Phase-field study of dynamic velocity variations during directional solidification of eutectic NiAl-34Cr

Kellner, Michael; Kunz, Willfried; Steinmetz, Philipp; Hötzer, Johannes; Nestler, Britta

doi:10.1016/j.commatsci.2017.12.053

Cited by 17 publications

(15 citation statements)

References 33 publications

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“…The used phase-field model is based on the grand potential functional [23,24]. A detailed description of its implementation is given in the literature [17,25,26], and further examples for its application to the directional solidification of eutectic systems are reported in [17,19,20,[27][28][29][30]. The local phase fractions of the phases are represented by the N order parameters /â, which are stored in the vector /.…”

Section: Phase-field Modelmentioning

confidence: 99%

“…The local phase fractions of the phases are represented by the N order parameters /â, which are stored in the vector /. Similar to the works [20,31,32], the phases a; b; . .…”

Section: Phase-field Modelmentioning

confidence: 99%

“…The advantages of the parabolically approximated functions are their lightweight computations and the proper representation of the thermodynamic information. In recent years, different binary [3,5,[14][15][16] and ternary [5,[17][18][19][20][21] alloys have therefore been modeled with parabolically approximated functions. A further advantage of this approach is that these functions are suitable for the application in free-energy-based [8,22] as well as in grand-potential-based phase-field models [23,24].…”

Section: Introductionmentioning

confidence: 99%

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Data workflow to incorporate thermodynamic energies from Calphad databases into grand-potential-based phase-field models

et al. 2021

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In order to approximate Gibbs energy functions, a semi-automated framework is introduced for binary and ternary material systems, using Calphad databases. To generate Gibbs energy formulations by means of second-order polynomials, the framework includes a precise approach. Furthermore, an optional extensional step enables the modeling of systems in which a direct generation leads to the unsatisfactory results in the representation of the thermodynamics. Furthermore, an optional extensional step enables the modeling of systems, in which a direct generation leads to the unsatisfactory results, when representing the thermodynamics. Within this extension, the commonly generated functions are modified to satisfy the equilibrium conditions in the observed material systems, leading to a better correlation with thermodynamic databases. The generated Gibbs energy formulations are verified by recalculating the equilibrium concentrations of the phases and rebuilding the phase diagrams in the considered concentration and temperature ranges, prior to the simulation studies. For all comparisons, a close match is achieved between the results and the Calphad databases. As practical examples of the method, phase-field simulation studies for the directional solidification of the binary – and the ternary – eutectic systems are performed. Good agreements between the simulation results and the reported theoretical and experimental studies from literature are found, which indicates the applicability of the presented approaches. Graphical Abstract

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Section: Phase-field Modelmentioning

confidence: 99%

“…The local phase fractions of the phases are represented by the N order parameters /â, which are stored in the vector /. Similar to the works [20,31,32], the phases a; b; . .…”

Section: Phase-field Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Data workflow to incorporate thermodynamic energies from Calphad databases into grand-potential-based phase-field models

et al. 2021

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“…The influence of changing solidification velocities on the adjustment processes of the fibers into a hexagonal arrangement is investigated in [38]. Depending on the process conditions and the melt composition, differently strong amounts of impurity-driven Mullins-Sekerka instabilities can be observed, which can result in the formation of eutectic colonies.…”

Section: Raj and Loccimentioning

confidence: 99%

Phase-field study of eutectic colony formation in NiAl-34Cr

et al. 2020

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The formation of two-phase eutectic colonies is often observed in microstructures of directionally solidified ternary alloys. Their formation is driven by microscopic instabilities in a macroscopic planar solidification front, due to impurities of the minor component, diffusing from the two solidifying phases into the liquid. The growth conditions for eutectic colonies, their interactions and their responses to the microstructure during growth are the focus of the current work. Therefore, phase-field simulations based on a grand potential formalism are performed for the high-performance material NiAl-34Cr. To enable the evolution of eutectic colonies in two-dimensional simulations, a concentrationdriven nucleation mechanism is introduced into a multiphase-field framework and is subsequently validated. With this mechanism, two-dimensional largescale phase-field simulations are conducted to study the influence of the applied temperature gradient on the evolving colonies. The patterns are quantitatively analyzed by measuring their number, size and height. Furthermore, the adjustment processes between the eutectic colonies during the directional solidification are investigated. The results demonstrate the ability of the presented phase-field approach with integrated nucleation mechanism for the formation of eutectic colonies in two-dimensional simulations.

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“…Accordingly, due to the significant effect of the solidification velocity on the pattern formation [ 23 , 24 , 25 , 26 ], the existence of multiple velocities within a single experiment allows studying the interaction of neighboring lamellae with different growth velocities. This can give a better insight into the ongoing velocity-controlled mechanisms in the solidification process and is considered as one of the main advantages of the RDS technique to the DS process.…”

Section: Introductionmentioning

confidence: 99%

Rotating Directional Solidification of Ternary Eutectic Microstructures in Bi-In-Sn: A Phase-Field Study

2022

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For the first time, the experimental processing condition of a rotating directional solidification is simulated in this work, by means of a grand-potential-based phase-field model. To simulate the rotating directional solidification, a new simulation setup with a rotating temperature field is introduced. The newly developed configuration can be beneficent for a more precise study of the ongoing adjustment mechanisms during temperature gradient controlled solidification processes. Ad hoc, the solidification of the ternary eutectic system Bi-In-Sn with three distinct solid phases α,β,δ is studied in this paper. For this system, accurate in situ observations of both directional and rotating directional solidification experiments exist, which makes the system favorable for the investigation. The two-dimensional simulation studies are performed for both solidification processes, considering the reported 2D patterns in the steady state growth of the bulk samples. The desired αβαδ phase ordering repeat unit is obtained within both simulation types. By considering anisotropy of the interfacial energies, experimentally reported tilted lamellae with respect to normal vectors of the solidification front, as well as predominant role of αβ anisotropy in tilting phenomenon, are observed. The results are validated by using the Jackson–Hunt analysis and by comparing with the existing experimental data. The convincing agreements indicate the applicability of the introduced method.

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Phase-field study of dynamic velocity variations during directional solidification of eutectic NiAl-34Cr

Cited by 17 publications

References 33 publications

Data workflow to incorporate thermodynamic energies from Calphad databases into grand-potential-based phase-field models

Data workflow to incorporate thermodynamic energies from Calphad databases into grand-potential-based phase-field models

Phase-field study of eutectic colony formation in NiAl-34Cr

Rotating Directional Solidification of Ternary Eutectic Microstructures in Bi-In-Sn: A Phase-Field Study

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