Hydrogen Diffusion in Metals

Völkl, J.; Alefeld, G.

doi:10.1016/b978-0-12-522660-8.50010-6

Cited by 146 publications

(93 citation statements)

References 223 publications

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“…These include, in addition to derivatives from steady rates of hydrogen permeation across a known concentration gradient and from breakthrough times related to detection of hydrogen at the side of membranes remote from hydrogen introduction q u a s i e l a s t i c n e u t r o n s c a t t e r i n g (29, I 18, I 36,163-1 65,201) and anelastic Gorsky Effect measurements (51,(169)(170)(171)(172)(173). At very low ix phase hydrogen contents, a large measure of agreement now exists between values derived by the various methods (104,202). At 25°C these are of the order of I o -'/cm2/s representing an average value over the narrow a phase range of contents within which the only reported trend has been that of a slight decrease with increasing hydrogen content (86).…”

mentioning

confidence: 85%

Palladium-Hydrogen System

Lewis

Kandasamy²,

Tong³

2000

SSP

262

415

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Characteristic examples of three types of change of form of p n relationships at 2 5 T , as the contents of elements alloying with palladium a r e gradually increased (4,37,70,74-83,95-98,~04,108,153,154), are illustrated in Figure 9. As for the palladiumhydrogen system itself (4), such relationships have been determined from direct equilibrations with hydrogen gas, as well as being derived from measurements of electrode potential. Similarly as for palladium-hydrogen, temperature dependences of the p n relationships have been used to supplement calorimetric data ( I 10) in deriving heats and cntropies of hydrogen absorption, both at initially low values (79)(80)(81)(82)95,100,108) of hydrogen content (n-to) and over (Y =p transition regionsThe sequence of relationships in Figure 9(c) (4,37,70,74-83,'04,I54,I78).shows gradual increases with increasing rhodium content in the range o f n over which (Y and / J ' phases coexist. This sequence now seems unique to the palladium-rhodium-hydrogen system (45,75, I 53,154), since some suggestions of similarities of the palladium-manganesehydrogen system (179) seem doubtful in view of possible incomplete equilibrations.'The remaining families of p n isotherms for palladium alloy-hydrogen systems would thus seem to be divisible into two groups represented by those in Figures 9(a) and 9 (b). In both cases the ranges of n over t i + p phase regions are successively shortened with increasing content of the alloying element, even in the cases of alloys with readily hydride-forming transition or inner transition elements such as vanadium Decreases, in the range of n over (r +/I regions, with increasing amounts of alloying elements, have continued to be deduced from X-ray determinations of and / 3 phase lattice constants for additional palladium alloyhydrogen systems (4,79-82,157, I 80-1 82).Apart from the probable case of the palladium-nickel-hydrogen system (so), these general trends of decreasing extents of ( Y , p coexistence with increasing contents of alloying element are similar to the effects of increasing temperature in the palladium-hydrogen system, being accompanied by decreases in the extents of hystereses of absorption and desorption relationships between hydrogen contents and other experimental parameters (4,69,(96)(97)(98) later, has importance in choices of alloy compositions as hydrogen permeation membranes. In addition to the arguments concerning the solubility of hydrogen in the palladium-silver alloys, the extents of decreases of hydrogen solubilities with increasing contents of other alloying metals have been used (95,104,108) in support of an essentially protonic nature of the hydrogen entities. However, in order to allow for proposed levels of electron donation it has seemed necessary to postulate adoptions of oxidation states by the alloying elements which can be difficult to reconcile with their relative positions in sequence of electronegaiivities.Moreover as for the palladium-hydrogen system, latterly there has been increasing emphasis on the account ...

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confidence: 85%

Palladium-Hydrogen System

Lewis

Kandasamy²,

Tong³

2000

SSP

262

415

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“…The activation energy for diffusion is also assumed to be independent of the mass of the isotope. Diffusion data at subambient temperatures do not support equation 20 for a number of metals [11], however, permeability data at elevated temperatures generally support the inverse square root dependence on mass for nickel [12] and stainless steels [13][14][15][16]. For the purposes of this report we assume that equation 20 is a good approximation for both permeability and diffusivity; implicitly then the solubility is assumed to be independent of the mass of the isotope.…”

Section: Mass/isotope Effectsmentioning

confidence: 99%

10.2172/918137

2000

CrossRef Listing of Deleted DOIs

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“…When this approximation is invoked, the activation energy for diffusion is generally assumed to be independent of the mass of the isotope. Diffusion data at subambient temperatures do not support equation 3 for a number of metals [2], however, at elevated temperatures, the inverse square root dependence on mass generally provides a reasonable approximation (especially for fcc structural metals) [3][4][5][6][7][8][9]. While equation 3 provides a good engineering estimate of the relative diffusivity of hydrogen and its isotopes, more advanced theories have been applied to explain experimental data; for example, quantum corrections and anharmonic effects can account for experimentally observed differences of diffusivity of isotopes compared to the predictions of equation 3 [3,10].…”

Section: Diffusivitymentioning

confidence: 99%

Tritium Barriers and Tritium Diffusion in Fusion Reactors

Causey

Karnesky

Marchi

2012

Comprehensive Nuclear Materials

132

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Tritium and deuterium induce radiation in reactor materials and some radioactive tritium gas may be released. Most of the materials used in fusion reactors are metals that have relatively high permeabilities for tritium. The fusion community has been working on barriers to minimize tritium release. Unfortunately, most barrier materials work very well during laboratory experiments, but fail to meet requirements when placed in radiation environments.This chapter presents tritium permeation characteristics of various materials used in fusion reactors, including plasma-facing, structural, and barrier materials. The necessary parameters for tritium release calculations for various regions of a fusion reactor are given.

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Hydrogen Diffusion in Metals

Cited by 146 publications

References 223 publications

Palladium-Hydrogen System

Palladium-Hydrogen System

10.2172/918137

Tritium Barriers and Tritium Diffusion in Fusion Reactors

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