Interpretation of grain boundary grooving data for combined surface and volume diffusion

1975 ◽  
Vol 6 (8) ◽  
pp. 1653-1654 ◽  
Author(s):  
W. M. Robertson ◽  
S. R. Srinivasan
Keyword(s):  
Grain Boundary ◽  
Volume Diffusion

Mesoscale Simulations of Microstructure Evolution in a Temperature Gradient

2010 ◽  
Vol 1264 ◽  
Author(s):  
Bala Radhakrishnan ◽  
Gorti Sarma
Keyword(s):  
Temperature Gradient ◽  
Grain Boundary ◽  
Pore Size ◽  
Microstructure Evolution ◽  
Volume Diffusion ◽  
Grain Structure ◽  
Migration Direction ◽  
Boundary Force ◽  
Mesoscale Simulations ◽  
Model Approach

AbstractThe evolution of pore and grain structure in a nuclear fuel environment is strongly influenced by the local temperature, and the temperature gradient. The evolution of pore and grain structure in an externally imposed temperature gradient is simulated for a hypothetical material using a Potts model approach that allows for porosity migration by mechanisms similar to surface, grain boundary and volume diffusion, as well as the interaction of migrating pores with stationary grain boundaries. First, the migration of a single pore in a single crystal in the presence of the temperature gradient is simulated. Next, the interaction of a pore moving in a temperature gradient with a grain boundary that is perpendicular to the pore migration direction is simulated in order to capture the force exerted by the pore on the grain boundary. The simulations reproduce the expected variation of pore velocity with pore size as well as the variation of the grain boundary force with pore size.

Effect of Strong Magnetic Field on the Discontinuous and Continuous Precipitation in AZ91 Mg Alloy

2005 ◽  
Vol 488-489 ◽  
pp. 849-852 ◽  
Author(s):  
Jie Dong ◽  
Z.F. Li ◽  
Xiao Qing Zeng ◽  
Chen Lu ◽  
Wen Jiang Ding
Keyword(s):  
Magnetic Field ◽  
Grain Boundary ◽  
Aging Process ◽  
Volume Diffusion ◽  
Discontinuous Precipitation ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Az91 Magnesium Alloy ◽  
Continuous Precipitation ◽  
Az91 Magnesium

A strong static magnetic field (SSMF) of about 10 T was introduced to the aging process of AZ91 magnesium alloy. Comparing with conventional aging, in the first stage of aging with SSMF, discontinuous precipitation of Mg17Al12 at grain boundary was accelerated. The magnetically induced grain boundary migration might be responsible for this acceleration effect. The density of the Mg17Al12 continuous precipitates inside the grains was increased and the precipitation plates became thinner in SSMF pre-aged specimens, which might be ascribed to the retarded volume diffusion resulted from the SSMF.

SELF-DIFFUSION IN POLYCRYSTALLINE NICKEL

1959 ◽  
Vol 37 (10) ◽  
pp. 1623-1628 ◽  
Author(s):  
J. R. MacEwan ◽  
J. U. MacEwan ◽  
L. Yaffe
Keyword(s):  
Grain Boundary ◽  
Boundary Diffusion ◽  
Volume Diffusion ◽  
Grain Boundary Diffusion ◽  
The Self ◽  
Polycrystalline Nickel ◽  
Self Diffusion ◽  
Diffusion Studies

The self-diffusion of nickel has been studied in polycrystalline samples by a sectioning technique. There is evidence of grain boundary diffusion below temperatures of 1150 °C. The results obtained between 1150° and 1400 °C are representative of volume diffusion and are represented by the expression[Formula: see text]A comparison is made with the results of other self-diffusion studies using Zener's hypothesis.

Zinc Self-Diffusion in ZnO

2005 ◽  
Vol 237-240 ◽  
pp. 163-168 ◽  
Author(s):  
M.A.N. Nogueira ◽  
Antônio Claret Soares Sabioni ◽  
Wilmar Barbosa Ferraz
Keyword(s):  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Diffusion Coefficients ◽  
Boundary Diffusion ◽  
Volume Diffusion ◽  
Grain Boundary Diffusion ◽  
Polished Surface ◽  
Self Diffusion ◽  
Zinc Diffusion ◽  
Diffusion Profiles

