacted with oxygen more intensively and the thick-
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P. Kurinskiy et al. / Fusion Engineering and Design 86 (2011) 2454–2457
Fig. 7. V and Be 530 m × 530 m).
elemental
distribution
maps
(scanned
surface
area
Fig. 5. RBS spectra of Be12 Ti and Be12 V samples annealed at 800 ◦ C in air.
Fig. 6. Ti and Be elemental distribution (scanned surface area 530 m × 530 m).
ness of oxidized layer is about 0.7 m. In the case of Be12 Ti sample, the oxygen-enriched layer was estimated to be around 0.3 m. The thickness of the oxidized layers on the surfaces of beryllide samples was evaluated by DAN32 software package. It is notable that the surface area of scanning with the size of approximately 0.2–0.3 mm2 was chosen during Ion Beam Analysis for all investigated specimens, so that different RBS spectra reflect only the average values of the thickness of oxidized layers. Character of distribution of alloying elements (Be, Ti and V) after annealing tests in air was investigated by means of PIXE and RBS. 2.0 MeV H+ beam focused down to a spot with size of 3 m × 4 m has been used during the scanning of the selected surface area (530 m × 530 m) of beryllide specimens. In the case of Be12 Ti specimen, homogeneous distribution of Be and Ti was observed indicating that Be- or Ti-depleted regions were absent on the surface (Fig. 6). V-depleted zones were observed after scanning of the surface of Be12 V sample. Contrasting regions which have the sizes up to hundreds of microns with different contents of V were detected (Fig. 7). Data obtained from the annealed Be12 V specimen showed that oxidized layer can have different stoichiometric contents depending on the surface region. 3.3. X-ray study of annealed beryllide specimens The results of X-ray diffraction analysis showed the presence of Be12 Ti and BeO on the surface of Be12 Ti air-annealed specimen (Fig. 8). High background in a low-angle 2 region could refer to a formation of amorphous layer or big amount of oxide particles with sizes of several nm which have certain influence on X-ray measurements. X-ray diffraction curve (Fig. 9) of Be12 V sample after annealing at 800 ◦ C in air depicts the evident presence of three phases – Be12 V,
Fig. 8. X-ray diffraction pattern of Be12 Ti specimen annealed at 800 ◦ C in air.
Fig. 9. X-ray diffraction pattern of Be12 V specimen after annealing test.
BeO and V2 O5. It is notable that the surface of Be12 V specimen seems to have fully crystalline state compared to Be12 Ti sample annealed at 800 ◦ C. Since the values of oxygen affinity for Be are higher than for Ti and V, the formation of BeO layer will be preferable from the point of view of thermodynamics in the case of oxidation of both kinds of beryllides – Be12 Ti and Be12 V. Beryllium reduces the oxides of titanium and vanadium during interaction with air at elevated temperatures and, thus, oxidation of beryllide samples is dependent on kinetics of growth BeO film. Indeed, the standard free energy of reaction Be + (1/2)O2 = BeO is strongly negative and corresponds to G = −993,695 J/mole O2 at 800 ◦ C [8]. From earlier studies of systems Ti–O2 [9] and V–O2 [10], it is known that the values of standard energies of formation of any titanium or vana-
P. Kurinskiy et al. / Fusion Engineering and Design 86 (2011) 2454–2457
dium oxide are higher than noted value of formation of BeO at 800 ◦ C. The formation of vanadium oxide V2 O5 can be explained by the presence of some vanadium-enriched regions on the surface of initial Be12 V sample, so that simultaneous oxidation of Be and V occurred. According to experimental results [11], the case of vanadium diffusion through BeO layer in V–BeO diffusion couple in the range between 800 and 1100 K is excluded, although the transport of Be through vanadium oxide film can be possible. Thus, BeO layer can also be formed on the surface of V2 O5 . From analysis of elemental distribution maps of Be and V and visual inspection of airannealed Be12 V specimen one can assume that only some regions contain V2 O5 . It is notable that BeO film has more homogeneous character of distribution compared to vanadium oxide. 4. Conclusions Comparative study of Be12 V and Be12 Ti specimens showed that both kinds of beryllides revealed similar brittle character of failure during constant-load compression tests at 600 and 800 ◦ C. Oxidation in air led to the growth of oxidized layers from 0.05 in initial state up to 0.3 m and from 0.03–0.04 to 0.7 m after annealing tests at 800 ◦ C for 1 h on the surfaces of Be12 Ti and Be12 V sam-
