Anisotropic Microstructure and Hydrogen Permeability of Nb-Ti-Ni Duplex Phase Alloy Prepared by Hot Forging-Rolling Technique

2006 ◽  
Vol 980 ◽  
Author(s):  
Sho Tokui ◽  
Kazuhiro Ishikawa ◽  
Kiyoshi Aoki
Keyword(s):  
Solid Solution ◽  
Hydrogen Embrittlement ◽  
Hydrogen Permeability ◽  
Rolling Direction ◽  
Hot Forging ◽  
The Other ◽  
Rolling Reduction ◽  
Eutectic Microstructure ◽  
Ni Alloys ◽  
Other Hand

AbstractIt has been demonstrated that the as-cast Nb40Ti30Ni30 duplex phase alloy, which consists of the primary (Nb, Ti) solid solution and the fine lamellar type eutectic {TiNi+(Nb, Ti)} phase, shows higher hydrogen permeability ¶ than that of pure Pd without the hydrogen embrittlement at 673K. In this alloy, the eutectic phase contributes to the suppression of the hydrogen embrittlement, while the primary one does mainly to the hydrogen permeation. It is important to note that even if the eutectic microstructure disappears and is replaced by the small spherical (Nb, Ti) phase embedded in the TiNi matrix by rolling and subsequent annealing, its high hydrogen permeability and large resistance to the hydrogen embrittlement are sustained. Furthermore, the present authors have observed that the primary (Nb, Ti) phase is largely elongated along the rolling direction. Consequently, it is expected that rolled and annealed Nb-Ti-Ni alloys show the large anisotropy of the microstructure and the hydrogen permeability. In the present work, the microstructure and hydrogen permeability ¶nof the Nb40Ti30Ni30 alloy after rolling and annealing treatments are examined in order to develop highly hydrogen permeable alloys utilizing the anisotropic microstructure.The primary (Nb, Ti) phase and the very fine eutectic {TiNi+(Nb, Ti)} phase are observed in the as-cast Nb40Ti30Ni30 alloy by scanning electron microscopy (SEM). The X-ray diffractometry (XRD) indicates that this alloy consists of the B2-TiNi intermetallic compounds and the bcc- (Nb, Ti) solid solution. The primary (Nb, Ti) phase is largely elongated along the rolling direction by forging and subsequent rolling at 1173 K. On the other hand, the eutectic microstructure becomes unclear with increasing the rolling reduction. The composite alloys in which the (Nb, Ti) phase is elongated along to the rolling direction are obtained by 69 % rolling reduction. ¶n of this sample is four times higher than that of as-cast one. On the other hand, ¶ for the sample vertical to the rolling direction is reduced to about one third of that of as-cast one. Thus, the hydrogen permeability of the Nb40Ti30Ni30 alloy varies about ten times or more depending on the direction of the primary¡]Nb, Ti¡^ phase. We conclude that it is possible to produce highly hydrogen permeable Nb-Ti-Ni alloys using the anisotropy of the microstructure prepared by hot forging and rolling.

Microstructure and Hydrogen Permeability of Duplex Phase M-ZrNi (M=V, Nb, Ta) Alloys

2006 ◽  
Vol 980 ◽  
Author(s):  
Kazuhiro Ishikawa ◽  
Naoshi Kasagami ◽  
Tomoyuki Takano ◽  
Kiyoshi Aoki
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
High Performance ◽  
Gas Flow ◽  
Hydrogen Permeation ◽  
Hydrogen Permeability ◽  
The Other ◽  
Cast State ◽  
X Ray ◽  
Scanning Electron

AbstractIn order to develop non-Pd based high performance hydrogen permeation alloys, microstructure, crystal structure and hydrogen permeability of duplex phase M-ZrNi (M=V and Ta) alloys were investigated using a scanning electron microscope, an X-ray diffractometer and a gas flow meter. These results were compared with those of Nb-ZrNi ones which have been previously published. The hydrogen permeation was impossible in the V-ZrNi alloys, because they were brittle in the as-cast state. On the other hand, duplex phase alloys consisting of the bcc-(Ta, Zr) solid solution and the orthorhombic ZrNi (Cmcm) intermetallic compound were formed and hydrogen permeable in the Ta-ZrNi system. The Ta40Zr30Ni30 alloy shows the highest value of hydrogen permeability of 4.1×10-8 [molH2m-1s-1Pa-0.5] at 673 K, which is three times higher than that of pure Pd.

