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The structural properties and hydrogen permeation characteristics of ternary vanadium–iron–aluminum (V–Fe–Al) alloy were investigated. To achieve not only high hydrogen permeability but also strong resistance to hydrogen embrittlement, the alloy composition was modulated to show high hydrogen diffusivity but reduced hydrogen solubility. We demonstrated that matching the lattice constant to the value of pure V by co-alloying lattice-contracting and lattice-expanding elements was quite effective in maintaining high hydrogen diffusivity of pure V. [Copyright &y& Elsevier]

Abstract: We investigate the metal–hydrogen interaction in vanadium alloyed with X=Fe, Ni, Al, Ti, and Nb using first-principles calculations. The site energy of interstitial hydrogen depends on both the volume and the presence of a nearby alloying element; the two effects are analyzed separately. The effective volume of the alloying element follows the sequence Nb>Ti>Al>V>Ni>Fe, and a larger volume lowers the site energy on average. Locally, Al appears to be the strongest hydrogen repellent, and Ti exhibits the strongest affinity for hydrogen. The original tetrahedral coordination by the metal atoms is also affected and the effect is the most pronounced in Ni, where the hydrogen atom in the octahedral interstitial site is strongly stabilized. A 16-atom body centered cubic special quasi-random structure is utilized to obtain the statistical distribution of site energies in V12X4. The obtained site energies at 673K have the following sequence: Ti

Abstract: Thin sheets of V85Al10Co5 alloy were produced by a thermo-mechanical treatment consisting in successive hot rolling, cold rolling steps and annealing treatment at high temperature followed by either air cooling or water quenching. Though the values of hydrogen permeability measured for these sheets were significantly reduced as a consequence of the rolling process, the annealing treatment restored almost the hydrogen permeation properties to those of the alloy in the cast condition. EBSD analyses suggested that the post-annealing treatment performed at 1100 °C for 3 min after cold rolling induced a recrystallization of the grains resulting in a preferred orientation along the {002} planes. For the sample annealed and water quenched, the value of the hydrogen flux reached about 45 ml/cm2.min, which is more than twice the value of the flux obtained for thin foils of Pd alloys tested under identical conditions. [Copyright &y& Elsevier]

Abstract: CALPHAD type thermodynamic assessments for the V–M–H (M = Al, Co, Fe, Ni) hydrogen membrane systems have been carried out on the basis of a newly assessed Co–H binary description, a partly modified Fe–H description and existing thermodynamic descriptions for the other M–H (V–H, Al–H, Ni–H) and V–M (V–Al, V–Co, V–Fe, V–Ni) binary systems. A special attention was paid to estimate the thermodynamic descriptions for the non-existing bcc Al–H, Co–H and Ni–H alloys. Thermodynamic parameters for those binary alloys were estimated by using a theoretical approach (atomistic computation) and fitting limited amount of experimental data for the hydrogen solubility in V-rich bcc ternary alloys. The proposed thermodynamic descriptions predict phase equilibria, especially the effect of alloying elements on the hydrogen solubility in the V-rich bcc alloys, in good agreement with available experimental data. The present thermodynamic descriptions can be easily extended to higher order alloy systems and can provide useful information for alloy design of metallic hydrogen membranes with well-balanced hydrogen permeability and mechanical properties. [Copyright &y& Elsevier]

Abstract: The hydrogen permeation characteristics of alloy membranes based on Pd-coated V90Al10 alloy membrane have been investigated in the pressure range 1–3 atm under pure hydrogen and hydrogen–carbon dioxide gas mixture at 450 °C. Hydrogen permeation experiments have been confirmed that hydrogen flux was 21.1 ml/min/cm2 for a Pd-coated V90Al10 alloy membrane (thickness: 0.5 mm) using pure hydrogen as the feed gas. It has been found that Pd-coated V90Al10 alloy membranes exhibit good resistance to hydrogen embrittlement in pure hydrogen atmosphere. After different hydrogen permeation flux tests under different pressure condition in presence of hydrogen–carbon dioxide gas mixture, the characteristics of the Pd-coated V90Al10 alloy membranes were examined by ex-situ analysis techniques. The loss of cell performance observed in the presence of hydrogen–carbon dioxide gas mixture is mainly attributed to both physical and chemical degradations of membrane, which led to structural changes in the Pd-coated V90Al10 alloy membrane. [Copyright &y& Elsevier]

