Hydrogen Permeation Properties of Nb-Based Two-Phase Compounds

2007 ◽  
Vol 561-565 ◽  
pp. 467-470
Author(s):  
Yuji Yamaguchi ◽  
Kyosuke Kishida ◽  
Katsushi Tanaka ◽  
Haruyuki Inui ◽  
Sho Tokui ◽  
...  
Keyword(s):  
Hydrogen Embrittlement ◽  
Hydrogen Permeation ◽  
Membrane Surface ◽  
Hydrogen Permeability ◽  
Eutectic Structure ◽  
Growth Direction ◽  
Directionally Solidified ◽  
Two Phase ◽  
Cast Sample ◽  
Lamellar Type

Nb-NiTi and Nb-CoTi eutectic alloys were directionally solidified in an optical floating zone furnace. Rod-type eutectic structures with Nb rods aligned parallel to the growth direction are obtained for Nb-41Ni-40Ti grown at relatively slow growth rates below 1.0mm/h, while lamellar-type eutectic structures are obtained for Nb-35Co-34Ti grown at the same condition. The hydrogen permeability for the Nb-41Ni-40Ti DS alloy with Nb rods perpendicular to the membrane surface is 2.60×10-8mol H2 m-1 Pa-1/2 at 673K, which is about 2.5 times higher than that of as-cast sample. No hydrogen embrittlement is observed between 573 and 673K, indicating that the Nb-NiTi rod-type eutectic structure effectively suppresses the hydrogen embrittlement of Nb during hydrogen permeation.

Microstructures and Hydrogen Permeability of Nb-NiTi Eutectic Alloys Prepared by Directional Solidification

2006 ◽  
Vol 980 ◽  
Author(s):  
Yuji Yamaguchi ◽  
Kyosuke Kishida ◽  
Sho Tokui ◽  
Kazuhiro Ishikawa ◽  
Katsushi Tanaka ◽  
...  
Keyword(s):  
Hydrogen Embrittlement ◽  
Alloy Composition ◽  
Slow Growth ◽  
Hydrogen Permeability ◽  
Eutectic Structure ◽  
Eutectic Alloys ◽  
Directionally Solidified ◽  
Direction Parallel ◽  
Columnar Grains ◽  
Niti Matrix

AbstractThe Nb-NiTi eutectic alloys were directionally solidified (DS) in an optical floating zone furnace. Columnar grains of eutectic structures containing rod-shaped Nb in the NiTi matrix is observed in the DS ingots irrespective of the alloy composition. Well-aligned rod-type eutectic microstructures can be obtained for samples with a composition of Nb-41Ni-40Ti grown at relatively slow growth rates below 2.5mm/h. The hydrogen permeability along the direction parallel to the Nb rods of Nb-41Ni-40Ti DS alloy grown at 1mm/h is 2.60×10-8mol H2 m-1 Pa-1/2 at 673K, which is over 20 times higher than that measured perpendicular to the Nb-rod direction. No hydrogen embrittlement is observed between 573 and 673K indicating that the eutectic structure itself is favorable in suppressing the hydrogen embrittlement of Nb.

Growth and scintillation properties of LiBr/CeBr3 eutectic scintillator for neutron detection

2021 ◽  
Author(s):  
Ryuga Yajima ◽  
Kei Kamada ◽  
Yui Takizawa ◽  
Masao Yoshino ◽  
Kyoung Jin Kim ◽  
...  
Keyword(s):  
Thermal Neutron ◽  
Gamma Ray ◽  
Neutron Detection ◽  
Eutectic Structure ◽  
Growth Direction ◽  
Emission Peak ◽  
Molar Ratio ◽  
X Ray ◽  
Vertical Bridgman ◽  
Lamellar Type

Abstract The 6LiBr/CeBr3 eutectic scintillator for thermal neutron detection has been developed due to achieving high 6Li concentration. The eutectics were grown by vertical Bridgman method. Molar ratio of 6Li in 6LiBr/CeBr3 eutectic is 35 %, which is higher than that of commercial neutron scintillators such Ce:LiCaAlF6 and Ce:Cs2LiYCl6. The grown eutectic had lamellar-type eutectic structure extending along the growth direction and optical transparency. The grown eutectics showed an emission peak at 360 and 380 nm ascribed to Ce3+ 4f-5d transition from CeBr3 scintillation phase. The measurements of scintillation performance of the 6LiBr/CeBr3 were performed using x-ray, gamma-ray and neutron irradiation to evaluate its potential as a neutron scintillator.