scholarly journals Microstructure Evolution and Mechanical Stability of Supersaturated Solid Solution Co-Rich Nanocrystalline Co-Cu Produced by Pulsed Electrodeposition

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2616 ◽  
Author(s):  
Killang Pratama ◽  
Jenifer Barrirero ◽  
Frank Mücklich ◽  
Christian Motz
Keyword(s):  
Solid Solution ◽  
Supersaturated Solid Solution ◽  
The Other ◽  
Bending Test ◽  
High Yield ◽  
Grain Coarsening ◽  
Bending Tests ◽  
Annealing Temperatures ◽  
Other Hand ◽  
Pulsed Electrodeposition

Thick films of supersaturated solid solution nanocrystalline Co-Cu (28 at.% Cu) were synthesized through the pulsed electrodeposition technique. Microstructural changes of nanocrystalline Co-Cu were intensively studied at various annealing temperatures. Annealing at 300 °C results in a spinodal decomposition within the individual grains, with no grain coarsening. On the other hand, distinct phase separation of Co-Cu is detected at annealing temperatures beyond 400 °C. Static micro-bending tests show that the nanocrystalline Co-Cu alloy exhibits a very high yield strength and ductile behavior, with no crack formation. Static micro-bending tests also reported that a large plastic deformation is observed, but no microstructure change is detected. On the other hand, observation on the fatigue resistance of nanocrystalline Co-Cu shows that grain coarsening is observed after conducting the cyclic micro-bending test.

Microstructural Control by a Rolling-Annealing Technique and Hydrogen Permeability in the Nb-Ti-Ni alloys

2005 ◽  
Vol 885 ◽  
Author(s):  
Sho Tokui ◽  
Kazuhiro Ishikawa ◽  
Kiyoshi Aoki
Keyword(s):  
Heat Treatment ◽  
Cold Rolling ◽  
Gas Flow ◽  
Hydrogen Permeability ◽  
Rolling Reduction ◽  
Solid Solution Alloy ◽  
X Ray ◽  
Ni Alloys ◽  
Cold Rolling Reduction ◽  
Ni Alloy

ABSTRACTCold rolling reduction, microstructural changes induced by cold rolling and subsequent heat treatment, hydrogen permeability (Φ) of Nb-Ti-Ni duplex phase alloys have been investigated using a rolling machine, a scanning electron microscope (SEM), an X-ray diffractometer (XRD) and a gas flow technique. The Nb-Ti-Ni alloys on the line connecting the TiNi compound and the Nb90Ti10 solid solution alloy show higher rolling reduction of 70 % or more at room temperature. The value of Φ for the Nb40Ti30Ni30 alloy, which is higher than that of pure Pd at 673K, decreases with increasing rolling reduction and attains to one third of that of the original one by the 50 % rolling reduction. The eutectic microstructure consisting of {TiNi+(Nb, Ti)} phases disappears and is replaced by the (Nb, Ti) phase embedded in the TiNi matrix by heat treatment 1073 K or more and for 605ks in a vacuum. However, its Φ value remains as it was by annealing at 1273 K or less, while it increases with increasing annealing periods at 1373 K or more and recovers to the original value after annealing for 605ks. These experimental results indicate that rolling and annealing techniques are the useful method for the preparation of a hydrogen permeable Nb-Ti-Ni alloy membrane.

ANALYSIS ON THE MICROSTRUCTURE OF THE AS-CAST AND EXTRUDED Mg-(6-10)Li-3Al-Ce-Ca ALLOYS

2009 ◽  
Vol 23 (06n07) ◽  
pp. 920-926 ◽  
Author(s):  
LIREN CHENG ◽  
ZHANYI CAO ◽  
RUIZHI WU ◽  
MILIN ZHANG
Keyword(s):  
Solid Solution ◽  
Microstructural Characterization ◽  
Eutectic Structure ◽  
The Other ◽  
Β Phase ◽  
Other Hand ◽  
Long Rod