Abstract: V–Cr–Ti alloys are considered as one of the most promising candidate structural materials for fusion reactor. Hydrogen impurities originated from bombarding with reaction plasma as well as various nuclear transmutation reactions have a considerable influence on the performance and stability of V–Cr–Ti alloys. To understand the microscopic mechanism, we have simulated the behaviors of H atoms inside the pure vanadium solid as well as V-based alloys (V–4Cr–4Ti and V–5Cr–5Ti) using first-principles approach. The binding energies or absorption energies for H atom inside different interstitial sites were compared to determine the optimal trapping sites. Interaction between two interstitial H atoms was calculated and fit into a screened Coulomb potential. H atom prefers to diffuse along path between two nearest interstitial sites with low energy barriers of 0.20–0.34eV. [Copyright &y& Elsevier]

Abstract: W coating by vacuum plasma spray process and Cr coating by chromizing process were performed on fusion low activation materials, JLF-1 ferritic steel and NIFS-HEAT-2 vanadium alloy. The present study discusses feasibility of the coatings as anti-corrosion coating against fluoridation in Flibe for fusion low activation materials. Coatings were characterized by microstructural analysis and examination on chemical stability by corrosion tests. The corrosion tests were conducted with H2O–47% HF solution at RT and He–1% HF–0.06 H2O gas mixture at 823K to simulate fluoridation and oxidation in Flibe. The coatings presented suppression of fluoride formation compared with JLF-1 or NIFS-HEAT-2, however weight loss due to WF6 formation was induced, and much Cr2O3 was formed. [ABSTRACT FROM AUTHOR]

In current work, V-4Cr-4Ti and V-4Cr-4Ti-2Y alloys are prepared using mechanical alloying and spark plasma sintering. Sequential-beam irradiation of 30 keV H+ and 50 keV He+ ions, are carried out at 450 ℃ to the peak damage of 0.18 dpa. The influence of Y on the microstructure, mechanical properties, radiation induced defect and radiation-hardening are investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical test, and nano-indentation test. Two kinds of Y-rich particles precipitated in Y added alloy, one is Y 2 O 3 phase with a mean size of 60 nm, the other is YVO 4 with a diameter of ∼10 nm, but no carbide of Y is observed. The results show that Y can significantly improve plasticity of V base alloy, reduce the size and number density of radiation induced dislocation loops, limit radiation hardening. Two different fitting process with different initial values and boundary conditions are used to analysis radiation hardening, the fitting results indicate a slight softening of matrix near damage layer which named softened layer. This softened layer can affect nanoindentation test results especially for shallow irradiation. A plausible explanation for the formation of this softened layer could be the oxygen diffuses from unirradiated region to damage layer. [ABSTRACT FROM AUTHOR]

