Study of Grain Growth in a Ni-Based Superalloy by Experiments and Cellular Automaton Model

The grain growth behavior in a typical Ni-based superalloy was investigated using isothermal heat treatment experiments over a holding temperature range of 1353–1473 K. The experimental results showed that the grain structure continuously coarsened as the holding time and holding temperature increased during heat treatment. A classical parabolic grain growth model was used to explore the mechanism of grain growth under experimental conditions. The grain growth exponent was found to be slightly above 2. This indicates that the current grain growth in the studied superalloy is mainly governed by grain boundary migration with a minor pinning effect from the precipitates. Then, the grain growth in the studied superalloy during isothermal heat treatment was modelled by a cellular automaton (CA) with deterministic state switch rules. The microscale kinetics of grain growth is described by the correlation between the moving velocity and curvature of the grain boundary. The local grain boundary curvature is well evaluated by a template disk method. The grain boundary mobility was found to increase with increasing temperature. The relationship between the grain boundary mobility and temperature has been established. The developed CA model is capable of capturing the dependence of the grain size on the holding time under different holding temperatures.

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Grain Growth Behavior of Al2O3 Nanomaterials: A Review

Materials Science Forum ◽

10.4028/www.scientific.net/msf.653.87 ◽

2010 ◽

Vol 653 ◽

pp. 87-130 ◽

Cited By ~ 12

Author(s):

Ankur Gupta ◽

Samir Sharma ◽

Milind R. Joshi ◽

Parnika Agarwal ◽

Kantesh Balani

Keyword(s):

Grain Boundary ◽

Grain Growth ◽

Electrochemical Corrosion ◽

Secondary Reinforcement ◽

Effect Of Temperature ◽

Growth Exponent ◽

Boundary Mobility ◽

Corrosion Properties ◽

Grain Boundary Mobility

Emergence of engineering nanomaterials to render exceptional properties require understanding the thermodynamics and kinetics of grain growth and eliciting role of grain boundary mobility therein. Grain boundary mobility in alumina (Al2O3) has shown several repercussions on the evolution of microstructure to render drastic differences in the mechanical- (hardness, yield strength), optical- (transmittance), electrical- (conductivity), magnetic- (susceptibility), and electrochemical- (corrosion) properties. Consequently, the role of surface energy and the effect of temperature in equilibrating the grain shape and size are presented herewith. Several statistical or deterministic computational modeling have been attempted by researchers to elicit the dominating grain growth mechanisms. But, the limitations extend from the memory of computer and number of atoms in a simulation, or feeding the boundary conditions without incorporation of the initial microstructure to arrive at the dominating growth mechanism parameters. Contrastingly, the role of dopants in Al2O3 to either enhance or impede the grain growth is presented via various complexions responsible for transitions at the grain boundary interface. Six complexions resulting various grain boundary interface, strongly affect the grain boundary mobility, and sideline the dopant contributions in deciding the overall grain boundary mobility. It has also been presented that grain growth exponent increases with decreasing grain size, and additionally, secondary reinforcement of carbon nanotube (CNT) in Al2O3 impedes the grain mobility by as much as four times. The effect of temperature is found to be more pronounced, and has shown to enhance the grain boundary mobility by as much as six orders of magnitude.

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The Influence of Mg-Based Inclusions on the Grain Boundary Mobility of Austenite in SS400 Steel

Metals ◽

10.3390/met9030370 ◽

2019 ◽

Vol 9 (3) ◽

pp. 370

Author(s):

Chih-Ting Lai ◽

Hsuan-Hao Lai ◽

Yen-Hao Su ◽

Fei-Ya Huang ◽

Chi-Kang Lin ◽

...

Keyword(s):

Grain Boundary ◽

Grain Growth ◽

High Temperatures ◽

Growth Curves ◽

Solute Drag ◽

Grain Structure ◽

Growth Equation ◽

Boundary Mobility ◽

Grain Boundary Mobility ◽

Boundary Velocity

In this study, the effects of the addition of Mg to the grain growth of austenite and the magnesium-based inclusions to mobility were investigated in SS400 steel at high temperatures. A high-temperature confocal scanning laser microscope (HT-CSLM) was employed to directly observe, in situ, the grain structure of austenite under 25 torr Ar at high temperatures. The grain size distribution of austenite showed the log-normal distribution. The results of the grain growth curves using 3D surface fitting showed that the n and Q values of the growth equation parameters ranged from 0.2 to 0.26 and from 405 kJ/mole to 752 kJ/mole, respectively, when adding 5.6–22 ppm of Mg. Increasing the temperature from 1150 to 1250 °C for 20 min and increasing the addition of Mg by 5.6, 11, and 22 ppm resulted in increases in the grain boundary velocity. The effects of solute drag and Zener pinning on grain boundary mobility were also calculated in this study.