This work deals with the study of zinc self-diffusion in ZnO polycrystal of high density and of high purity. The diffusion experiments were performed using the 65Zn radioactive isotope as zinc tracer. A thin film of the tracer was deposited on the polished surface of the samples, and then the diffusion annealings were performed from 1006 to 1377oC, in oxygen atmosphere. After the diffusion treatment, the 65Zn diffusion profiles were established by means of the Residual Activity Method. From the zinc diffusion profiles were deduced the volume diffusion coefficient and the product dDgb for the grain-boundary diffusion, where d is the grain-boundary width and Dgb is the grain-boundary diffusion coefficient. The results obtained for the volume diffusion coefficient show good agreement with the most recent results obtained in ZnO single crystals using stable tracer and depth profiling by secondary ion mass spectrometry, while for the grain-boundary diffusion there is no data published by other authors for comparison with our results. The zinc grain-boundary diffusion coefficients are ca. 4 orders of magnitude greater than the volume diffusion coefficients, in the same experimental conditions, which means that grain-boundary is a fast path for zinc diffusion in polycrystalline ZnO.

Experimental and Theoretical Study of Type-C Grain Boundary and Volume Diffusion by AES in Metal/Metal Structures

2001 ◽  
Vol 194-199 ◽  
pp. 1161-1166
Author(s):  
Z. Erdélyi ◽  
Christophe Girardeaux ◽  
Jean Bernardini ◽  
Dezső L. Beke ◽  
Andree Rolland
Keyword(s):  
Grain Boundary ◽  
Theoretical Study ◽  
Volume Diffusion ◽  
Metal Structures ◽  
Metal Metal ◽  
Type C

Grain boundary and volume diffusion experiments in yttrium aluminium garnet bicrystals at 1,723 K: a miniaturized study

2011 ◽  
Vol 162 (4) ◽  
pp. 739-749 ◽  
Author(s):  
Katharina Marquardt ◽  
Elena Petrishcheva ◽  
Emmanuel Gardés ◽  
Richard Wirth ◽  
Rainer Abart ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Volume Diffusion ◽  
Yttrium Aluminium Garnet ◽  
Yttrium Aluminium

Measurement of the Impurity Diffusivity of Cu in Fe by Laser Induced Breakdown Spectrometry

2005 ◽  
Vol 237-240 ◽  
pp. 266-270 ◽  
Author(s):  
Chan Gyu Lee ◽  
Jung Han Lee ◽  
Byeong Seon Lee ◽  
Yong Ill Lee ◽  
Toshitada Shimozaki ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Diffusion Coefficients ◽  
Boundary Diffusion ◽  
Volume Diffusion ◽  
Diffusion Mechanism ◽  
Grain Boundary Diffusion ◽  
Impurity Diffusion ◽  
Boundary Diffusion Coefficient ◽  
Laser Induced Breakdown ◽  
Good Agreement

The impurity diffusion coefficients of Cu in Fe have been determined in the temperature range of 1073 - 1163 K by means of Laser Induced Breakdown Spectrometry (LIBS). The volume diffusion coefficients for Cu impurity diffusion in a-iron found in this work are in good agreement with the previously published result. The grain boundary diffusion coefficient gb D s d was also calculated using the volume diffusivity and processing the tails of the measured profiles. The values of the activation energy for volume and grain boundary diffusion were approximately 280 and 161 kJmol-1, respectively. This indicates the possibility of a monovacancy diffusion mechanism in case of volume diffusion. The results for the diffusion coefficients are Dv= 2.2 ×10-2exp(-280 kJmol-1/RT) m2s-1 and gb D s d = 2.6 ×10-11exp(-161 kJmol-1/RT) m3s-1.

Analysis of Possibilities of Fisher’s Model Development

2008 ◽  
Vol 138 ◽  
pp. 133-144 ◽  
Author(s):  
Vladimir V. Popov
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Layers ◽  
Low Temperatures ◽  
Volume Diffusion ◽  
Model Development ◽  
Equilibrium Composition ◽  
Experimental Results ◽  
Classical Form ◽  
Mössbauer Studies

The possibilities of Fisher’s model development and generalization are considered, as this model in its classical form contradicts some experimental results. Particularly, it does not explain such a phenomenon, observed in Mössbauer studies, as the transfer of grain-boundary diffusing atoms into near-boundary crystallite areas at temperatures when the volume diffusion is admittedly frozen. Different models explaining this phenomenon are briefly reviewed, the greatest attention being paid to a model accounting for the presence of equilibrium-composition near-boundary layers. It is demonstrated that based on the results of grain boundaries investigations one can conclude that at relatively low temperatures (< 0.35 – 0.40 Tm) the diffusant pumping from a grain boundary proceeds much faster than volume diffusion, and possible reasons for that are considered.

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