The effect of elastic misfit strain on the morphological evolution of γ’-precipitates in a model Ni-base superalloy

Yoo, Yong Shim; Yoon, Duk Yong; Henry, Michael F.

doi:10.1007/bf03055324

Cited by 64 publications

(10 citation statements)

References 44 publications

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“…Then, the divergence of solute atom supply at the corners enhances their growth which results in a concave morphology. It is also shown that, in high precipitate density, the precipitates have a cuboidal shape and, in low precipitate density, they grow dendritically, which has been reported in previous studies of nickel-based superalloys [11].…”

Section: Introductionsupporting

confidence: 79%

“…These effects can be well understood by observing the effect of the precipitate density on the growth pattern of the precipitate. The effects of particle density and supersaturation on particle morphology were reported in the SEM work by Yoo et al [11]. There it was revealed that, for high precipitate density, the precipitate grows as a square shape; in intermediate density, a concave shape appears; and in low density the precipitate shows dendritic growth.…”

Section: Numerical Simulationmentioning

confidence: 84%

“…Competition of these factors produces various morphological structures during the time evolution of the precipitates. These include cubic, rectangular, cuboidal and dendritic structures and, particularly, can bring about inverse coarsening, such as particle splitting phenomenon [3][4][5][6][7][8][9][10][11]. Figure 1 shows various morphologies of γ particles coherently grown from the γ phase in a nickel-base superalloy system, under different aging conditions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A phase field model for phase transformation in an elastically stressed binary alloy

Yeon¹,

Cha²,

Kim³

et al. 2005

Modelling Simul. Mater. Sci. Eng.

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We introduce a phase field model which permits the study of the morphological evolution of second phase particles coherently precipitated from the mother phase in elastically stressed alloys. The model has three field variables: the concentration of solute atoms, the displacement field, and the phase field. These fields are coupled via interaction terms in the free energy functional and through kinetic factors. In the model, the interfacial region is defined as a mixture of the mother and second phases, which have the same chemical potential but different compositions. A matched asymptotic expansion analysis of the model is carried out. In the sharp interface limit, our model produces the modified Gibbs-Thomson equation at the coherent interface, which includes not only the effect of interface curvature but also that of coherent elastic strain energy. Twodimensional computations are performed for the microstructural evolution, and precipitate growth in the elastically anisotropic media. Our results are consistent with previous experimental and theoretical studies.

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Section: Introductionsupporting

confidence: 79%

Section: Numerical Simulationmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A phase field model for phase transformation in an elastically stressed binary alloy

Yeon¹,

Cha²,

Kim³

et al. 2005

Modelling Simul. Mater. Sci. Eng.

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“…At 700 K, the Cr concentration increases with time and then splits into two peaks, as shown in Figure 8 a–d. It can be seen from the experiment that the particle splitting requires specific conditions [ 21 ], and that the phenomenon of particle splitting was also found during the growth and coarsening of γ′ precipitates in Ni-based superalloys [ 48 , 49 ], which is caused by the mismatch of the interface energy and the elastic energy. The particle splits into smaller ones to relax the elastic energy when its size reaches a critical value [ 48 ].…”

Section: Resultsmentioning

confidence: 99%

Elastic Strain Relaxation of Phase Boundary of α′ Nanoscale Phase Mediated via the Point Defects Loop under Normal Strain

et al. 2023

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Irradiation-induced point defects and applied stress affect the concentration distribution and morphology evolution of the nanophase in Fe–Cr based alloys; the aggregation of point defects and the nanoscale precipitates can intensify the hardness and embrittlement of the alloy. The influence of normal strain on the coevolution of point defects and the Cr-enriched α′ nanophase are studied in Fe-35 at.% Cr alloy by utilizing the multi-phase-field simulation. The clustering of point defects and the splitting of nanoscale particles are clearly presented under normal strain. The defects loop formed at the α/α′ phase interface relaxes the coherent strain between the α/α′ phases, reducing the elongation of the Cr-enriched α′ phase under the normal strains. Furthermore, the point defects enhance the concentration clustering of the α′ phase, and this is more obvious under the compressive strain at high temperature. The larger normal strain can induce the splitting of an α′ nanoparticle with the nonequilibrium concentration in the early precipitation stage. The clustering and migration of point defects provide the diffusion channels of Cr atoms to accelerate the phase separation. The interaction of point defect with the solution atom clusters under normal strain provides an atomic scale view on the microstructure evolution under external stress.

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“…The secondary arms tending to <00

> can be observed in Figure 6 d; its formation and evolution are closely related to the interfacial stability. Yoo et al [ 19 , 46 ] showed that the dependence of morphological instability on supersaturation remains valid if sufficient supersaturation is present in the matrix. According to the analysis of Mullins and Sekerka [ 10 ], the critical instability radius R c of precipitate can be described by Equation (4):

where l is the number of protrusions, R* is the critical radius of the nucleation, Γ D is the capillary constant, and S is the relative supersaturation.…”

Section: Discussionmentioning

confidence: 99%

The Mechanism of Dendrite Formation in a Solid-State Transformation of High Aluminum Fe-Al Alloys

Yang

Zhang

et al. 2023

Materials

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The mechanism of solid-state dendrite formation in high-aluminum Fe-Al alloys is not clear. Applying an in-situ observation technique, the real-time formation and growth of FeAl solid-state dendrites during the eutectoid decomposition of the high-temperature phase Fe5Al8 is visualized. In-situ experiments by HT-CSLM reveal that proeutectoid FeAl usually does not preferentially nucleate at grain boundaries regardless of rapid or slow cooling conditions. The critical radii for generating morphological instability are 1.2 μm and 0.9 μm for slow and rapid cooling, respectively. The morphology after both slow and rapid cooling exhibits dendrites, while there are differences in the size and critical instability radius Rc, which are attributed to the different supersaturation S and the number of protrusions l. The combination of crystallographic and thermodynamic analysis indicates that solid-state dendrites only exist on the hypoeutectoid side in high-aluminum Fe-Al alloys. A large number of lattice defects in the parent phase provides an additional driving force for nucleation, leading to coherent nucleation from the interior of the parent phase grains based on the orientation relationship {3¯30}Fe5Al8//{1¯10}FeAl, <111¯>Fe5Al8//<111¯>FeAl. The maximum release of misfit strain energy leads to the preferential growth of the primary arm of the nucleus along <111¯> {1¯10}. During the rapid cooling process, a large supersaturation is induced in the matrix, driving the Al atoms to undergo unstable uphill diffusion and causing variations in the concentration gradient as well as generating constitutional undercooling, ultimately leading to morphological instability and the growth of secondary arms.

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The effect of elastic misfit strain on the morphological evolution of γ’-precipitates in a model Ni-base superalloy

Cited by 64 publications

References 44 publications

A phase field model for phase transformation in an elastically stressed binary alloy

A phase field model for phase transformation in an elastically stressed binary alloy

Elastic Strain Relaxation of Phase Boundary of α′ Nanoscale Phase Mediated via the Point Defects Loop under Normal Strain

The Mechanism of Dendrite Formation in a Solid-State Transformation of High Aluminum Fe-Al Alloys

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