Grain Growth Kinetics of Cobalt-Doped SnO2 by Varying Nb2O5 Content

2007 ◽  
Vol 534-536 ◽  
pp. 529-532 ◽  
Author(s):  
Dong Gyu Chang ◽  
Joon Hyung Lee ◽  
Jeong Joo Kim
Keyword(s):  
Grain Growth ◽  
Boundary Segregation ◽  
Growth Behavior ◽  
Grain Boundary Segregation ◽  
Growth Exponent ◽  
Space Charges ◽  
Grain Growth Kinetics ◽  
Grain Growth Behavior ◽  
Kinetics Of ◽  
Co Doped

SnO2 ceramics were co-doped with the aliovalent ions of CoO and Nb2O5 and the grain growth behavior of the SnO2 was investigated. When only CoO was doped, the grain growth exponent of SnO2 was 3. As the amount of Nb2O5 increased, the exponent changed from 3 to 2 when 0.505 mol% of Nb2O5 was added. The further addition of Nb2O5 changed the exponent from 2 to 3. When Nb2O5 content was 0.505 mol%, of which the grain growth exponent was 2, it is believed that an iso-electric point is formed without grain boundary segregation, since the respective space charges, generated by Nb5+ and Co3+ might compensate each other.

Grain Boundary Segregation-Induced Phase Transformation and Grain Growth in Y2O3-Stabilized ZrO2 Polycrystals

2014 ◽  
Vol 616 ◽  
pp. 8-13
Author(s):  
Koji Matsui ◽  
Hidehiro Yoshida ◽  
Yuichi Ikuhara
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Boundary Segregation ◽  
Growth Behavior ◽  
Grain Boundary Segregation ◽  
Transmission Electron ◽  
Grain Growth Behavior

We systematically investigated the phase transformation and grain-growth behaviors during sintering in 2 and 3 mol% Y2O3-stabilized tetragonal ZrO2 (2Y and 3Y) and 8 mol% Y2O3-stabilized cubic ZrO2 polycrystals (8Y). In particular, grain-boundary segregation and grain-interior distribution of Y3+ ions were examined by high-resolution transmission electron microscopy (HRTEM)- and scanning transmission electron microscopy (STEM)-nanoprobe X-ray energy dispersive spectroscopy (EDS) techniques. Above 1200°C, grain growth during sintering in 8Y was much faster than that in 2Y and 3Y. In the grain boundaries in these specimens, amorphous layers did not present; however, Y3+ ions segregated at the grain boundaries over a width of about 10 nm. The amount of segregated Y3+ ions in 8Y was significantly less than in 2Y and 3Y. This indicates that the amount of segregated Y3+ ions is related to grain growth behavior; i.e., an increase in segregated Y3+ ions retards grain growth. Therefore, grain-growth behavior during sintering can be reasonably explained by the solute-drag mechanism of Y3+ ions segregating along the grain boundary. In 2Y and 3Y, the cubic-phase regions were formed in grain interiors adjacent to the grain boundaries and/or the multiple junctions in which Y3+ ions segregated, which can be explained by a grain boundary segregation-induced phase transformation (GBSIPT) mechanism.

β Grain Growth Kinetics of a New Metastable β Titanium Alloy

2013 ◽  
Vol 747-748 ◽  
pp. 844-849 ◽  
Author(s):  
Yue Fei ◽  
Xin Nan Wang ◽  
Zhi Shou Zhu ◽  
Jun Li ◽  
Guo Qiang Shang ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Grain Growth ◽  
Kinetic Equations ◽  
Type Equation ◽  
Growth Exponent ◽  
Solution Treated ◽  
Growth Activation ◽  
Grain Growth Kinetics ◽  
Kinetics Of ◽  
Strength And Ductility

Ti-Mo-Nb-Cr-Al-Fe-Si alloy is a new metastable β titanium alloy with excellent combination of strength and ductility. The β grain-growth exponent and the activation energies for β grain growth for the investigated alloy at specified temperature were computed by the kinetic equations and the Arrhenius-type equation. The rate of β grain growth decreases with elongating solution treated time and increases with the increasing solution-treated temperature. The β grain-growth exponents, n, are 0.461, 0.464 and 0.469 at 1113, 1133 and 1153K, respectively. The β grain growth activation energy is determined to be 274 KJ/mol.

