On the Impact of Macroscopic Phase Separation on Solidification Microstructures

Wu, Menghuai; Ludwig, Andreas; Pelzer, Martin; Postl, Ulrich

doi:10.1002/adem.200500098

Cited by 9 publications

(4 citation statements)

References 17 publications

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“…[11] It is worth mentioning that melt convection and grain sedimentation play the most important role in the macrosegregation formation, a common problem in steel ingots. [11,21] …”

Section: Cet With Convection and Grain Movementmentioning

confidence: 98%

Using a Three-Phase Deterministic Model for the Columnar-to-Equiaxed Transition

Ludwig

2007

Metall Mater Trans A

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112

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In order to overcome the limitations of previous columnar-to-equiaxed (CET) models, which neglect melt convection and the movement of free equiaxed grains, this article presents a three-phase deterministic CET model. With appropriated multiphase volume-averaging approaches, it is possible to account for nucleation and growth of equiaxed grains ahead of a growing columnar front, the influence of melt convection, and grain sedimentation, and the occurrence of a CET in a casting of engineering scale. Special modeling assumptions ensure that both CET mechanisms, namely, ''hard'' and ''soft'' blocking, are tackled. It is highly recommended that both mechanisms should be considered, especially in the situation where grain sedimentation and melt convection are present. Although the current model incorporates almost all the physical variables relevant to a CET event, under special condition of a one-dimensional case, the model still reproduces the results of Hunt's classical CET approach.

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“…[11] It is worth mentioning that melt convection and grain sedimentation play the most important role in the macrosegregation formation, a common problem in steel ingots. [11,21] …”

Section: Cet With Convection and Grain Movementmentioning

confidence: 98%

Using a Three-Phase Deterministic Model for the Columnar-to-Equiaxed Transition

Ludwig

2007

Metall Mater Trans A

Self Cite

112

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“…4 Figure 1b shows a schematic illustration of the microstructural evolution of an immiscible liquid particle, where the minor phase droplets rapidly move and assemble toward the center of the particle against the temperature gradient. Since this finding, extensive work has been carried out on the mechanism [5][6][7] of the formation of this egg-type microstructure, the role of interfacial energy, 8 and bulk ingots with a core-type microstructure. 9 Very recently, we performed phase field simulation of the microstructural evolution of immiscible liquid powder, 10 which permits the general treatment of composite powder with a core/shell structure.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Evolution of Alloy Powder for Electronic Materials with Liquid Miscibility Gap

Ohnuma

Saegusa

Takaku

et al. 2008

Journal of Elec Materi

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The microstructure of powders that are applicable for electronic materials were studied for some systems in which there is a liquid miscibility gap. The characteristic morphologies of an egg-like core type and a uniform secondphase dispersion are shown in relation to the phase diagram, where thermodynamic calculations are a powerful tool for alloy design and the prediction of microstructure. Typical examples of microstructural evolution and properties of Pb-free solders and Ag-based micropowders with high electrical conductivity produced by a gas-atomizing method are presented.

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“…Therefore, such exploratory simulations as done by Ni and Beckermann have become crucially important to achieve just a mere basic understanding of this correlation. This globular equiaxed solidification model was later extended by different authors to investigate the formation of globular equiaxed crystals during channel cooling of A356 aluminum alloy (rheo-casting) [102,103], decomposition and macrosegregation during monotectic solidification [104][105][106], the crystal sedimentation induced macrosegregation in steel ingots [92,107,108], and premature solidification phenomenon during mold filling of shape casting [109]. Evaluation efforts were also made by comparing the simulations with laboratory casting experiments [110,111].…”

Section: Application Of Globular Equiaxed Solidification Modelmentioning

confidence: 99%

Volume-Averaged Modeling of Multiphase Flow Phenomena during Alloy Solidification

Ludwig

Kharicha

2019

Metals

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The most recent developments and applications in volume-averaged modeling of solidification processes have been reviewed. Since the last reviews of this topic by Beckermann and co-workers [Applied Mech. Rev. 1993, p. 1; Annual Rev. Heat Transfer 1995, p. 115], major progress in this area has included i) the development of a mixed columnar-equiaxed solidification model; ii) further consideration of moving crystals and crystal dendritic morphology; and iii) the model applications to analyze the formation mechanisms of macrosegregation, as-cast structure, shrinkage cavity and porosity in different casting processes. The capacity of computer hardware is still a limiting factor. However, many calculation examples, as verified by the laboratory casting experiments, or even by the casting processes at a small industrial scale, show great application potential. Following the trend of developments in computer hardware (projection according to Moore’s law), a full 3D calculation of casting at the industry scale with the multiphase volume-averaged solidification models will become practically feasible in the foreseeable future.

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On the Impact of Macroscopic Phase Separation on Solidification Microstructures

Abstract: By using the term ªphase separationº we have a spatial separation due to the relative movement between different liquid and solid phases in mind. This relative movement might Wu et al./On the Impact of Macroscopic Phase Separation on Solidification Microstructures COMMUNICATIONS 846

Cited by 9 publications

References 17 publications

Using a Three-Phase Deterministic Model for the Columnar-to-Equiaxed Transition

Using a Three-Phase Deterministic Model for the Columnar-to-Equiaxed Transition

Microstructural Evolution of Alloy Powder for Electronic Materials with Liquid Miscibility Gap

Volume-Averaged Modeling of Multiphase Flow Phenomena during Alloy Solidification

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