scholarly journals Computer simulation of grain growth kinetics with solute drag

1999 ◽  
Vol 14 (3) ◽  
pp. 1113-1123 ◽  
Author(s):  
D. Fan ◽  
S. P. Chen ◽  
Long-Qing Chen
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Driving Force ◽  
Boundary Energy ◽  
Solute Drag ◽  
Lattice Diffusion ◽  
Diffuse Interface ◽  
Growth Exponent ◽  
Grain Growth Kinetics

The effects of solute drag on grain growth kinetics were studied in two-dimensional (2D) computer simulations by using a diffuse-interface field model. It is shown that, in the low velocity/low driving force regime, the velocity of a grain boundary motion departs from a linear relation with driving force (curvature) with solute drag. The nonlinear relation of migration velocity and driving force comes from the dependence of grain boundary energy and width on the curvature. The growth exponent m of power growth law for a polycrystalline system is affected by the segregation of solutes to grain boundaries. With the solute drag, the growth exponent m can take any value between 2 and 3, depending on the ratio of lattice diffusion to grain boundary mobility. The grain size and topological distributions are unaffected by solute drag, which are the same as those in a pure system.

Grain growth kinetics and microstructures of the high Tc GdBa2Cu3O7−δ superconductor

1992 ◽  
Vol 7 (12) ◽  
pp. 3194-3201 ◽  
Author(s):  
M.W. Shin ◽  
T.M. Hare ◽  
A.I. Kingon ◽  
C.C. Koch
Keyword(s):  
Aspect Ratio ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Boundary Energy ◽  
Growth Exponent ◽  
Second Phase ◽  
High Tc ◽  
Microstructure Observation ◽  
Grain Aspect Ratio ◽  
Grain Growth Kinetics

Grain growth in the GdBa2Cu3O7−δ high Tc superconductor was investigated. The composition Gd1.09Ba1.91Cu3O7−δ, within the solid solubility region, was selected for the present grain growth study. Differential thermal analysis did not reveal any thermal event except the incongruent melting point, which is indicative of the absence of a liquid second phase during grain growth. The final densities of isothermally annealed samples ranged from 91.3% to 93.7% of theoretical density. The microstructure observation showed a greater grain aspect ratio in this material than in YBa2Cu3O7−δ. The average grain aspect ratio was about 4.7. A very low grain growth exponent of 0.07 was found in the isothermal annealing temperature range from 965 °C to 1020 °C. By comparison with the results on the YBa2Cu3O7−δ system previously reported, it was concluded that the grain growth kinetics in these materials are strongly controlled by the anisotropy of the grain boundary energy. The activation energy of grain growth was calculated to be about 77 kJ/mole.

Grain growth kinetics and microstructure in the high Tc YBa2Cu3O7−δ superconductor

1991 ◽  
Vol 6 (10) ◽  
pp. 2026-2034 ◽  
Author(s):  
M.W. Shin ◽  
T.M. Hare ◽  
A.I. Kingon ◽  
C.C. Koch
Keyword(s):  
Aspect Ratio ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Weak Link ◽  
Boundary Energy ◽  
Critical Currents ◽  
Growth Exponent ◽  
High Anisotropy ◽  
Significant Difference ◽  
Grain Growth Kinetics

The grain growth and microstructure development of YBa2Cu3O7−δ have been investigated utilizing two different starting particle size distributions (normal and bimodal). The grain growth exponent, n, was found to be about 0.21 for both normal and bimodal samples. An activation energy of 125 kJ/mole was calculated. The low value of n might be attributed to the high anisotropy of grain boundary energy in this system. Samples made from the bimodal powder were found to accelerate grain growth without introducing abnormal grain growth. Although most of the samples attained fractional densities greater than 0.95, the presence of various amounts of porosity (particularly in the case of the bimodal starting powder) did not affect the growth kinetics. The measured aspect ratio of grains did not significantly change during growth. A significant difference in aspect ratio was measured between samples made from the two different starting powders. Critical currents ranged from 10 to 120 A/cm2, but no concrete relationship with grain size was established. This implies that the grains produced by this experiment were in the size range where other factors, presumably microcracking, severely limited the current carrying capacity by the weak link effect.

Grain boundary energy, disordering energy and grain growth kinetics in nanocrystalline MgAl2O4 spinel

2018 ◽  
Vol 149 ◽  
pp. 302-311 ◽  
Author(s):  
Dereck N.F. Muche ◽  
Maxwell A.T. Marple ◽  
Sabyasachi Sen ◽  
Ricardo H.R. Castro
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Boundary Energy ◽  
Grain Boundary Energy ◽  
Mgal2o4 Spinel ◽  
Grain Growth Kinetics

Diffusion Controlled Abnormal Grain Growth in Ceramics

2007 ◽  
Vol 558-559 ◽  
pp. 1227-1236 ◽  
Author(s):  
Shen J. Dillon ◽  
Martin P. Harmer
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Abnormal Grain Growth ◽  
Growth Theory ◽  
Diffusion Controlled ◽  
Grain Growth Kinetics ◽  
Kinetics Of

The grain growth kinetics of silica and calcia doped alumina at 1400oC and their grain boundary complexion is characterized. These data are compared to predictions of both diffusion controlled and nucleation limited interface controlled grain growth theory. It is deduced from the indicators that the mechanism for normal and abnormal grain growth in these aluminas is diffusion controlled.

