Grain Boundary Diffusion-Controlled Processes and Properties of Bulk Nanostructured Alloys and Steels

2006 ◽  
Vol 503-504 ◽  
pp. 141-148 ◽  
Author(s):  
Yu.R. Kolobov ◽  
Konstantin Ivanov
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Severe Plastic Deformation ◽  
Boundary Diffusion ◽  
Diffusion Processes ◽  
Grain Boundary Diffusion ◽  
Controlled Processes ◽  
Bioactive Coating ◽  
Diffusion Controlled ◽  
Theoretical Investigations

The experimental and theoretical investigations of grain boundary diffusion processes have been performed using metals and alloys in nanostructured state produced by severe plastic deformation and the respective polycrystalline counterparts. The main features of diffusioncontrolled mechanisms of plastic deformation observed by the creep of nanostructured metals are considered. The use of severe plastic deformation treatment and of the effect of activation of diffusion-controlled processes for enhancing the properties of nanostructured steels and alloys designed for engineering and medical applications (nanostructured titanium-bioactive coating composite included) is described and examples are offered.

Modern Models of Grain Boundary Diffusion

2011 ◽  
Vol 312-315 ◽  
pp. 1116-1125
Author(s):  
Vladimir V. Popov
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Severe Plastic Deformation ◽  
Nanocrystalline Materials ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Coarse Grained ◽  
Gas Condensation ◽  
Non Equilibrium

Recent models of grain-boundary diffusion are briefly reviewed. Models of diffusion along equilibrium boundaries of recrystallization origin in coarse-grained materials and along non-equilibrium boundaries in nanocrystalline materials obtained by gas condensation and compacting or by severe plastic deformation are considered separately.

scholarly journals Determination of Grain Boundary Diffusion Coefficients in C-Regime by Hwang-Balluffi Method: Silver Diffusion in Pd

2009 ◽  
Vol 289-292 ◽  
pp. 763-767 ◽  
Author(s):  
Z. Balogh ◽  
Z. Erdélyi ◽  
Dezső L. Beke ◽  
Alain Portavoce ◽  
Christophe Girardeaux ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Diffusion Coefficients ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Controlled Processes ◽  
Diffusion Controlled ◽  
Arrhenius Function ◽  
Data Points ◽  
Accumulation Kinetics

Diffusion controlled processes play a crucial role in the degradation of technical materials. At low temperatures the most significant of them is the diffusion along grain boundaries. In thin film geometry one of the best methods for determining the grain boundary (GB) diffusion coefficient of an impurity element is the Hwang-Balluffi method, in which a surface sensitive technique is used to follow the surface accumulation kinetics. Results of grain boundary diffusion measurements, carried out in our laboratory by this method in three different materials systems (Ag/Pd, Ag/Cu and Au/Ni) are reviewed. In case of Ag diffusion along Pd GBs the surface accumulation was followed by AES method. The data points can be well fitted by an Arrhenius function with an activation energy Q=0.99eV

The State of Grain Boundaries and Grain-Boundary Diffusion in Ultrafine-Grained Mo Obtained by Severe Plastic Deformation

2016 ◽  
Vol 367 ◽  
pp. 130-139 ◽  
Author(s):  
Vladimir V. Popov ◽  
A.V. Sergeev
Keyword(s):  
Plastic Deformation ◽  
High Pressure ◽  
Grain Boundary ◽  
Severe Plastic Deformation ◽  
Grain Boundaries ◽  
Boundary Diffusion ◽  
High Pressure Torsion ◽  
Grain Boundary Diffusion ◽  
Fast Diffusion ◽  
Non Equilibrium

The grain-boundary diffusion of Co in ultra-fine grained Mo processed by high-pressure torsion has been studied by emission Mössbauer spectroscopy and radio-tracer analysis. It is demonstrated that under the severe plastic deformation by high-pressure torsion the non-equilibrium grain boundaries are formed which are the ultra-fast diffusion paths. At annealing in the temperature range of 623-823 K the relaxation of the non-equilibrium boundaries proceeds and their properties approach to those of equilibrium boundaries of recrystallization origin.

Grain-boundary diffusion of nickel in submicrocrystalline molybdenum processed by severe plastic deformation

2008 ◽  
Vol 34 (2) ◽  
pp. 136-138 ◽  
Author(s):  
G. P. Grabovetskaya ◽  
I. P. Mishin ◽  
I. V. Ratochka ◽  
S. G. Psakhie ◽  
Yu. R. Kolobov
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Severe Plastic Deformation ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion

Grain-Boundary Diffusion of 57Co in Ultrafine Nickel after Severe Plastic Deformation

2021 ◽  
Vol 122 (10) ◽  
pp. 976-980
Author(s):  
E. V. Osinnikov ◽  
S. A. Murzinova ◽  
A. Yu. Istomina ◽  
V. V. Popov ◽  
A. V. Stolbovskiy ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Severe Plastic Deformation ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Ultrafine Nickel

Intergranular Coupling and Grain Isolation of Thin Co Films

1998 ◽  
Vol 517 ◽  
Author(s):  
Heng Gong ◽  
Wei Yang ◽  
David N. Lambeth ◽  
David E. Laughlin
Keyword(s):  
Grain Boundary ◽  
Thermal Instability ◽  
Boundary Diffusion ◽  
Oxidation Process ◽  
Diffusion Processes ◽  
Narrow Range ◽  
Grain Boundary Diffusion ◽  
Temperature Dependent ◽  
In Situ Diffusion

AbstractThe effects of rapid oxidation and overcoat diffusion processes on the intergranular coupling and grain isolation in thin Co films were studied. The oxidation process was found to be strongly temperature dependent. The optimal coercivities can only be achieved within a narrow range of temperatures, while further increasing the temperature incurs significant thermal instability. CrMn underlayers were confirmed to be more effective in enhancing the grain isolation by the grain boundary diffusion during the oxidation process. The oxidation process does not change the Co anisotropy, and hence the coercivity increase is appears to be a result of better grain isolation. The in-situ diffusion of Ag and Cr overcoats were also found to have siginificant effects on the grain isolation in Co and CoCr films.

Mechanistic Two Stage Fission Gas Release Model

2002 ◽  
Author(s):  
Yong-Soo Kim ◽  
Chan-Bok Lee
Keyword(s):  
Grain Boundary ◽  
Diffusion Coefficients ◽  
Boundary Diffusion ◽  
Diffusion Processes ◽  
Lattice Diffusion ◽  
Grain Boundary Diffusion ◽  
Factor Α ◽  
Two Stages ◽  
Grain Surface ◽  
Release Model

In this study, a mechanistic two stages model is developed which analytically simulates the two-step diffusion processes, grain lattice diffusion and grain boundary diffusion, coupled with the bubbles trap/resolution. Mathematical manipulation reveals that the release at high burn-up depend on the ratio of the diffusivities in the both processes, i.e., α ≅ Dveff/Dgbeff where Dveff and Dgbeff are effective volume and grain boundary diffusion coefficients, respectively. Thus, the ratio α is incorporated in the time-dependent third kind boundary condition at the equivalent grain surface. This model brings forth analytical solutions of the fractional release which are identical to that of either ANS5.4 or modified ANS5.4 model when α goes to the infinity. It turns out that this model describes the release behavior well in the high burn-up fuel and puts out a comparable prediction to the solution of FRAPCON-3 model under the same condition. It is also demonstrated that the new factor α not only ease the computational treatment for the high burn-up fuel performance evaluation, but also enables us to possibly separate the burn-up enhancement from the diffusion coefficients and to easily simulate the bubble-related phenomena in the grain boundary.

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