[Display omitted] • Micron-scale TiNi matrix with inside nano-scale VCr precipitates became amorphous while micron-scale VCr matrix including nano-scale TiNi precipitates exhibited a high structural stability in V 34 Ti 25 Cr 10 Ni 30 Pd 1 alloy after radiation. • The radiation tolerance of TiNi intermetallic compound in V 34 Ti 25 Cr 10 Ni 30 Pd 1 alloy was increased after nanocrystallization upon irradiation. • VCr solid solution phase exhibits a better radiation tolerance than TiNi intermetallic phase. Intermetallic compounds often have a low radiation tolerance due to the low recombination rate of radiation-induced defects. In the present work, we designed a novel multicomponent vanadium-based alloy (MVA), V 34 Ti 25 Cr 10 Ni 30 Pd 1 , containing a micron-scale TiNi matrix phase with VCr nanoprecipitates (NPs) and a micron-scale VCr matrix phase with TiNi NPs. The MVA was irradiated with 6 MeV Ti 3 + ions with a radiation dose of 5 × 10 15 i o n s / c m 2 at room temperature. Results indicated that the micron-scale intermetallic TiNi matrix along with VCr NPs inside both became amorphous, while the micron-scale VCr matrix including numerous intermetallic TiNi NPs both exhibited a high structural stability after ion irradiation. The intermetallic TiNi matrix becomes amorphous due to the accumulation of radiation-induced defects, and the intermetallic TiNi NPs in VCr matrix have a high stability of crystallographic structure due to high-density interfaces between NPs and matrix. These results indicate that the phase stability of TiNi intermetallic compound is increased after nanocrystallization. Besides, the discrepancy of two matrix phases including precipitates after ion irradiation, and the underlying mechanisms are discussed in detail in this work. This work gives a guidance for designing new vanadium alloys and intermetallic compounds with enhanced structural stability under ion irradiation. [ABSTRACT FROM AUTHOR]

Abstract: Development of ceramic coatings at inner wall of duct tubing is strongly required for self-cooled lithium/vanadium-alloy (Li/V-alloy) blanket concept to reduce magneto-hydrodynamics (MHD) pressure drop. In our previous study, erbium oxide (Er2O3) coatings fabricated by physical vapor deposition (PVD) method showed high electrical resistance and high compatibility with liquid lithium (Li). In situ formation of Er2O3 coatings was also explored to show oxygen in the V-alloy substrate and Er dissolved in Li could react to form thin Er2O3 layer at the interface. In this study, feasibility of self-healing of Er2O3 coating is explored by observing its in situ formation at cracks on the coatings fabricated by PVD method. V–4Cr–4Ti substrates were oxidized at 973K for 6h and annealed at 973K for 16h to introduce proper amount of oxygen into the substrates. The coatings deposited at room temperature (R.T.) were uniformly flat. On the contrary, the coatings deposited at 873K had peeled off at most areas. After introducing cracks on Er2O3 coatings by heating, the samples were exposed in liquid Li doped with Er at 873K for 100h and afterward at 973K for 100h to heal the cracks. At the large peeled-off areas, no in situ formation was observed, while the small cracks were healed. Peel-off of the coating indicates the intrusion of Li between the coating and the substrate. For improvement of self-healing of Er2O3 coatings, it is essential to progress in the adherence of them to the substrates and control the surface condition of the substrates. [Copyright &y& Elsevier]

Abstract: Using V–4Cr–4Ti as structural material in a V–Li blanket offers the blanket to operate at 350–750°C with high thermal efficiency. This paper investigates ways to strengthen V–4Cr–4Ti and the thermal stability of the strengthening. Results show that the alloy could be greatly strengthened in a proper ageing process, with insignificant loss of ductility or even higher static tensile fracture toughness. Cold rolling is found to be another approach for higher strength. Both strengthening are thermally stable at not more than 500°C. At higher temperature, the alloy in the sate of complete recrystallization shows better thermal stability than the alloy in solid solution state. For high performance of the V–Li blanket with good economic feature, the design of the blanket should consider to use V–4Cr–4Ti in various thermo-mechanical states in terms of the operation temperature. [Copyright &y& Elsevier]