Submicron Conductor Array Fabricated from a Recrystallized Eutectic Thin Film

1982 ◽  
Vol 13 ◽  
Author(s):  
H. E. Cline
Keyword(s):  
Thin Film ◽  
Eutectic Alloy ◽  
Solidification Rate ◽  
Eutectic Structure ◽  
Alloy Thin Film ◽  
Directionally Solidified ◽  
Two Phase ◽  
Glass Substrates ◽  
Solid Liquid Interface ◽  
Solid Liquid

ABSTRACTA submicron conductor array was fabricated without using lithography by selectively etching a recrystallized A1-A12Cu eutectic alloy thin film. The 2 micron thick eutectic films were deposited on glass substrates and directionally solidified with both a quartz-iodine lamp and a scanning laser at rates between .0016 and .14 cm/sec. The resulting structure consisted of alternate parallel stripes of the two eutectic phases with a spacing between .5 and 4 microns that was controlled by the solidification rate. An array of submicron Al- rich conductors was fabricated by selectively etching away the Al2 Cu phase. At solidification rates greater than .004 cm/sec using the lamp heater the solid-liquid interface became non-planar while with the laser the structure was well alligned at the highest rates used, .14 cm/sec. At the maximum theoretical solidification rate that produces a two phase aligned eutectic structure the width of the Al wires would be 100A.

Microstructures and Mechanical Properties of MoSi2 / Mo5Si3 / Mo5Si3C Ternary Eutectic Composite

2015 ◽  
Vol 1760 ◽  
Author(s):  
Hirotaka Matsunoshita ◽  
Kosuke Fujiwara ◽  
Yuta Sasai ◽  
Yuichiro Kondo ◽  
Kyosuke Kishida ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Ternary Eutectic ◽  
Growth Direction ◽  
Compression Tests ◽  
Eutectic Composite ◽  
Directionally Solidified ◽  
Microstructures And Mechanical Properties ◽  
Image Position ◽  
Lamellar Type ◽  
Crystalline Matrix

ABSTRACTMicrostructures and mechanical properties of directionally solidified (DS) MoSi2 / Mo5Si3 / Mo5Si3C ternary eutectic composites were investigated. Ternary eutectic microstructure of a script-lamellar type that is characterized by rod-shaped Mo5Si3 and Mo5Si3C phases extending along the growth direction in the MoSi2 single crystalline matrix was developed simply by directional solidification at a growth rate of 10 mm/h. Compression tests along $[{\rm{1}}\mathop 1\limits^- 0]_{MoSi_2 }$ nearly parallel to the growth direction revealed that the DS ternary eutectic composites were plastically deformed above 1000 °C. Yield stresses of the DS ternary eutectic composites were much higher than those of binary composites mainly because of a smaller average thickness of MoSi2 matrix.

scholarly journals A Review for Consistent Analysis of Hydrogen Permeability through Dense Metallic Membranes

Membranes ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 120
Author(s):  
Asuka Suzuki ◽  
Hiroshi Yukawa
Keyword(s):  
Diffusion Coefficient ◽  
Hydrogen Embrittlement ◽  
Alloy Composition ◽  
Hydrogen Permeation ◽  
Hydrogen Permeability ◽  
Anomalous Temperature Dependence ◽  
Anomalous Temperature ◽  
High Hydrogen ◽  
Hydrogen Flux ◽  
Solubility Constant

The hydrogen permeation coefficient (ϕ) is generally used as a measure to show hydrogen permeation ability through dense metallic membranes, which is the product of the Fick’s diffusion coefficient (D) and the Sieverts’ solubility constant (K). However, the hydrogen permeability of metal membranes cannot be analyzed consistently with this conventional description. In this paper, various methods for consistent analysis of hydrogen permeability are reviewed. The derivations of the descriptions are explained in detail and four applications of the consistent descriptions of hydrogen permeability are introduced: (1) prediction of hydrogen flux under given conditions, (2) comparability of hydrogen permeability, (3) understanding of the anomalous temperature dependence of hydrogen permeability of Pd-Ag alloy membrane, and (4) design of alloy composition of non-Pd-based alloy membranes to satisfy both high hydrogen permeability together with strong resistance to hydrogen embrittlement.

Microstructures and Mechanical Properties of in-situ V-V3B2 Composites

2006 ◽  
Vol 980 ◽  
Author(s):  
Sujing Xie ◽  
Easo P. George
Keyword(s):  
Tensile Tests ◽  
Eutectic Structure ◽  
Growth Direction ◽  
Solid Solution Alloy ◽  
Directionally Solidified ◽  
Arc Melting ◽  
Composite Microstructure ◽  
Two Phases ◽  
Microstructural Examination