2457
ples, accordingly. In both cases, the formation of BeO film was detected by means of X-ray diffraction analysis. The formation of regions containing V2 O5 during the oxidation of Be12 V sample can be explained by non-homogeneous distribution of V in initial material. References [1] H. Yamada, Y. Nagao, H. Kawamura, M. Nakao, M. Uchida, H. Ito, Fusion Eng. Des. 69 (2003) 269. [2] T. Nishitani, H. Tanigawa, S. Jitsukawa, T. Nozawa, K. Hayashi, T. Yamanishi, et al., J. Nucl. Mater. 386–388 (2009) 405–410. [3] J. Reimann, L. Boccaccini, M. Enoeda, A.Y. Ying, Fusion Eng. Des. 61–62 (2002) 319–331. [4] G. Piazza, J. Reimann, G. Hofmann, S. Malang, A.A. Goraieb, H. Harsch, Fusion Eng. Des. 69 (2003) 227–231. [5] R.G. Macaulay-Newcombe, D.A. Thompson, J. Nucl. Mater. 212–215 (1994) 942–947. [6] E. Abramov, M.P. Riehm, D.A. Thompson, W.W. Smeltzer, J. Nucl. Mater. 175 (1990) 90–95. [7] R.A. Causey, J. Nucl. Mater. 300 (2002) 91–117. [8] G.E. Darwin, J.H. Buddery, Beryllium, Butterworth Scientific Publications, London, 1960, p. 76. [9] O. Kubaschewski, W.A. Dench, J. Inst. Met. 82 (1953) 87–91. [10] O. Kubaschewski, N.P. Allen, O. von Goldbeck, J. Electrochem. Soc. 98 (1951) 417. [11] R.A. Langley, J.M. Donhowe, J. Nucl. Mater. 63 (1976) 521–526.
Contents lists available at ScienceDirect
Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes
Comparative study of fusion relevant properties of Be12 V and Be12 Ti P. Kurinskiy a,∗ , V. Chakin a , A. Moeslang a , R. Rolli b , E. Alves c , L.C. Alves c , N. Franco c , Ch. Dorn d , A.A. Goraieb e a
Karlsruhe Institute of Technology, FZK, IMF I, P.O. Box 3640, 76021 Karlsruhe, Germany Karlsruhe Institute of Technology, FZK, IMF II, P.O. Box 3640, 76021 Karlsruhe, Germany Instituto Tecnologico e Nuclear, 2686-953 Sacavem, Portugal d Brush Wellman Inc., 14710 W. Portage River South Road, Elmore, OH 43416-9502, USA e GVT UG & Co. KG, In der Tasch 4a, 76227 Karlsruhe, Germany b c
a r t i c l e
i n f o
Article history: Available online 26 January 2011 Keywords: Titanium beryllide Vanadium beryllide Beryllium oxide Oxide surface layer
a b s t r a c t Very similar brittle behavior of failure of Be12 Ti and Be12 V cylindrical specimens has been observed after testing under constant loads at 600 and 800 ◦ C. Oxidation in air at 800 ◦ C of both types of beryllide samples was studied. The thickness of oxidized layers before and after annealing tests was evaluated by means of Ion Beam Analysis using Rutherford backscattering technique. X-ray diffraction analysis revealed the formation of beryllium oxide layer on the surface of Be12 Ti and Be12 V samples. Some quantity of vanadium oxide V2 O5 on the surface of airannealed vanadium beryllide sample related to a presence of vanadium-rich zones in initial material. © 2011 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Since titanium beryllide Be12 Ti and vanadium beryllide Be12 V are considered to be advanced materials for the use as neutron multipliers in the solid breeding blanket [1,2], the proper investigation of their mechanical properties and resistance to oxidation at elevated temperatures is needed. The materials of neutron multiplier are subjected to thermal stresses at temperatures of about 700–750 ◦ C during the operation of the breeding blanket in DEMO reactor and, therefore, the study of mechanical properties has been identified as one of the key issues for the blanket design [3,4]. Gas release characteristics of neutron multiplier are strongly influenced by the presence of oxide layer on the surface of beryllium-based materials. It is known that the diffusivity and solubility of hydrogen isotopes (e.g., tritium) is much smaller in BeO than in pure beryllium, so that, the thickness of the oxide film plays an important role in the ability of berylliumcontaining materials to accumulate and to release radiogenic gases [5–7].