Microstructural characterization of as-cast and extruded experimental alloys as (A) Mg -6.86 Li -3.02 Al -1.12 Ce -0.7 Ca (B) Mg -8.15 Li -3.07 Al -1.12 Ce -0.72 Ca (C) Mg -10.54 Li -3.54 Al -1.23 Ce -0.94 Ca are researched in this paper. The results show that the as-cast specimens of (A) and (B) are composed of α ( Mg ) phase, β ( Li ) phase, rod-like and bulk Al 2 Ce compound. On the other hand, β phase ( Li ), bulk and rod-like Al 2 Ce compound, Al2 Ca compound at boundaries are observed in the as-cast (C) alloy. The addition of Ce and Ca also shows in the microstructure the presence of Al - Ce - Ca phase, a solid solution of Ca in Al 2 Ce compound. In the extruding alloys, the microstructure is refined and the β phase has the effect of coordination during deformation. The long rod-like and the bulk compounds become short rods and fine clumps distributing evenly in the extruding direction after extruding process. The microstructure of extruded Mg -10.54 Li -3.54 Al -1.23 Ce -0.94 Ca alloy testified the existence of eutectic structure.

scholarly journals Microstructures and Hydrogen Permeability of Nb-Ti-Ni Alloys with High Resistance to Hydrogen Embrittlement

2005 ◽  
Vol 46 (5) ◽  
pp. 1026-1031 ◽  
Author(s):  
Kunihiko Hashi ◽  
Kazuhiro Ishikawa ◽  
Takeshi Matsuda ◽  
Kiyoshi Aoki
Keyword(s):  
Hydrogen Embrittlement ◽  
High Resistance ◽  
Hydrogen Permeability ◽  
Ni Alloys

THE SYSTEMS Li2SO4–K2SO4–H2O AND Li2SO4–Na2SO4–H2O AT 25 °C.

1958 ◽  
Vol 36 (1) ◽  
pp. 171-175 ◽  
Author(s):  
A. N. Campbell ◽  
E. M. Kartzmark
Keyword(s):  
Solid Solution ◽  
Transition Temperature ◽  
Sodium Sulphate ◽  
Double Salt ◽  
The Other ◽  
Other Hand ◽  
Lithium Sulphate

The 25° isotherm of the system Li2SO4–K2SO4–H2O shows the existence of the double salt, Li2SO4. K2SO4, whereas that of the system Li2SO4–Na2SO4–H2O yields no double salt but extensive solid solution of lithium sulphate in sodium sulphate. On the other hand, a study at 39.5 °C. of the latter system shows that the double salt, Li2SO4. Na2SO4, does form at this temperature, accompanied as before by solid solution of lithium sulphate in sodium sulphate. The transition temperature for the reaction[Formula: see text]is 29.3 °C. A further transition, of unknown nature, occurs between 49° and 57°.

scholarly journals Reactivity of T-Nb2O5 or H-Nb2O5 towards V2O5. Synthesis in the solid state and properties of V4Nb18O55

2009 ◽  
Vol 7 (2) ◽  
pp. 222-227 ◽  
Author(s):  
Piotr Tabero ◽  
Elzbieta Filipek ◽  
Mateusz Piz
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Solid State ◽  
Ir Spectra ◽  
Ir Spectrum ◽  
The Other ◽  
Other Hand ◽  
Structural Relations

AbstractThe IR spectrum of V4Nb18O55 has been compared with the IR spectra of selected niobates of known structures to show structural relations between these compounds. This comparison shows that V4Nb18O55 has crystal structure related to T-Nb2O5, W16Nb18O94 and Ba2NaNb5O15. On the other hand, reaction between V2O5 and H-Nb2O5 yields a solid solution of V2O5 in VNb9O25. It has been proposed two models of synthesized solid solution with formulas V1+xNb9-xO25 or V1+xNb9O25+5x/2.Independently of Nb2O5 polymorph, used for synthesis, the metastable compound VNbO5 cannot be synthesized in the solid state below 650°C

The Role of Arsenic in Preventing the Dezincification of a-Brass

CORROSION ◽  
1969 ◽  
Vol 25 (3) ◽  
pp. 137-146 ◽  
Author(s):  
E. E. LANGENEGGER ◽  
F. P. A. ROBINSON
Keyword(s):  
Solid Solution ◽  
Cathodic Polarization ◽  
The Other ◽  
Clear Cut ◽  
Other Hand ◽  
Total Immersion

Abstract It is demonstrated by means of freely corroding total immersion tests and anodic and cathodic polarization experiments, that small amounts of arsenic in solid solution in α-brass, effectively prevent dezincification even in the most agressive media. On the other hand, the addition of relatively large amounts of arsenic ions to these corrosive solutions has little effect on the rate of dezincification of non-arsenical α-brass. Although a contribution towards a better understanding of the function of arsenic has been made, a clear-cut explanation of the mechanism appears to fall outside the scope of this experimentation.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

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