Grain Growth in Nb-Alloyed Stainless Steel of AISI 347 during Heating

2013 ◽  
Vol 753 ◽  
pp. 345-348 ◽  
Author(s):  
Hai Wen Luo ◽  
Han Dong ◽  
Ling Feng Chen
Keyword(s):  
Activation Energy ◽  
Stainless Steel ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Isothermal Holding ◽  
Growth Exponent ◽  
Microalloyed Steels ◽  
Nb Content ◽  
Grain Growth Kinetics ◽  
Kinetics Of

Grain growth kinetics in an AISI 347 stainless steel with Nb content up to 0.7%wt was studied during the isothermal holding in the temperature range of 1100-1270°C for various periods. Abnormal grain growth was observed even in the presence of a large amount of precipitates. The kinetics of normal grain growth was tracked by metallographic measurements and fitted by the classical modeling, which led to two important parameters of activation energy Q and growth exponent n derived. Both of them are larger than the usual values for grain growth in the Nb-microalloyed steels due to the much larger content of Nb in the present steel.

scholarly journals Grain Boundary Properties and Grain Growth: Al Foils, Al Films

2004 ◽  
Vol 819 ◽  
Author(s):  
Katayun Barmak ◽  
Wayne E. Archibald ◽  
Anthony D. Rollett ◽  
Shlomo Ta'asan ◽  
David Kinderlehrer
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Misorientation Angle ◽  
Driving Forces ◽  
Boundary Energy ◽  
Orientation Imaging Microscopy ◽  
Solute Drag ◽  
Grain Structure ◽  
Two Dimensional

AbstractRelative grain boundary energy as a function of misorientation angle has been measured in cube-oriented, i.e., <100> fiber-textured, 120 [.proportional]m-thick Al foil using orientation imaging microscopy and a statistical multiscale method. The energies of low-angle boundaries increase with misorientation angle, in good agreement with the Read-Shockley model. The relative energies of high-angle boundaries exhibit little variation with misorientation. Examination of the grain structure of <111> fiber-textured, 100 nm-thick Al films annealed at 400°C for 0.5-10 h shows 5 and 6 sided grains to be the most frequent, and the fraction of four-sided grains to be significant. The mean number of sides is slightly lower than the expected value of 6 for two- dimensional structures. Of lognormal, gamma and Rayleigh distributions, gamma gives the best fit to the grain size data in the films; however, the difference between gamma and lognormal is small. Grain growth is not self-similar and stagnates after one hour of annealing. The evolution of the grain size distribution with time indicates that the growth stagnation in the films is neither consistent with boundary pinning by grooving nor with conventional treatments of solute drag. Surface, elastic-strain and plastic-strain energy driving forces do not play a significant role in the grain growth and the subsequent stagnation since the films are strongly textured even in the as- deposited state. The steady-state distributions of reduced grain area for two-dimensional, Monte Carlo and partial differential equation based simulations show excellent agreement with each other, even when anisotropic boundary energies are used. However, comparison with experimental distributions reveals a significantly higher population of small grains in the experiments.

Grain Growth and the Puzzle of its Stagnation in Thin Films a Detailed Comparison of Experiments and Simulations

2012 ◽  
Vol 715-716 ◽  
pp. 473-479 ◽  
Author(s):  
Katayun Barmak ◽  
Eva Eggeling ◽  
Richard Sharp ◽  
Scott Roberts ◽  
Terry Shyu ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Energy ◽  
Large Body ◽  
Elastic Strain Energy ◽  
Solute Drag ◽  
Detailed Comparison ◽  
Metallic Films ◽  
Five Factors ◽  
Comparison Of Experiments

We revisit grain growth and the puzzle of its stagnation in thin metallic films. We bring together a large body of experimental data that includes the size of more than 30,000 grains obtained from 23 thin film samples of Al and Cu with thicknesses in the range of 25 to 158 nm. In addition to grain size, a broad range of other metrics such as the number of sides and the average side class of nearest neighbors is used to compare the experimental results with the results of two dimensional simulations of grain growth with isotropic boundary energy. In order to identify the underlying cause of the differences between these simulations and experiments, five factors are examined. These are (i) surface energy and elastic strain energy reduction, (ii) anisotropy of grain boundary energy, and retarding and pinning forces such as (iii) solute drag, (iv) grain boundary grooving and (v) triple junction drag. No single factor provides an explanation for the observed experimental behavior.

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