2.1. Materials
∗ Corresponding author. Tel.: +49 7247 82 2908; fax: +49 7247 82 4567. E-mail addresses: [email protected], [email protected] (P. Kurinskiy). 0920-3796/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.fusengdes.2010.12.065
This work was performed using Be12 Ti and Be12 V intermetallic compounds delivered by Company Brush Wellman, Inc., USA. 2.2. Specimens and procedure of constant-load compression tests Cylindrical specimens having 3 mm diameter and 3.5 mm height were cut out of Be12 Ti and Be12 V bars using ultrasonic drilling device. Constant-load compression tests were performed in the closed glove-box system in Hot Cells (Fusion Materials Laboratory) at room temperature, 600 and 800 ◦ C. The test box was constantly purged with nitrogen in order to avoid the oxidation of specimens during the experiment. Constant load of 1000 N was applied uniaxially by means of ceramic plunger with the duration of 100 h for all tested specimens. One should note that this value of the compression force was maximal permissible in the glove-box. Due to a relatively high deviation of the displacement data of the plunger at elevated temperatures, the absolute deformation of cylindrical specimens was measured by extracting of the height values of samples after testing from the known initial height (3.5 mm). Having known diameter of the tested cylinders which is 3 mm and the compression load (1000 N), one can estimate the value of the compression stress in this experiment which is about 140 MPa.
P. Kurinskiy et al. / Fusion Engineering and Design 86 (2011) 2454–2457
Fig. 1. Be12 V specimen after compression testing at 800 ◦ C.
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Fig. 2. Be12 Ti cylindrical sample after loading at 800 ◦ C.
2.3. Investigation of oxidized layers The surface composition of Be12 Ti and Be12 V specimens was investigated at Institute of Nuclear Technologies (ITN) in Sacavem, Portugal. The thickness of the oxidized layers was evaluated on the beryllide specimens in as-received state and after annealing tests in a quartz tube in the electric resistance furnace 800 ◦ C for 1 h in the ambient atmosphere. The thickness of oxide layers on Be12 Ti and Be12 V specimens was investigated by means of Ion Beam Analysis using Rutherford Backscattering (RBS) technique. Particle-induced X-ray emission (PIXE) technique was used to analyze elemental distribution of alloying elements after annealing test in air. 1.6 MeV He+ and 2.0 MeV H+ focused microbeams (size 3 m × 4 m) were used during the surface study of beryllide specimens. 2.4. X-ray diffraction analysis
Fig. 3. RBS spectra of Be12 Ti specimen in as-received state.