AbstractA series of binary V-B alloys, with compositions spanning the eutectic, were produced by arc melting and drop casting. Microstructural examination revealed that the fully eutectic structure occurs at V-11B rather than V-15B as reported in the V-B phase diagram (all compositions in at.%). The V-11B eutectic was directionally solidified in an optical floating zone furnace, resulting in a composite microstructure consisting of a V matrix and flake or trigonal shaped V3B2 phase. The boride flake spacing (ë) decreases with increasing growth rate (R), following the relation ë2.56R=C, where C is a constant. TEM observations showed that the orientation relationship between the V and V3B2 phases is given by: [001]V // [001]V3B2 and (100)V // (100)V3B2. The growth direction and the V/V3B2 interface are parallel to the [001] direction and (100) planes in the two phases, respectively. Tensile tests were used to investigate the temperature dependence of the strength and ductility of the composite. At temperatures to 600°C, the yield strength of the eutectic is about 140 MPa higher than that of a commonly used vanadium solid-solution alloy, V-4Cr-4Ti. Surprisingly, the eutectic shows 5% tensile ductility at room temperature which increases to 10% as the test temperature is raised to 800°C.

Effects of Initial Nucleation Condition at the Start Block on the Grain Size and Growth Direction in Directionally Solidified CM247LC Superalloy

2011 ◽  
Vol 49 (01) ◽  
pp. 58-63
Author(s):  
Hye-Young Yoon ◽  
Je-Hyun Lee ◽  
Hyeong-Min Jung ◽  
Seong-Moon Seo ◽  
Chang-Young Jo ◽  
...  
Keyword(s):  
Grain Size ◽  
Growth Direction ◽  
Directionally Solidified ◽  
Initial Nucleation

scholarly journals Correlation between Microstructure and Hydrogen Degradation of 690 MPa Grade Marine Engineering Steel

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 851
Author(s):  
Heng Ma ◽  
Huiyun Tian ◽  
Juncheng Xin ◽  
Zhongyu Cui
Keyword(s):  
Crack Propagation ◽  
Base Metal ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Steel Substrate ◽  
Phase Interface ◽  
Grain Structure ◽  
Hydrogen Degradation ◽  
Two Phase ◽  
Annealed Steel

Electrochemical H charging, hydrogen permeation, and hydrogen-induced cracking (HIC) behavior of 690 MPa grade steel substrate and different heat-treatment states (annealed, quenched, normalized, tempered) are investigated by cyclic voltammetry (CV), hydrogen permeation, electrochemical H charging, and slow strain rate tensile test (SSRT). The results show that hydrogen diffuses through the steel with the highest rate in base metal and the lowest rate in annealed steel. The hydrogen-induced cracks in base metal show obvious step shape with tiny cracks near the main crack. The cracks of annealed steel are mainly distributed along pearlite. The crack propagation of quenched steel is mainly transgranular, while the hydrogen-induced crack propagation of tempered steel is along the prior austenite grain boundary. HIC sensitivity of base metal is the lowest due to its fine homogeneous grain structure, small hydrogen diffusion coefficient, and small hydrogen diffusion rate. There are many hydrogen traps in annealed steel, such as the two-phase interface which provides accommodation sites for H atoms and increases the HIC susceptibility.

scholarly journals Hydrogenation Property and Eutectic Structure of a Mg-Mg2Ni Two-Phase Alloy

2005 ◽  
Vol 69 (9) ◽  
pp. 810-814 ◽  
Author(s):  
Kosei Kominato ◽  
Hirofumi Homma ◽  
Hideyuki Saitoh
Keyword(s):  
Eutectic Structure ◽  
Two Phase

Comparison of four types of membrane bioreactor systems in terms of shear stress over the membrane surface using computational fluid dynamics

2013 ◽  
Vol 68 (12) ◽  
pp. 2534-2544 ◽  
Author(s):  
N. Ratkovich ◽  
T. R. Bentzen
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Membrane Fouling ◽  
Two Phase Flow ◽  
Membrane Surface ◽  
Cross Flow ◽  
Membrane Bioreactors ◽  
Phase Flow ◽  
Two Phase ◽  
Computational Fluid Dynamics Cfd

Membrane bioreactors (MBRs) have been used successfully in biological wastewater treatment to solve the perennial problem of effective solids–liquid separation. A common problem with MBR systems is clogging of the modules and fouling of the membrane, resulting in frequent cleaning and replacement, which makes the system less appealing for full-scale applications. It has been widely demonstrated that the filtration performances in MBRs can be greatly improved with a two-phase flow (sludge–air) or higher liquid cross-flow velocities. However, the optimization process of these systems is complex and requires knowledge of the membrane fouling, hydrodynamics and biokinetics. Modern tools such as computational fluid dynamics (CFD) can be used to diagnose and understand the two-phase flow in an MBR. Four cases of different MBR configurations are presented in this work, using CFD as a tool to develop and optimize these systems.

Sign in / Sign up

Export Citation Format

Share Document