Abstract: The in situ Er2O3 insulating coating is under development for the self-cooled Li/V-alloy type fusion blanket. In this study, the structural stability and self-healing capability of the coating are investigated. Since the cracking in the coating was not observed after exposure when Li was removed with a weak lotion (liquid NH3), the cracking observed in the previous studies is not a practical issue in a real blanket. The re-exposure of the coating in pure Li showed that the coating once formed in Li (Er) is thought to be stable in pure Li. Thus, coating has the possibility to be serviced in a Li environment without an Er supply. By prior exposure to Li (Er) at 873K, the exhaustion of the oxygen storage in V-alloy substrate during exposure at 973K could be delayed effectively. The self-healing capability of the coating was demonstrated by the examination with the re-exposing cracked coating in Li (Er). [Copyright &y& Elsevier]

Abstract: Mechanical alloying (MA) is a very effective means for microstructural control. However, MA inevitably accompanies contamination with impurities arising from milling vessels and balls. In this study effective usage of MA processed powders containing WC debris introduced from WC/Co vessels and balls is attempted to develop ultra-fine grained V–W–Y alloys with superior mechanical properties. V–8.4W–1.4Y and V–2.9W–1.6Y (mass%) alloys were fabricated by powder metallurgical methods utilizing MA, HIP and various thermo-mechanical treatments and then subjected to three-point bend impact and static tensile tests. It is shown that the post-HIP thermomechanical treatments lead to significant improvement in the ductility of the alloys: V–8.4W–1.4Y decarburized at 1573K possesses a grain size of approximately 400nm and exhibits full bend at 173K and tensile yield stress of 540MPa and uniform elongation of 13% at room temperature. Effects of WC debris on the mechanical properties and microstructures in the alloys are discussed. [Copyright &y& Elsevier]

Abstract: Many oxide and nitride coatings are under consideration worldwide for vanadium (V) structure to mitigate the magnetohydrodynamic (MHD) pumping power losses for the self-cooled lithium (Li) blanket system. To date, researchers have focused on the MHD resistance, compatibility, adherence, thermodynamic, and interface issues, paying little attention to the nuclear concerns. This assessment examines the nuclear-related issues for the leading coatings proposed for the self-healing approach in particular. Specifically, we assessed the impact of the coating additives to Li on the breeding potential of a typical Li/V system. An important outcome of this study has been to identify the coatings that compromise the breeding and rank the remaining candidates based on their nuclear behavior using the ARIES-RS operating conditions. It appears likely that the nuclear requirements will have an important impact on the choice of the coating material and on the maximum coating concentration in Li. Potential solutions that mitigate the effect of coatings and compensate for the breeding losses are discussed in the paper. However, these solutions introduce additional requirements and concerns that must be considered in future studies. [Copyright &y& Elsevier]

Abstract: Neutronics calculations were carried out to characterize self-cooled Li and Flibe blankets with vanadium alloy (V–4Cr–4Ti) structure, as advanced options for the Force Free Helical Reactor (FFHR-2). In the present paper, the parameter dependence of Tritium Breeding Ratio (TBR) and neutron shield performance was examined for a Li blanket (FFHR-LV) and a Flibe blanket (FFHR-FV). The TBR was independent from the Flibe composition between 30 and 45mol% of BeF2 in the case of the FFHR-FV. Due to the increase in the temperature range of the coolant Flibe as a result of the change of the structural materials from JLF-1 (low activation ferritic steel) to V–4Cr–4Ti, the fraction of BeF2 can be changed from 43 to 31mol% without changing the margin to coagulation of Flibe. The compositional change of Flibe resulted in a significant decrease in its viscosity. The decrease of TBR by the effects of MHD insulator coating with Er was negligibly small with the expected doping level of Er in the FFHR-LV. The increase in the B4C in the shielding material resulted in the decrease in the fast neutron flux at the superconducting magnet by 60–70% in both FFHR-LV and FFHR-FV. Optimum neutronics performance for the two blanket systems was derived by the calculation. [Copyright &y& Elsevier]

