Mechanically Deformed Primary Dendritic Structures Observed During the Solidification of Undercooled Melts

Mullis, Andrew M.; Dragnevski, Kalin I.; Mullis, Andrew M.

doi:10.1002/3527603506.ch20

Cited by 2 publications

(6 citation statements)

References 13 publications

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“…The idea of dendrites deforming by mechanical means has been studied by Pilling and Hellawell [7] and by a group in the UK consisting of Mullis, Dragnevski, Cochrane, Battersby and Walker [8][9][10][11]. Much of their research is on the effects of fluid flow on dendrite secondary arms.…”

Section: Introductionmentioning

confidence: 99%

“…Mullis and co-workers [10] also looked at flow effects on primary arms of copper alloys after micrographs showed strong evidence of bending downstream. Primary dendrite arms are long slender cylinder-shaped structures and, whereas secondary arms have tapered roots where they connect to the primary arm, primary arms have uniform geometry.…”

Section: Introductionmentioning

confidence: 99%

“…Mullis and co-workers, again following the analysis of Pilling and Hellawell, modelled the primary arm as a cylinder subjected to cross-flow along the full length. With the known primary arm diameter, the flow velocity, and the length from the tip where bending occurred, they were able to determine the skin stress on the dendrite at the location of bending [10]. Using the deformation mechanism maps of Frost and Ashby, Mullis and co-workers [10] concluded that the calculated skin stress on the dendrite was equal to the yield stress and that mechanical bending was the most probable cause of the observed deformation.…”

Section: Introductionmentioning

confidence: 99%

“…With the known primary arm diameter, the flow velocity, and the length from the tip where bending occurred, they were able to determine the skin stress on the dendrite at the location of bending [10]. Using the deformation mechanism maps of Frost and Ashby, Mullis and co-workers [10] concluded that the calculated skin stress on the dendrite was equal to the yield stress and that mechanical bending was the most probable cause of the observed deformation. They were able to prove that thermosolutal natural convection was not strong enough to cause the magnitude of bending seen in the primary arms [10].…”

Section: Introductionmentioning

confidence: 99%

“…Using the deformation mechanism maps of Frost and Ashby, Mullis and co-workers [10] concluded that the calculated skin stress on the dendrite was equal to the yield stress and that mechanical bending was the most probable cause of the observed deformation. They were able to prove that thermosolutal natural convection was not strong enough to cause the magnitude of bending seen in the primary arms [10].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Internal convective effects on the lifetime of the metastable phase undercooled Fe–Cr–Ni alloys

Hanlon

Matson

Hyers

2006

Philosophical Magazine Letters

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Differences have been observed between the lifetimes of the metastable phases of undercooled samples of Fe-12 wt% Cr-16 wt% Ni alloy which had been subjected to electromagnetic levitation (EML) and electrostatic levitation (ESL). Internal flow is induced within the samples by positioning forces in EML and much weaker Marangoni forces in ESL. The hypothesis being tested is that the flow within EML samples is strong enough to cause the growing metastable dendrites to deflect so that the secondary arms of adjacent dendrites collide, resulting in early nucleation of the stable phase. Simulations using a commercial computational fluid dynamics software package were performed to determine the time required for collision of the secondary arms to occur. There is quantitative agreement between the numerical time to collision and the experimental lifetime of the metastable phase. It has been determined that the induced convective flow in EML samples is strong enough to cause collision and is the most likely cause of the difference between the lifetimes of the metastable phases in ESL and EML samples.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Internal convective effects on the lifetime of the metastable phase undercooled Fe–Cr–Ni alloys

Hanlon

Matson

Hyers

2006

Philosophical Magazine Letters

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Thermo-solutal and kinetic modes of stable dendritic growth with different symmetries of crystalline anisotropy in the presence of convection

Alexandrov

Galenko

Toropova

2018

Phil. Trans. R. Soc. A.

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Motivated by important applications in materials science and geophysics, we consider the steady-state growth of anisotropic needle-like dendrites in undercooled binary mixtures with a forced convective flow. We analyse the stable mode of dendritic evolution in the case of small anisotropies of growth kinetics and surface energy for arbitrary Péclet numbers and -fold symmetry of dendritic crystals. On the basis of solvability and stability theories, we formulate a selection criterion giving a stable combination between dendrite tip diameter and tip velocity. A set of nonlinear equations consisting of the solvability criterion and undercooling balance is solved analytically for the tip velocity and tip diameter of dendrites with-fold symmetry in the absence of convective flow. The case of convective heat and mass transfer mechanisms in a binary mixture occurring as a result of intensive flows in the liquid phase is detailed. A selection criterion that describes such solidification conditions is derived. The theory under consideration comprises previously considered theoretical approaches and results as limiting cases. This article is part of the theme issue 'From atomistic interfaces to dendritic patterns'.This article is part of the theme issue 'From atomistic interfaces to dendritic patterns'.

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Mechanically Deformed Primary Dendritic Structures Observed During the Solidification of Undercooled Melts

Cited by 2 publications

References 13 publications

Internal convective effects on the lifetime of the metastable phase undercooled Fe–Cr–Ni alloys

Internal convective effects on the lifetime of the metastable phase undercooled Fe–Cr–Ni alloys

Thermo-solutal and kinetic modes of stable dendritic growth with different symmetries of crystalline anisotropy in the presence of convection

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