Ostwald ripening kinetics of angular grains dispersed in a liquid phase by two-dimensional nucleation and abnormal grain growth

The grain growth behavior of 0.95(Na0.5Bi0.5)TiO3 –0.05BaTiO3 (mole fraction, NBT–5BT) grains was investigated with excess Bi2O3 addition. The powder compacts of NBT–5BT were sintered at 1200 °C for various sintering times and with various amounts of Bi2O3 (0.1, 1.5, 4.0 and 10.0 mol%). When Bi2O3 was added to round-edged cubic NBT–5BT, the grain shape changed to a more faceted cube and the amount of liquid phase increased during sintering. A more faceted cubic grain shape indicates an increase in the critical driving force for appreciable growth of grains. However, obvious abnormal grain growth did not appear in any of the NBT–5BT samples with excess Bi2O3. The amount of liquid phase increased as the amount of Bi2O3 increased. Therefore, the rate of grain growth could be decreased by the increasing the distance for the diffusion of atoms. These observations allowed us to conclude that the growth of Bi2O3-excess NBT–5BT grains is governed by the growth of facet planes via the two-dimensional nucleation grain growth mechanism during changing grain shape and amount of liquid.

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The Effects of Nb Carbo-Nitride Precipitation Conditions on Abnormal Grain Growth in Nb Added Steels

Materials Science Forum ◽

10.4028/www.scientific.net/msf.539-543.4167 ◽

2007 ◽

Vol 539-543 ◽

pp. 4167-4172 ◽

Cited By ~ 7

Author(s):

Toshio Murakami ◽

Hitoshi Hatano ◽

Yosuke Shindo ◽

Mutsuhiro Nagahama ◽

Hiroshi Yaguchi

Keyword(s):

Grain Growth ◽

Ostwald Ripening ◽

Growth Behavior ◽

Abnormal Grain Growth ◽

Pinning Force ◽

Austenite Grain Size ◽

Austenite Grain ◽

Ripening Rate ◽

Grain Growth Behavior ◽

Nitride Precipitation

In order to investigate the effects of Nb carbo-nitride precipitation conditions on abnormal grain growth behavior during high temperature carburizing, size of Nb carbo-nitride precipitates was controlled by precipitation treatment at 1173-1273K for 0.6-54ks, and the specimens were quasi-carburized at 1323K. Abnormal grain growth was enhanced when the size of Nb precipitates was fine or coarse, so there is a suitable size range in Nb precipitates to suppress abnormal grain growth. The reason why abnormal grain growth was enhanced is the lack of pinning force as the conventional theory proposed by Hillert or Gladman; however, it cannot be explained by this theory that small precipitates promote abnormal grain growth. It is considered that Ostwald ripening rate of precipitates is also an important factor in controlling abnormal grain growth in addition to the amount and size of precipitates and austenite grain size, which were parameters in the Gladman‘s theory on abnormal grain growth behavior.

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Effect of the Liquid-Forming Additive Content on the Kinetics of Abnormal Grain Growth in Alumina

Journal of the American Ceramic Society ◽

10.1111/j.1151-2916.2003.tb03486.x ◽

2003 ◽

Vol 86 (8) ◽

pp. 1421-1423 ◽

Cited By ~ 45

Author(s):

Jung Hyuck Ahn ◽

Je-Hun Lee ◽

Seong-Hyeon Hong ◽

Nong-Moon Hwang ◽

Doh-Yeon Kim

Keyword(s):

Grain Growth ◽

Abnormal Grain Growth ◽

Additive Content ◽

Kinetics Of

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Diffusion Controlled Abnormal Grain Growth in Ceramics

Materials Science Forum ◽

10.4028/www.scientific.net/msf.558-559.1227 ◽

2007 ◽

Vol 558-559 ◽

pp. 1227-1236 ◽

Cited By ~ 19

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.

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On the Validation of the Monte Carlo Technique in Simulation of Grain Growth in Small, Two-Dimensional Systems

Materials Science Forum ◽

10.4028/www.scientific.net/msf.558-559.1087 ◽

2007 ◽

Vol 558-559 ◽

pp. 1087-1092

Author(s):

Ola Hunderi ◽

Knut Marthinsen ◽

Nils Ryum

Keyword(s):

Monte Carlo ◽

Grain Boundary ◽

Grain Growth ◽

Computer Simulations ◽

Two Dimensions ◽

Theoretical Treatment ◽

Two Dimensional ◽

Simulation Techniques ◽

Boundary Curvature ◽

Kinetics Of

The kinetics of grain growth in real systems is influenced by several unknown factors, making a theoretical treatment very difficult. Idealized grain growth, assuming all grain boundaries to have the same energy and mobility (mobility M = k/ρ, where k is a constant and ρ is grain boundary curvature) can be treated theoretically, but the results obtained can only be compared to numerical grain growth simulations, as ideal grain growth scarcely exists in nature. The validity of the simulation techniques thus becomes of great importance. In the present investigation computer simulations of grain growth in two dimensions using Monte Carlo simulations and the grain boundary tracking technique have been investigated and compared in small grain systems, making it possible to follow the evolution of each grain in the system.

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