Diffusion Processes

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Diffusion Processes


processes that occur during the displacement of the smallest particles of matter (atoms, ions, and molecules) or of their complexes because of the tendency toward an equilibrium distribution of the migrating particle concentrations within a given volume.

The exchange of particles between materials in different states of aggregation may take place during diffusion processes—that is, the phenomena of adsorption and desorption, solution and crystallization, and drying may occur. Diffusion processes also form the basis of such industrial operations as powder sintering (for example, in powder metallurgy), thermal treatment of metals, chemical-thermal treatment of metals (case hardening and nitriding), homogenization of alloys, and diffusion coating. The importance of diffusion processes increases in connection with the necessity of producing special materials for the developing areas of technology, such as atomic power engineering and space travel. Knowledge of the relationships governing the diffusion processes makes it possible to avoid undesirable changes in structures that occur under the influence of high temperatures, large loads, and irradiation.


Liubov, B. Ia. Kineticheskaia teoriia fazovykh prevrashchenii. Moscow, 1969.


References in periodicals archive ?
Diffusion processes (gap formation and movement) take place on the surfaces or in the bodies.
That diffusion processes in facing with SPD occur at larger depths is also indicated by the distribution of microhardness over the surface layer depth, which is nonmonotonic.
By forcing both the reaction and diffusion processes to occur within an inert, porous gel such as polyacrylamide, Swinney's team calmed the convective mixing, stirring and other pattern-killing movements that plague both open and closed reactors.
Advanced Diffusion Processes and Phenomena: Special Topic Volume
Applied diffusion processes from engineering to finance.
The 34 papers invited to this volume describe phase transformations, non-diffusion transformations, the thermodynamics of solid state transformations, and the diffusion processes that control the kinetics of diffusive transformations in the bulk and close to interfaces.
As a result of the direct contact that comes about between the two phases, undesirable nitrogen dissolution and diffusion processes take place within the polymer during the injection phase particularly when the gas is injected in.
This first volume presents papers on such topics as a morphology of diffusion zone from entropy production calculations, hollow hemisphere shell formation by pure Kirkendall porosity, grain boundary diffusion and grain boundary segregation in metals and alloys, defects and sintering-induced diffusion processes in yttria-stabilized zirconia nanomaterials studied by positron annihilation spectroscopy, and peculiarities of structure and texture of high-strength copper-niobium composites.
After an introductory chapter by the editors, 14 contributions are arranged in sections pertaining to the small, internationalizing firm, the large multinational enterprise, and the effects of innovation and knowledge diffusion processes in multinational enterprises.
This work collects numerous abstracts of papers on topics in ceramics, such as carbon and carbides, nitrides, oxides, silicates, diffusion processes, point defects, linear defects, and ionic conduction.

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