Tip-splitting instability and transition to seaweed growth during alloy solidification in anisotropically preferred growth direction

Chen, Yun; Billia, B.; Li, Dian Zhong; Nguyen-Thi, Henri; Xiao, Naiqi G.; Bogno, Abdoul-Aziz

doi:10.1016/j.actamat.2013.11.069

Cited by 59 publications

(32 citation statements)

References 43 publications

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“…Seaweed, or dense branching morphology, is known as another important class of interface morphologies in solidification78910. Dendrites are patterns with obvious orientational order, whereas seaweed structures are considered as patterns without orientational order.…”

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confidence: 99%

“…Indeed, it is evidenced that noise at the solid-liquid interface is another crucial factor to drive the transition to the seaweed since the noise with sufficient intensity not only results in the emission of the sidebranches but also destroys the stability of the growing tip. By comparing the real-time observation by the X-Ray radiography with the numerical simulations, Chen et al 10. provided direct evidence of the transition from dendritic or cellular to seaweed structures in solidification of Al-Cu alloys.…”

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confidence: 99%

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Degenerate seaweed to tilted dendrite transition and their growth dynamics in directional solidification of non-axially oriented crystals: a phase-field study

Xing

Dong

et al. 2016

Sci Rep

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We report the results of a phase-field study of degenerate seaweed to tilted dendrite transition and their growth dynamics during directional solidification of a binary alloy. Morphological selection maps in the planes of (G, Vp) and (ε4, Vp) show that lower pulling velocity, weaker anisotropic strength and higher thermal gradient can enhance the formation of the degenerate seaweed. The tip undercooling shows oscillations in seaweed growth, but it keeps at a constant value in dendritic growth. The M-S instability on the tips and the surface tension anisotropy of the solid-liquid interface are responsible for the formation of the degenerate seaweed. It is evidenced that the place where the interfacial instability occurs determines the morphological transition. The transient transition from degenerate seaweed to tilted dendrite shows that dendrites are dynamically preferred over seaweed. For the tilted dendritic arrays with a large tilted angle, primary spacing is investigated by comparing predicted results with the classical scaling power law, and the growth direction is found to be less sensitive to the pulling velocity and the primary spacing. Furthermore, the effect of the initial interface wavelength on the morphological transition is investigated to perform the history dependence of morphological selection.

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confidence: 99%

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confidence: 99%

Degenerate seaweed to tilted dendrite transition and their growth dynamics in directional solidification of non-axially oriented crystals: a phase-field study

Xing

Dong

et al. 2016

Sci Rep

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“…Chen et al. [13] also indicated that the pulling rate, or the withdrawal rate of the DS process is a factor which causes nonplanar solidification front. Derby et al [14] analyzed the heat transfer for crystal growth based on the Bridgman method and summarized that the nonplanar interface causes many defects, such as the propagation of the deleterious wall interactions.…”

Section: Introductionmentioning

confidence: 96%

“…Chen et al [13] stated that the nonplanar solidification front leads to the change of the dendrite growth direction. Chen et al.…”

Section: Introductionmentioning

confidence: 99%

A method for flattening the solidification front in directional solidification technology

Lian

Zhang

2015

Journal of Crystal Growth

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“…However, many manufacturing defects of the single crystal blade have not been eliminated, such as freckles 2) , stray grains 3) and high dislocation levels 4) etc. One of the major factors in causing defects is the nonplanar solidi cation front 2,5,6) . Much research has been carried out for attening the solidi cation front.…”

Section: Introductionmentioning

confidence: 99%

Flattening the Solidification Front by Varying the Wall Thickness of the Mould in Directional Solidification Technology

Lian

Zhang

2016

Mater. Trans.

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A non-planar solidi cation front can cause many defects in the directional solidi cation process. The irregular shape of the cross section of the cast leads to a non-uniform heat distribution and hence causes a non-planar solidi cation front. This paper provides a method to decrease the circumferential temperature gradient in the directional solidi cation process by varying the wall thickness of the mould. The relationship between the wall thickness and the control parameter has been determined. An optimization algorithm for obtaining the control parameter and the corresponding wall thickness of mould is presented with three simulation examples provided to verify the superiority of this method. According to the results the circumferential temperature gradients can be reduced by 68.7%, 72.0% and 88.2% respectively. Moreover, the transverse temperature gradients are reduced by 57.3%, 60.8% and 89.3% accordingly. The solidi cation front with a varying thickness mould is thus attened compared with the un-optimized one.

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Tip-splitting instability and transition to seaweed growth during alloy solidification in anisotropically preferred growth direction

Cited by 59 publications

References 43 publications

Degenerate seaweed to tilted dendrite transition and their growth dynamics in directional solidification of non-axially oriented crystals: a phase-field study

Degenerate seaweed to tilted dendrite transition and their growth dynamics in directional solidification of non-axially oriented crystals: a phase-field study

A method for flattening the solidification front in directional solidification technology

Flattening the Solidification Front by Varying the Wall Thickness of the Mould in Directional Solidification Technology

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