Determination of diffusion characteristics of the volume and boundary components of the flow of hydrogen in polycrystalline metals

1975 ◽  
Vol 9 (1) ◽  
pp. 50-54 ◽  
Author(s):  
V. M. Sidorenko ◽  
I. I. Sidorak
Keyword(s):  
Polycrystalline Metals ◽  
Diffusion Characteristics

Models of lithium transport as applied to determination of diffusion characteristics of intercalation electrodes

2017 ◽  
Vol 53 (7) ◽  
pp. 706-712 ◽  
Author(s):  
A. V. Ivanishchev ◽  
A. V. Churikov ◽  
I. A. Ivanishcheva ◽  
A. V. Ushakov ◽  
M. J. Sneha ◽  
...  
Keyword(s):  
Lithium Transport ◽  
Diffusion Characteristics ◽  
Intercalation Electrodes

Effect of Pile-Up on Nanoindentation Measurements of Polycrystalline Bulk Metals

2013 ◽  
Vol 853 ◽  
pp. 143-150 ◽  
Author(s):  
Reza A. Mirshams ◽  
Ashish K. Srivastava
Keyword(s):  
Grain Orientation ◽  
Electron Backscatter Diffraction ◽  
Surface Probe ◽  
Polycrystalline Metals ◽  
Pile Up ◽  
Electron Backscatter ◽  
Ebsd Technique ◽  
Backscatter Diffraction ◽  
Scanning Electron

This paper presents the results of an experimental investigation on the effects of orientation and grain size on nanoindentation measurements of hardness and modulus of elasticity for three polycrystalline metals: copper, nickel, and iron. Three geometrically different indenter tips were used, and the pile-ups were characterized with a surface probe instrument. The electron backscatter diffraction (EBSD) technique and a scanning electron microscope (SEM) were used to characterize grain orientation and microstructure. It was found that additional contact areas due to pile-ups have a significant effect on determination of mechanical properties by the nanoindenter.

Tightly bound water in smectites

2017 ◽  
Vol 102 (5) ◽  
pp. 1073-1090 ◽  
Author(s):  
Artur Kuligiewicz ◽  
Arkadiusz Derkowski
Keyword(s):  
Bound Water ◽  
Interlayer Cation ◽  
Octahedral Sheet ◽  
Isothermal Tg ◽  
Hydration Enthalpy ◽  
Diffusion Characteristics ◽  
Model Independent ◽  
Isothermal Drying ◽  
And Diffusion

Abstract Smectites are able to retain molecular tightly bound water (TBW) at temperatures above 100 °C, even after prolonged drying. The presence of TBW affects the stable isotope ratios, the dehydroxylation behavior of smectites and smectite-rich samples and also has implications in measuring various properties of clay-rich rocks. Five reference smectites, in Mg-, Ca-, Na-, and Cs-exchanged forms were subjected to different drying protocols followed by the determination of TBW contents using precise thermogravimetric (TG) analysis. Activation energies (Ea) of the removal of different water fractions at temperatures up to 1000 °C were determined in non-isothermal TG experiments using model-independent methods. Additionally, 4A and 13X zeolites were examined in both cases as apparent OH-free references. After drying at 110 °C, all smectites still contained up to 3 water molecules per interlayer cation. The TBW contents in smectites were found to be primarily dependent on the isothermal drying temperature. For a given temperature, TBW contents decreased with respect to the type of interlayer cation in the following order: Mg > Ca > Na > Cs. The influence of the time of drying and the smectite layer charge were found to be negligible. The Ea of dehydration below 100 °C, as determined by the Friedman method, was quite constant within the 45–60 kJ/mol range. The Ea of TBW removal increased along with the degree of reaction from 90 to 180 kJ/mol, while the Ea of dehydroxylation was found in the 159–249 kJ/mol range, highly depending on the sample’s octahedral sheet structure and the interlayer cation. The Mg2+ cation can hold H2O molecules even beyond 550 °C, making it available during dehydroxylation or—for geologic-scale reactions—pass H2O to metamorphic conditions. High similarities between the TBW contents and the Ea of dehydration for smectites and cationic (low Si/Al-) zeolites lead to the conclusion that TBW in smectites is remarkably similar to zeolitic water in terms of cation bonding and diffusion characteristics. The optimal drying protocol for smectites is to substitute interlayer cations with cations of a low-hydration enthalpy, such as Cs, and to dry a sample at 300 °C, provided that the sample is Fe-poor. Fe-rich smectites should be dried at 200 °C to avoid dehydroxylation that occurs below 300 °C.

Texture and stress determination in metals by using ultrasonic Rayleigh waves and neutron diffraction

1986 ◽  
Vol 320 (1554) ◽  
pp. 187-200 ◽  
Keyword(s):  
Neutron Diffraction ◽  
Rayleigh Wave ◽  
Internal Stress ◽  
Wave Velocity ◽  
Plastic Anisotropy ◽  
Rolled Plate ◽  
Stress Determination ◽  
Rayleigh Wave Velocity ◽  
Polycrystalline Metals

Polycrystalline metals often contain significant levels of texture and internal stress. Plastic anisotropy originates from the texture or crystallographic alignment and can affect the formability of the metal, whereas the presence of internal stress can seriously limit the lifetime of a component. In the presence of either texture or stress, the ultrasonic velocity in the material depends on the propagation and polarization directions, and there is considerable interest in exploiting this anisotropy for non-destructive texture and stress determination. In this paper an analytical expression for the angular dependence of the Rayleigh-wave velocity in polycrystalline metals with small anisotropy typical of rolled plate is given. It is shown that surface-wave velocity measurements can be combined with the normal shear-wave birefringence technique to give a texture-independent determination of the difference in principal stresses in the plane of the plate. The theory is tested by comparing ultrasonic measurements on two aluminium plates with the behaviour predicted by using a neutron diffraction determination of the crystallite orientation distribution function. The possibility of obtaining the depth profile from the frequency dependence of the Rayleigh-wave velocity is considered.

Determination of Diffusion Characteristics of Intact Rock Mass: A Critical Evaluation

2008 ◽  
Vol 31 (6) ◽  
pp. 101514
Author(s):  
L. D. Suits ◽  
T. C. Sheahan ◽  
B. Hanumantha Rao ◽  
D. N. Singh
Keyword(s):  
Rock Mass ◽  
Critical Evaluation ◽  
Intact Rock ◽  
Diffusion Characteristics ◽  
Intact Rock Mass
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