Abstract: The in situ Er2O3 insulating coating is under development for self-cooled Li/V-alloy type fusion blankets. A previous study showed formation and long-term stability of the coating by exposing V–4Cr–4Ti substrate to liquid Li doped with Er. In this study, the mechanisms for nucleation and growth of the coating are investigated. By oxidation and annealing, oxygen was charged into the substrate to form a Ti–O net phase as oxygen source to the coating. The surface layer formed on V–4Cr–4Ti consists of two sub-layers, an insulating Er2O3 coating and an intermediate layer of mixed ErN and Er–V–O. The measured growth rate shows logarithmic kinetics with high exponent (n ≈3 or 4) at 873 and 923K, suggesting that the rate of growth to Er2O3 coating should be very low. The growth was accelerated suddenly at 973K resulting in a low exponent (n ≈2) that almost obeys a parabolic law. A phenomenological model was proposed to describe the mechanism of coating, which showed the growth of the Er2O3 coating is controlled by the diffusion of oxygen and delivery of erbium to interface between V-alloys substrate and liquid Li. [Copyright &y& Elsevier]

Abstract: Helium was implanted into a V–4Ti alloy by using a 5keV helium ion beam with a flux of 1014 He/cm2 s, and then helium retention was analyzed by a technique of thermal desorption spectroscopy (TDS). The influence of heat treatment on helium trapping was studied by pre-annealing of the samples before ion irradiation. The annealing temperature was 973, 1223 and 1373K, respectively. Results indicated that pre-annealing treatments did not influence significantly the helium retention and release behavior in vanadium alloy on the present experimental conditions where the helium ion implantation fluence is in the region of 1017–1018 He/cm2, which shows a different tendency from the situation at a low fluence region (1013–1014 He/cm2). The reason could be due to different trap mechanisms of helium at different ion fluences. [Copyright &y& Elsevier]

Abstract: Helium irradiation experiments of V–4Cr–4Ti alloy with various surface treatments were conducted in an electron cyclotron resonance (ECR) ion irradiation apparatus. After helium ion irradiation at room temperature, the helium thermal desorption and retention properties were examined by thermal desorption spectroscopy (TDS). Ion energy of helium beam was 5keV. Three groups of desorption peaks appeared at around 500, 850 and 1200K in the TDS spectrum. After helium ion irradiation at ion fluence of 1×1021 He/m2, the retained helium desorbed mainly at around 1200K and all of the implanted helium atoms were retained. With increasing fluence up to 5×1021 He/m2, the amount of helium desorbed at 500K increased. For the polished samples with annealing at various temperatures, the desorption peak observed at around 500K shifted to higher temperature region. Smallest retained amount of helium was observed in the V-alloy with polishing followed by annealing at 1373K. [Copyright &y& Elsevier]

Abstract: Ferritic steel, vanadium alloy and SiC/SiC composite are candidate low activation materials for blanket components and first walls in fusion demonstration reactors. Several issues on these materials as the first wall have been investigated so far. Amount of deuterium retained in mechanically polished ferritic steel, F82H, after deuterium ion irradiation, was observed to be several times smaller than that of stainless steel, 316L SS. Physical sputtering yield of the ferritic steel due to deuterium ion was comparable to that of 316L SS. These results suggest that the property of the ferritic steel as the first wall material is superior to that of 316L SS, with respect to fuel hydrogen retention and in-vessel tritium inventory. Since first walls of blanket modules are exposed to both fuel hydrogen and helium, the helium is also trapped in the walls. Helium retention of V–4Cr–4Ti was investigated using helium ion irradiation apparatus. The amount of helium retained was comparable to those of other plasma facing materials. One of the major concerns in use of SiC/SiC composite for blanket is permeation of helium gas coolant into fusion plasma. Helium gas permeability of the SiC/SiC composite after heat cycles was measured using a vacuum device consisting two chambers. The increase in the permeability was not observed when the heating rate was suitably adjusted. Therefore, the blanket module may be made using only SiC/SiC composite if a vacuum pumping for the inside of blanket module is attached. [Copyright &y& Elsevier]