Phase composition of as-received and annealed beryllide samples was measured by means of Bruker AXS D8 diffractometer in High Temperature Materials Laboratory, Ma3T, at ITN. 2 range from 10◦ to 90◦ with a step size of 0.02◦ and acquisition time of 1.5 s was used. 3. Results and discussion 3.1. Analysis of mechanical properties after compression tests No measurable deformation and visible cracks have been revealed after constant-load compression tests of both – Be12 Ti and Be12 V cylinders after loading at room temperature. Testing at 600 ◦ C showed that the specimens had some cracks which were parallel to the direction of the applied force and the values of absolute deformation for both beryllides were in the range of only few microns. Testing at 800 ◦ C showed the failure of Be12 Ti and Be12 V cylindrical samples: Be12 V specimen has been broken into some pieces apart (Fig. 1) and Be12 Ti has lost a big fragment (Fig. 2). Thus, both types of beryllides showed very similar brittle behavior of failure. 3.2. Evaluation of the surface of beryllide samples Evaluation of 1.6 MeV He+ RBS spectra obtained from the surface of as-received Be12 Ti (Fig. 3) and Be12 V (Fig. 4) specimens revealed that the oxidized surface layer was about 50 and 30–40 nm, accordingly. Some carbon contamination detected on the surface of Be12 Ti sample probably relates to a material handling.
Fig. 4. RBS spectra of initial Be12 V sample.
After annealing tests at 800 ◦ C for 1 h in air the surface of Be12 Ti sample changed to more tarnished colour and the surface of Be12 V specimen became two-coloured – the inclusions having metallic colour contrasted with a light-brown field. The results depicting the growth of the thickness of the oxidized layer on the surface of Be12 Ti and Be12 V after annealing at 800 ◦ C for 1 h in ambient atmosphere are shown in Fig. 5. The oxygen peak corresponding to Be12 V is broader than the same peak of Be12 Ti sample. Evaluation of RBS spectra of both beryllide specimens showed that Be12 V reacted with oxygen more intensively and the thick-
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P. Kurinskiy et al. / Fusion Engineering and Design 86 (2011) 2454–2457
Fig. 7. V and Be 530 m × 530 m).
elemental
distribution
maps
(scanned
surface
area
Fig. 5. RBS spectra of Be12 Ti and Be12 V samples annealed at 800 ◦ C in air.
Fig. 6. Ti and Be elemental distribution (scanned surface area 530 m × 530 m).
ness of oxidized layer is about 0.7 m. In the case of Be12 Ti sample, the oxygen-enriched layer was estimated to be around 0.3 m. The thickness of the oxidized layers on the surfaces of beryllide samples was evaluated by DAN32 software package. It is notable that the surface area of scanning with the size of approximately 0.2–0.3 mm2 was chosen during Ion Beam Analysis for all investigated specimens, so that different RBS spectra reflect only the average values of the thickness of oxidized layers. Character of distribution of alloying elements (Be, Ti and V) after annealing tests in air was investigated by means of PIXE and RBS. 2.0 MeV H+ beam focused down to a spot with size of 3 m × 4 m has been used during the scanning of the selected surface area (530 m × 530 m) of beryllide specimens. In the case of Be12 Ti specimen, homogeneous distribution of Be and Ti was observed indicating that Be- or Ti-depleted regions were absent on the surface (Fig. 6). V-depleted zones were observed after scanning of the surface of Be12 V sample. Contrasting regions which have the sizes up to hundreds of microns with different contents of V were detected (Fig. 7). Data obtained from the annealed Be12 V specimen showed that oxidized layer can have different stoichiometric contents depending on the surface region. 3.3. X-ray study of annealed beryllide specimens The results of X-ray diffraction analysis showed the presence of Be12 Ti and BeO on the surface of Be12 Ti air-annealed specimen (Fig. 8). High background in a low-angle 2 region could refer to a formation of amorphous layer or big amount of oxide particles with sizes of several nm which have certain influence on X-ray measurements. X-ray diffraction curve (Fig. 9) of Be12 V sample after annealing at 800 ◦ C in air depicts the evident presence of three phases – Be12 V,
Fig. 8. X-ray diffraction pattern of Be12 Ti specimen annealed at 800 ◦ C in air.
Fig. 9. X-ray diffraction pattern of Be12 V specimen after annealing test.