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The effect of solutes on grain boundary mobility during recrystallization and grain growth in some single-phase aluminium alloys

Materials Chemistry and Physics ◽

10.1016/j.matchemphys.2011.11.018 ◽

2012 ◽

Vol 132 (1) ◽

pp. 166-174 ◽

Cited By ~ 39

Author(s):

Y. Huang ◽

F.J. Humphreys

Keyword(s):

Grain Boundary ◽

Grain Growth ◽

Aluminium Alloys ◽

Single Phase ◽

Boundary Mobility ◽

Grain Boundary Mobility

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New Understanding of Abnormal Grain Growth Approached by Solid-State Wetting along Grain Boundary or Triple Junction

Materials Science Forum ◽

10.4028/www.scientific.net/msf.467-470.745 ◽

2004 ◽

Vol 467-470 ◽

pp. 745-750 ◽

Cited By ~ 4

Author(s):

Nong Moon Hwang

Keyword(s):

Solid State ◽

Grain Boundary ◽

Grain Growth ◽

Triple Junction ◽

Boundary Energy ◽

Growth Front ◽

Abnormal Grain Growth ◽

Boundary Mobility ◽

Grain Boundary Mobility ◽

Mc Simulation

Although it has been generally believed that the advantage of the grain boundary mobility induces abnormal grain growth (AGG), it is suggested that the advantage of the low grain boundary energy, which favors the growth by solid-state wetting, induces AGG. Analyses based on Monte Carlo (MC) simulation show that the approach by solid-state wetting could explain AGG much better than that by grain boundary mobility. AGG by solid-state wetting is supported not only by MC simulations but also by the experimental observation of microstructure evolution near or at the growth front of abnormally growing grain. The microstructure shows island grains and solid-state wetting along grain boundary and triple junction.

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Influence of Grain Boundary Mobility on Microstructure Evolution during Recrystallisation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.715-716.191 ◽

2012 ◽

Vol 715-716 ◽

pp. 191-196

Author(s):

Myrjam Winning ◽

Dierk Raabe

Keyword(s):

Grain Boundary ◽

Cellular Automaton ◽

Grain Boundaries ◽

Single Crystals ◽

Microstructure Evolution ◽

Texture Evolution ◽

Three Dimensional ◽

Boundary Mobility ◽

Metallic Materials ◽

Grain Boundary Mobility

The paper introduces first investigations on how low angle grain boundaries can influence the recrystallisation behaviour of crystalline metallic materials. For this purpose a three-dimensional cellular automaton model was used. The approach in this study is to allow even low angle grain boundaries to move during recrystallisation. The effect of this non-zero mobility of low angle grain boundaries will be analysed for the recrystallisation of deformed Al single crystals with Cube orientation. It will be shown that low angle grain boundaries indeed influence the kinetics as well as the texture evolution of metallic materials during recrystallisation.

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Secondary Recrystallization Goss Texture Development in a Binary Fe81Ga19 Sheet Induced by Inherent Grain Boundary Mobility

Metals ◽

10.3390/met9121254 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1254

Author(s):

Zhenghua He ◽

Yuhui Sha ◽

Ning Shan ◽

Yongkuang Gao ◽

Fan Lei ◽

...

Keyword(s):

Grain Boundary ◽

Grain Boundaries ◽

Grain Growth ◽

Misorientation Angle ◽

Secondary Recrystallization ◽

Angle Distribution ◽

Boundary Mobility ◽

Goss Texture ◽

Grain Boundary Mobility ◽

Misorientation Angle Distribution

Secondary recrystallization Goss texture was efficiently achieved in rolled, binary Fe81Ga19 alloy sheets without the traditional dependence on inhibitors and the surface energy effect. The development of abnormal grain growth (AGG) of Goss grains was analyzed by quasi-situ electron backscatter diffraction (EBSD). The special primary recrystallization texture with strong {112}–{111}<110> and weak Goss texture provides the inherent pinning effect for normal grain growth by a large number of low angle grain boundaries (<15°) and very high angle grain boundaries (>45°) according to the calculation of misorientation angle distribution. The evolution of grain orientation and grain boundary characteristic indicates that the higher fraction of high energy grain boundaries (20–45°) around primary Goss grains supplies a relative advantage in grain boundary mobility from 950 °C to 1000 °C. The secondary recrystallization in binary Fe81Ga19 alloy is realized in terms of the controllable grain boundary mobility difference between Goss and matrix grains, coupled with the orientation and misorientation angle distribution of adjacent matrix grains.

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