A mean field model of agglomeration as an extension to existing precipitation models

Seret, Anthony; Moussa, Charbel; Bernacki, Marc; Bozzolo, Nathalie

doi:10.1016/j.actamat.2020.04.029

Cited by 5 publications

(2 citation statements)

References 72 publications

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“…The corresponding simulation predictions were 28 and 16 nm, respectively. Although relatively minor, the differences between measured and predicted sizes may be ascribed to the experimental difficulty in SEM imaging of very fine precipitates (especially for c¢), stereological considerations (i.e., the 3D nature of the simulations versus the 2D measurements on a polished sections), precipitate agglomeration/encounter during the latter stages of aging, [47,48] or other effects neglected in the analysis. The comparison of predictions from the nucleation-and-growth simulations also showed moderate-to-good agreement with precipitation trends inferred from neutron-diffraction lattice-parameter measurements ( Figure 9).…”

Section: Nucleation-and-growth (Nandg) Analysismentioning

confidence: 99%

In-Situ Determination of Precipitation Kinetics During Heat Treatment of Superalloy 718

Cormier

Gadaud

Czaplicki

et al. 2020

Metall Mater Trans A

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Two in-situ test techniques were used to obtain insight into the isothermal precipitation kinetics of c¢¢ and c¢ in superalloy 718. The first method consisted of measurements of Young's modulus using a dynamic-resonance method (DRM), and the other comprised determination of the evolution of the lattice parameter of the c-matrix phase via neutron diffraction. For both techniques, solution-treated-and-water-quenched samples were heated to a nominal test temperature of 923 K, 953 K, 1013 K, or 1053 K and held for a time of~5 to 50 hours, at the end of which a near-steady condition in terms of an apparently-constant modulus/lattice parameter had been achieved. The observations from each test technique suggested sequential periods of rapid initial increase in volume fraction followed by a gradually-decreasing rate of change. The data were converted to transformed fraction as a function of time and interpreted in terms of phenomenological (JMAK) and mechanistic (nucleation-and-growth) models. From the former approach, Avrami exponents which decreased from approximately unity at the lower two temperatures to~0.5 at the highest temperature, were deduced. The transformed fraction-versus-time behaviors were well replicated using fast-acting numerical simulations based on the mechanistic model. These simulations highlighted the competition between nucleation and growth in determining overall transformation kinetics.

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Section: Nucleation-and-growth (Nandg) Analysismentioning

confidence: 99%

In-Situ Determination of Precipitation Kinetics During Heat Treatment of Superalloy 718

Cormier

Gadaud

Czaplicki

et al. 2020

Metall Mater Trans A

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show abstract

“…A second related consequence is that the diffusion fields in the matrix surrounding growing or shrinking precipitates may overlap, which increases the kinetics of solute transport between precipitates in the coarsening stage. The extreme case is when precipitates can touch each other, which may lead to coagulation [113], and whose effect on the kinetics of microstructure evolution has been modelled in Ni superalloys [119]. These correlation effects are most pronounced during the coarsening stage.…”

Section: Effects Of Finite Volume Fractionmentioning

confidence: 99%