BeO and V2 O5. It is notable that the surface of Be12 V specimen seems to have fully crystalline state compared to Be12 Ti sample annealed at 800 ◦ C. Since the values of oxygen affinity for Be are higher than for Ti and V, the formation of BeO layer will be preferable from the point of view of thermodynamics in the case of oxidation of both kinds of beryllides – Be12 Ti and Be12 V. Beryllium reduces the oxides of titanium and vanadium during interaction with air at elevated temperatures and, thus, oxidation of beryllide samples is dependent on kinetics of growth BeO film. Indeed, the standard free energy of reaction Be + (1/2)O2 = BeO is strongly negative and corresponds to G = −993,695 J/mole O2 at 800 ◦ C [8]. From earlier studies of systems Ti–O2 [9] and V–O2 [10], it is known that the values of standard energies of formation of any titanium or vana-
P. Kurinskiy et al. / Fusion Engineering and Design 86 (2011) 2454–2457
dium oxide are higher than noted value of formation of BeO at 800 ◦ C. The formation of vanadium oxide V2 O5 can be explained by the presence of some vanadium-enriched regions on the surface of initial Be12 V sample, so that simultaneous oxidation of Be and V occurred. According to experimental results [11], the case of vanadium diffusion through BeO layer in V–BeO diffusion couple in the range between 800 and 1100 K is excluded, although the transport of Be through vanadium oxide film can be possible. Thus, BeO layer can also be formed on the surface of V2 O5 . From analysis of elemental distribution maps of Be and V and visual inspection of airannealed Be12 V specimen one can assume that only some regions contain V2 O5 . It is notable that BeO film has more homogeneous character of distribution compared to vanadium oxide. 4. Conclusions Comparative study of Be12 V and Be12 Ti specimens showed that both kinds of beryllides revealed similar brittle character of failure during constant-load compression tests at 600 and 800 ◦ C. Oxidation in air led to the growth of oxidized layers from 0.05 in initial state up to 0.3 m and from 0.03–0.04 to 0.7 m after annealing tests at 800 ◦ C for 1 h on the surfaces of Be12 Ti and Be12 V sam-
2457
ples, accordingly. In both cases, the formation of BeO film was detected by means of X-ray diffraction analysis. The formation of regions containing V2 O5 during the oxidation of Be12 V sample can be explained by non-homogeneous distribution of V in initial material. References [1] H. Yamada, Y. Nagao, H. Kawamura, M. Nakao, M. Uchida, H. Ito, Fusion Eng. Des. 69 (2003) 269. [2] T. Nishitani, H. Tanigawa, S. Jitsukawa, T. Nozawa, K. Hayashi, T. Yamanishi, et al., J. Nucl. Mater. 386–388 (2009) 405–410. [3] J. Reimann, L. Boccaccini, M. Enoeda, A.Y. Ying, Fusion Eng. Des. 61–62 (2002) 319–331. [4] G. Piazza, J. Reimann, G. Hofmann, S. Malang, A.A. Goraieb, H. Harsch, Fusion Eng. Des. 69 (2003) 227–231. [5] R.G. Macaulay-Newcombe, D.A. Thompson, J. Nucl. Mater. 212–215 (1994) 942–947. [6] E. Abramov, M.P. Riehm, D.A. Thompson, W.W. Smeltzer, J. Nucl. Mater. 175 (1990) 90–95. [7] R.A. Causey, J. Nucl. Mater. 300 (2002) 91–117. [8] G.E. Darwin, J.H. Buddery, Beryllium, Butterworth Scientific Publications, London, 1960, p. 76. [9] O. Kubaschewski, W.A. Dench, J. Inst. Met. 82 (1953) 87–91. [10] O. Kubaschewski, N.P. Allen, O. von Goldbeck, J. Electrochem. Soc. 98 (1951) 417. [11] R.A. Langley, J.M. Donhowe, J. Nucl. Mater. 63 (1976) 521–526.