Effect of grain boundary faceting on kinetics of grain growth and microstructure evolution

2005 ◽  
Vol 40 (4) ◽  
pp. 875-879 ◽  
Author(s):  
Eugen Rabkin
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Microstructure Evolution ◽  
Kinetics Of

Grain Boundary Engineering by Application of Mechanical Stresses

2007 ◽  
Vol 558-559 ◽  
pp. 987-992
Author(s):  
Myrjam Winning
Keyword(s):  
Stress Field ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Mechanical Stress ◽  
Grain Growth ◽  
Microstructure Evolution ◽  
Mechanical Stresses ◽  
Grain Boundary Engineering ◽  
New Approach ◽  
Kinetics Of

It is shown that an externally applied mechanical stress field can change the kinetics of individual grain boundaries. Moreover, such mechanical stresses also have influence on grain growth and recrystallization kinetics and can strongly affect the microstructure evolution, so that the application of mechanical stresses during annealing can be used as a new approach in the field of grain boundary engineering.

Diffusion Mechanisms in Nanocrystalline and Nanolaminated Au-Cu

2007 ◽  
Vol 266 ◽  
pp. 13-28 ◽  
Author(s):  
Alan F. Jankowski
Keyword(s):  
Low Temperature ◽  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Diffusion ◽  
Bulk Diffusion ◽  
Grain Boundary Diffusion ◽  
Dominant Mechanism ◽  
Temperature Range ◽  
Diffusion Mechanisms ◽  
Kinetics Of

Thermal anneal treatments are used to identify the temperature range of the two dominant diffusion mechanisms – bulk and grain boundary. To assess the transition between mechanisms, the low temperature range for bulk diffusion is established utilizing the decay of static concentration waves in composition-modulated nanolaminates. These multilayered structures are synthesized using vapor deposition methods as thermal evaporation and magnetron sputtering. However, at low temperature the kinetics of grain-boundary diffusion are much faster than bulk diffusion. The synthesis of Au-Cu alloys (0-20 wt.% Cu) with grain sizes as small as 5 nm is accomplished using pulsed electro-deposition. Since the nanocrystalline grain structure is thermally unstable, these structures are ideal for measuring the kinetics of grain boundary diffusion as measured by coarsening of grain size with low temperature anneal treatments. A transition in the dominant mechanism for grain growth from grain boundary to bulk diffusion is found with an increase in temperature. The activation energy for bulk diffusion is found to be 1.8 eV·atom-1 whereas that for grain growth at low temperatures is only 0.2 eV·atom-1. The temperature for transitioning from the dominant mechanism of grain boundary to bulk diffusion is found to be 57% of the alloy melt temperature and is dependent on composition.

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.

scholarly journals Influence of Finite Mobilities of Triple Junctions on the Grain Morphology and Kinetics of Grain Growth

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 185
Author(s):  
Ernst Gamsjäger ◽  
Boris Gschöpf ◽  
Jiří Svoboda
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Triple Junction ◽  
Cell Model ◽  
Grain Morphology ◽  
Triple Junctions ◽  
Grain Sizes ◽  
Heat Treated ◽  
Niobium Microalloyed Steel ◽  
Kinetics Of

Grain boundary networks composed of equal microstructural elements were investigated in a recent paper. In this work a more complicated artificial grain topology consisting of one four-sided, two six-sided and one eight-sided grain is designed to further investigate the influence of grain boundary and triple junction mobilities on the kinetics of the system in more detail. Depending on the value of the equal mobility of all triple junctions, the initially square-shaped four-sided grain changes its shape to become more or less rectangular. This indicates that the grain morphology is influenced by the value of the mobility of the triple junctions. It is also demonstrated that a grain arrangement with low mobility triple junctions controlling the kinetics of grain growth enhances growth of the large eight-sided grains. In addition, grain growth is investigated for different values of mobilities of triple junctions and grain boundaries. A strong elongation of several grains is predicted by the modeling results for reduced mobilities of the microstructural grain boundary elements. The two-dimensional modeling results are compared to micrographs of a heat-treated titanium niobium microalloyed steel. This feature, namely the evolution of elongated grains, is observed in the micrograph due to the pinning effect of (Ti, Nb)C precipitates at elevated soaking temperatures of around 1100 °C. Furthermore, the experiments show that a broader distribution of the grain sizes occur at 1100 °C compared to soaking temperatures, where pinning due to precipitates plays a less prominent role. A widening of the distribution of the grain sizes for small triple junction mobilities is also predicted by the unit cell model.

