Modeling the final sintering stage of doped ceramics: mutual interaction between grain growth and densification

Gong, Mingming; Castro, Ricardo H. R.; Liu, F.

doi:10.1007/s10853-017-1617-1

Cited by 11 publications

(16 citation statements)

References 65 publications

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“…Since both NC metals and NC ceramics contain the high‐density GBs, several theories describing the stabilization mechanism in metals exerted by, for example, the GB segregation, the solute drag, the intrinsic drag, etc., can be used to account for the enhanced thermal stability in ceramics 43,62,95 . Despite of this, it should be noted that compared to metals, the ceramics are often not fully dense and contain the pores.…”

Section: Thermo‐kinetic Description Of Grain Growth Processmentioning

confidence: 99%

“…Although the derivation of Equation () based on the well‐formulated segregation‐dependent thermodynamic and kinetic parameters couples both the grain growth and the densification, the two processes are previously modeled separately and the mutual interaction between them is ignored. Consequently, one may underestimate the driving force for grain growth but overestimate that for densification 62 . In other words, the actual driving forces for describing effects of doping may be not accurate.…”

Section: Thermo‐kinetic Description Of Grain Growth Processmentioning

confidence: 99%

“…Besides, since the framework of Equation () originates from the ideal grain growth equation (ie, Equation ) that fundamentally treats a GB migration process, the expression of Equation () omits the effect of surface energy of pores, although this parameter actually acts on the grain growth behavior of NC ceramics 65 . In order to solve the two problems, applying the thermodynamic extremal principle, Gong et al 62 developed a new model for grain growth and densification in the final stage of sintering of doped ceramics, with segregation‐dependent interfacial energies and mobilities (or diffusivities), that is,

\frac{d D}{d t} = \frac{false[γ + λ (ρ) γ^{s} false] M false(x^{GB}, x^{b}, x^{s}, x_{0} false)}{D} .

where λ ( ρ ) is a ρ ‐dependent parameter, γ s is the surface energy, M ( x GB , x b , x s , and x 0 ) is the solute concentration‐dependent GB mobility. Obviously, the grain growth and the densification are treated together and the interaction between them is reflected.…”

Section: Thermo‐kinetic Description Of Grain Growth Processmentioning

confidence: 99%

“…Another example is the final stage of sintering (at 1623 K) of Al 2 O 3 doped with 1000 ppm Y 2 O 3 or La 2 O 3 62 . By recording the grain size as a function of relative density during the isothermal process, it was found that the addition of La 2 O 3 lead to a smaller grain size (namely a higher thermal stability) at the same relative density compared to that of Y 2 O 3 , as shown in Figure 9.…”

Section: Thermo‐kinetic Description Of Grain Growth Processmentioning

confidence: 99%

“…Applying the model (Equation ) to fit the experiment data, the good agreement between them is observed (refer to Figure 9), from which, the segregation enthalpy and the dopant‐cation GB diffusion coefficient (in the case of dilute solution limit) are fitted as about − 56.3 and − 60.8 kJ/mol; and 0.102

D_{0}^{GB}

and 0.078

D_{0}^{GB}

for yttria and lanthana, respectively. Obviously, as compared to the Y 3+ , the La 3+ has a more negative segregation enthalpy and simultaneously a slower GB diffusion coefficient, which thus should be responsible for the higher thermal stability for Al 2 O 3 doped with La 2 O 3 62 …”

Section: Thermo‐kinetic Description Of Grain Growth Processmentioning

confidence: 99%

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Review of thermo‐kinetic correlation during grain growth in nanocrystalline materials

Peng

Jian

Liu

2020

Int J Ceramic Engine & Sci

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Nanocrystalline (NC) materials exhibit many unique properties over their coarse‐grained counterparts due to the high grain boundary density and the small grain size, but they are too difficult to be used in engineering environment because of the poor thermal stability. With regard of this, two strategies are previously proposed to enhance the thermal stability (or impede the grain growth) of NC materials, that is, the thermodynamic and the kinetic approaches. Recent investigations increasingly support that the two approaches may be physically interacted and acted on each other, and they can be treated together within a unified thermo‐kinetic framework. This paper reviews the progress in the investigation of thermo‐kinetic correlation during grain growth in NC materials. First, the theoretical models to describe the concept of the thermo‐kinetic correlation and the grain growth equations developed based on the thermo‐kinetic correlation are reviewed. Second, experimental and simulated evidences to support the coexistence of thermodynamic and kinetic effects are summarized. Third, the potential application of thermo‐kinetic correlation is analyzed and discussed. This paper shows that the stabilization of NC materials can be tailored by the selection of the suitable strategies. Finally, several directions that require further exploration are identified.

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Section: Thermo‐kinetic Description Of Grain Growth Processmentioning

confidence: 99%

Section: Thermo‐kinetic Description Of Grain Growth Processmentioning

confidence: 99%