β Grain Growth Kinetics of Hot-Rolled TB-13 Alloy

2011 ◽  
Vol 689 ◽  
pp. 472-478 ◽  
Author(s):  
Yue Fei ◽  
Bin Tang ◽  
Hui Chang ◽  
Zhi Shou Zhu ◽  
Zhong Bo Zhou ◽  
...  
Keyword(s):  
Activation Energy ◽  
Grain Growth ◽  
Kinetic Equations ◽  
Type Equation ◽  
Growth Exponent ◽  
Fine Grained ◽  
Solution Treated ◽  
Grain Growth Kinetics ◽  
Hot Rolled ◽  
Kinetics Of

A study on the kinetics of β grain growth of a fine-grained, hot-rolled TB-13 alloy was carried out by isochronal and isothermal solution treatments. The grain size of the as-rolled and as-solution-treated samples was determined by metallographic observation using the linear intercept method. The kinetic equations and the Arrhenius-type equation were applied to calculate the β grain growth exponent and the activation energy for β grain growth at special temperatures. The results showed that the β grain growth rate decreased with elongating solution treated time, but increased with increasing solution treated temperature. The β grain growth exponents (n) were 0.394, 0.403 and 0.406 during the solution treated temperatures at 1103K, 1153K and 1203K, respectively. The values of n increased with increasing solution treated temperature and the determined activation energy (Qm) for β grain growth after holding for 0.5h at 1103K-1203K was around 156KJ/mol.

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 Growth Kinetics of 0.65Ca0.61La0.26TiO3-0.35Sm(Mg0.5Ti0.5)O3 Dielectric Ceramic

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3905
Author(s):  
Jin Liu ◽  
Bingliang Liang ◽  
Jianjun Zhang ◽  
Wen He ◽  
Sheng Ouyang ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Prediction Accuracy ◽  
Sintering Temperature ◽  
Solid State Reaction Method ◽  
Dielectric Ceramic ◽  
Nonlinear Regression Method ◽  
Grain Growth Kinetics ◽  
Grain Growth Behavior ◽  
Kinetics Of

The 0.65Ca0.61La0.26TiO3-0.35Sm(Mg0.5Ti0.5)O3[0.65CLT-0.35SMT] ceramic was prepared by the solid-state reaction method. The effects of sintering process on its microstructure and grain growth behavior were investigated. The Hillert model and a simplified Sellars model were established by linear regression, and the Sellars-Anelli model with a time index was established by using a nonlinear regression method. The results show that the grain size gradually increases with the increase of sintering temperature and holding time. Meanwhile, the sintering temperature has a more significant effect on the grain growth. The grain sizes of 0.65CLT-0.35SMT ceramic were predicted by the three models and compared with the experimentally measured grain size. The results indicate that for the 0.65CLT-0.35SMT ceramic, the Hillert model has the lowest prediction accuracy and the Sellars-Anelli model, the highest prediction accuracy. In this work, the Sellars-Anelli model can effectively predict the grain growth process of 0.65CLT-0.35SMT ceramic.

Effects of TaB 2 and TiB 2 on the grain growth behavior and kinetics of HfB 2 ceramics during pressureless sintering

2020 ◽  
Vol 103 (5) ◽  
pp. 3330-3337 ◽  
Author(s):  
Qi‐Qi Zhu ◽  
Zhan Zhang ◽  
Yan Zhang ◽  
Qiu‐Yu Liu ◽  
Bang‐Chao Song ◽  
...  
Keyword(s):  
Grain Growth ◽  
Growth Behavior ◽  
Pressureless Sintering ◽  
Grain Growth Behavior ◽  
Kinetics Of

Grain Growth Kinetics of Accumulative Roll Bonded AZ61 Alloy

2012 ◽  
Vol 585 ◽  
pp. 387-391 ◽  
Author(s):  
H. Shivananda Nayaka ◽  
Gajanan P. Chaudhari ◽  
B.S. Sunder Daniel
Keyword(s):  
Grain Growth ◽  
Growth Kinetics ◽  
Annealing Temperature ◽  
Isothermal Annealing ◽  
Arrhenius Equation ◽  
Growth Exponent ◽  
Az61 Magnesium Alloy ◽  
Ultrafine Grained ◽  
Grain Growth Kinetics ◽  
Kinetics Of

A detailed study was performed on the grain growth kinetics of ultrafine-grained AZ61 magnesium alloy produced by accumulative roll bonding by carrying out isothermal annealing treatments on the roll bonded samples. Annealing treatments were carried out in the temperature range 423 to 573K for 2 to 120 minutes. As the annealing time and temperature increased, the grain size increased. The effect of annealing temperature and time, on the grain growth can be well explained by the kinetic equation and Arrhenius equation. Based on the experimental results of grain growth during annealing treatments, the grain growth exponent and the activation energy for grain growth were determined. The grain growth kinetic parameters were compared with other magnesium alloys processed by various methods.

scholarly journals Asymptotic Behavior in Grain Growth

1994 ◽  
Vol 343 ◽  
Author(s):  
David T. Wu
Keyword(s):  
Distribution Function ◽  
Asymptotic Behavior ◽  
Grain Growth ◽  
Lower Order ◽  
Growth Behavior ◽  
Experimental Results ◽  
Growth Exponent ◽  
Diffusion Term ◽  
Drift Term ◽  
Grain Growth Behavior

ABSTRACTHillert’s model of grain growth consists of a drift term in size space that leads asymptotically to a distribution function and a growth exponent not often observed. Later theories introduce a diffusion term that is either assumed to dominate the drift term or a correction to it. This paper shows that the lower order drift term alone determines asymptotic grain growth behavior. A possible conclusion is that experimental results may need to be reinterpreted.

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