Effect of Deformation on the Austenite to Pearlite Transformation

2011 ◽  
Vol 284-286 ◽  
pp. 2358-2365 ◽  
Author(s):  
Shu Lan Zhang
Keyword(s):  
Carbon Steel ◽  
Grain Boundary ◽  
Microstructure Evolution ◽  
Interlamellar Spacing ◽  
Avrami Equation ◽  
Kinetics Of

The microstructure evolution of the supercooling austenite for the eutectoid carbon steel during deformation was analyzed. The experiment results show that during deformation part of the supercooling austenite transformed to pearlite. The pearlite transformation began around the grain boundary. The interlamellar spacing of the pearlite was fine. In addition, the kinetics of the austenite to pearlite transformation during deformation was discussed in detail. The analysis indicates that the kinetics of the pearlite transformation under deformation can be described by the Avrami equation: . Particularly, in the Avrami equation the value b varied obviously with the change of the deformation conditions. However, the influence of the deformation conditions on the value n was little.

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

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.

Grain-growth kinetics in a nanocrystalline 2 yttria-stabilized tetragonal zirconia polycrystals ceramic with a silica-based glassy phase

2003 ◽  
Vol 18 (4) ◽  
pp. 950-955 ◽  
Author(s):  
O. Markhsev ◽  
R. Chaim
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Growth Kinetics ◽  
Boundary Diffusion ◽  
Glassy Phase ◽  
Tetragonal Zirconia ◽  
Two Phase ◽  
Grain Growth Kinetics ◽  
Kinetics Of ◽  
Grain Coalescence

Grain-growth kinetics of a nanocrystalline 2 yttria-stabilized tetragonal zirconia polycrystals ceramic containing a silica-based glassy phase was determined at 1200 to 1600 °C. At short durations below 1300 °C, the slow grain growth was associated with zirconia dissolution for composition equilibration. The significant increase in the grain size started only after 10 h at 1400 °C or at shorter durations at higher temperatures. Clusters of the cubic grains formed at the two-phase field confirm the inhibited tetragonal grain growth to be independent of the cubic grains. The microstructure evolution during the tetragonal grain growth was interpreted in terms of grain coalescence. Grain growth was initiated by contact flattening and followed by grain-boundary diffusion through the grain-boundary glassy phase. Some aspects of cation diffusion within the viscous glass were also discussed.

Role of inclination dependence of grain boundary energy on the microstructure evolution during grain growth

2020 ◽  
Vol 188 ◽  
pp. 641-651 ◽  
Author(s):  
Hesham Salama ◽  
Julia Kundin ◽  
Oleg Shchyglo ◽  
Volker Mohles ◽  
Katharina Marquardt ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Microstructure Evolution ◽  
Boundary Energy ◽  
Grain Boundary Energy

scholarly journals Kinetics of Grain Boundary Networks Controlled by Triple Junction and Grain Boundary Mobility

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 977 ◽  
Author(s):  
Ernst Gamsjäger ◽  
Daniel Ogris ◽  
Jiří Svoboda
Keyword(s):  
Analytical Solution ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Triple Junction ◽  
Irreversible Thermodynamics ◽  
Force Balance ◽  
Structural Elements ◽  
Grain Boundary Mobility ◽  
Kinetics Of

The kinetics of a triple junction of grain boundaries with distinct specific energies and mobilities and a finite mobility of the triple junction is investigated. The microstructure is approximated by different 2D settings consisting of typical structural elements. First, the migration of the triple point together with the adjacent grain boundaries, is simulated, assuming that the grains are infinitely large. Secondly, growth or shrinkage of finite n-sided grains is simulated by altering the boundary conditions and the results are compared to the already published analytical solution. The numerical results coincide with the corrected analytical solution. This solution can be derived either by applying the principle of maximum dissipation, or by applying the force balance at the triple junction within the framework of linear irreversible thermodynamics. The change of the area of infinite and finite grains is investigated analytically and numerically. By comparing the results of both approaches, the influence of the initial topology of the structural elements on the kinetics of grain growth can be estimated. Furthermore, the kinetics of grain growth of different idealized grain boundary networks is investigated. It is shown that square shaped grains surrounded by hexagons and dodecagons result in a more realistic grain growth scenarios than squares surrounded by octagons. A deviation from idealized grain boundary arrangements is e.g., observed, due to different triple junction mobilities, and the initially n-sided regular grain deforms in a complex manner.

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