Abstract: MHD pressure drop in flowing liquid metal for a tokamak with high magnetic fields is a key concern regarding the development of lithium self-cooled test module for ITER and lithium breeding blanket for DEMO-type projects. MHD losses on liquid metal pumping can be most efficiently reduced by applying of an electrically insulating coating to the inner surface of the channels. The developed method to evaluate the electrically insulating properties of a coating placed on the internal surface of a vanadium test channel is based on the pressure drop measurement in a liquid lithium forced circulation system with the test section in magnetic field. The tests were conducted on channels of V–4Ti–4Cr alloy with and without on insulating coating based on the aluminum nitride technique (AlN) . The dimensions of the test section were 6mm×20mm×320mm. The tests involved lithium flow velocities up to 3m/s, temperatures up to 400°C and a uniform transverse magnetic field up to 1.6T. The measured hydraulic resistances have shown five times reduction for the coated wall channel in comparison with the conducting wall channel. [Copyright &y& Elsevier]

Abstract: An electrically insulating coating is under development to mitigate magneto-hydrodynamic (MHD) pressure drop in self-cooled Li/V-alloy blanket. A previous study showed the feasibility of in situ formation of an Er2O3 coating by exposing V–4Cr–4Ti to liquid Li doped with Er at high temperature. In this paper, the characteristics and the long-term stability of such a coating were investigated. A V–4Cr–4Ti substrate was oxidized in flowing Ar at 973K, annealed in vacuum at 973K and finally exposed to liquid Li doped with Er from 773 to 973K. The oxygen charged and homogenized at the surface of the substrate that acted as a source for coating formation. The surface layer formed on V–4Cr–4Ti consists of double sub-layers, namely an insulating coating of Er2O3 and an intermediate layer of mixed ErN and V-compounds. The Er2O3 coating was found stable up to 750h of exposure time in liquid Li at 873K with its saturated thickness of ∼0.1μm. The coating was stable up to 300h at 973K with its thickness increased to ∼1.2μm. Cracks were observed in coatings formed at 923 and 973K. The mechanism of cracking is under investigation. [Copyright &y& Elsevier]

Helium irradiation experiments of V–4Ti alloy were conducted in an ECR ion irradiation apparatus by using helium ions with energy of 5keV. The ion fluence was in the range from 1×1017He/cm2 to 8×1017He/cm2. After the helium ion irradiation, the helium retention was examined by using a technique of thermal desorption spectroscopy (TDS). After the irradiation, the blisters with a size of about 0.1μm were observed at the surface, and the blister density increased with the ion fluence. Two desorption peaks were observed at approximately 500 and 1200K in the thermal desorption spectrum. When the ion fluence was low, the retained helium desorbed mainly at the higher temperature regime. As increase of the ion fluence, the desorption at the lower temperature peak increased and the retained amount of helium saturated. The saturated amount was approximately 2.5×1017He/cm2. This value was comparable with those of the other plasma facing materials such as graphite. [Copyright &y& Elsevier]

In this Letter we report on the electrical resistivity and magneto-resistivity of disordered V80Al20-xFex alloys in the temperature range 1.5⩽T⩽300 K and analyze them in the light of weak localization and electron–electron interaction. The low temperature zero field resistivity obeys a T1/2 law, which is explained by electron–electron interaction. The low field magneto-resistivity is described by weak localization theory under strong spin–orbit interaction. The electron–phonon scattering rate obeys a quadratic temperature dependence. This observation is interpreted by the existing theories of electron–phonon interaction. [Copyright &y& Elsevier]

Corrosion behaviour of Aluminum nitride (AlN) as a candidate material for insulating coating for V/Li blanket was investigated by corrosion experiments in liquid lithium (Li) up to 1073 K for 1000 h. High purity AlN samples decreased their weights after the sintering test in Li in contact with vanadium alloy over 973 K, while those in Li not in contact with the vanadium alloy survived up to 1073 K. Nitrogen dissolution from AlN into the liquid Li and absorption of dissolved nitrogen by vanadium alloy are considered to be a corrosion mechanism. Small decreases of electrical resistance were observed after the sintering tests over 873 K because of the conductive corrosion layer on the surface caused by the nitrogen dissolution. In the cases of low purity AlN samples sintered over 973 K, large weight decreases were explained by fragile grain boundary caused by oxygen dissolution. The oxygen dissolution may also results in the resistivity decrease even at 723 K. Therefore, decrease of oxygen impurity in AlN and addition of nitrogen in liquid Li are considered to give a possible solution to the Li/AlN corrosion problem in the Li/AlN/V alloy blanket system. [Copyright &y& Elsevier]

This paper reports the improvements achieved in the tribological performance of V 5 at% Ti vanadium-based alloy ion implanted with nitrogen at low energy. Nitrogen ion implantation was carried out at 400°C with a current density of 1 mA/cm2 and an accelerating voltage of 1.2 kV. Nanoindentation tests showed hardness increases by a factor close to 3. Ball-on-disk tests showed a decrease in friction coefficient. The thickness of the active implanted layer estimated from the nanoindentation tests is close to 500 nm. A clear correlation between the improvement in the tribological properties: hardness, friction and wear and the implanted layer has been observed. [Copyright &y& Elsevier]

Microstructure and irradiation hardening of V-4Cr-4Ti alloys with different yttrium (Y) contents were studied by self-ion irradiation at 550 °C via TEM and nano-indentation test technology. The peak damage of the V-4Cr-4Ti-xY alloy (x = 0, 0.1, 0.5, and 1, wt.%) irradiated by 2.5 MeV self-ion (V2+) is 8 dpa. Dense dislocation loops were observed in all vanadium alloy samples after irradiation. With the increase of Y content, both average size and number density of dislocation loops using g = <110> near the pole [001] decreased, while the irradiation hardness increment first decreased and then increased. In order to better reduce the irradiation hardening, it is considered that the addition of 0.1 wt.% Y in V-4Cr-4Ti alloy is reasonable. [ABSTRACT FROM AUTHOR]

Abstract: In this letter, our aim is to explore the properties of a new class of high-performance membranes for hydrogen separation applications prepared from boron-doped vanadium–aluminum alloys. In particular, we present the first hydrogen permeation characteristics of Pd-coated V99.8−xAlxB0.2 (x=0, 10) alloy membranes. Membranes have been investigated in the pressure range 1.5–3.0bar under pure hydrogen and hydrogen–carbon dioxide gas mixture at 400°C. Hydrogen flux is found on the order of 48mL/min/cm2 for a Pd-coated V99.8B0.2 alloy membrane (thickness: 0.5mm) using pure hydrogen as the feed gas. [Copyright &y& Elsevier]

Dissimilar-metals bonding between V–4Cr–4Ti and Hastelloy X alloy was investigated by explosive welding, which is essential to connect coolant pipes of Flibe blanket and external components such as tritium extractor and heat exchanger in fusion reactor. The nano-indentation hardness and corresponding microstructure at the interface are evaluated. After the explosive welding, a characterization of the typical wavy interface indicates good weldability. Discontinuous vortex regions appear at the interface and reveal obvious hardening up to 806 HV. Microstructural analysis indicates that the interlayer consists of Ni 37.1 V 21 Cr 20.5 Fe 15.4 Mo 4.4 Ti 1.0 Co 0.6 with a fcc lattice structure and a high density of dislocations, and no intermetallic forms. Based on the compositions, the formation of solid solution was predicted by the entropy and enthalpy of the multi-component alloy system, despite the phase diagrams of binary alloys of the constituent elements indicating the formation of intermetallics. Study of hardening mechanism at the interlayer indicates that obvious hardening is mainly attributed to solid-solution hardening and dislocation hardening. [ABSTRACT FROM AUTHOR]