Constitutional supercooling principle during dendritic growth

Conference · · TMS (The Metallurgical Society) Paper Selection; (USA)

OSTI ID:5451355

Laxmanan, V ^[1]

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1. Case Western Reserve Univ., Cleveland, OH (USA)

The stability of a planar solid-liquid interface at low growth rates is usually explained in terms of the constitutional supercooling criterion. For a given thermal gradient in the liquid, the planar interface breaks down to form cells if the growth rate exceeds a certain value R{sub p}. The liquid in contact with the planar interface at this critical condition is constitutionally supercooled. At higher growth rates, the cells themselves become unstable and a dendritic structure develops. A satisfactory theory for dendritic growth (in an alloy) should, therefore, be able to demonstrate that liquid in contact with a dendrite tip should be constitutionally supercooled. However, at extremely large growth rates, morphological stability theories indicate that a planar interface can remain stable provided the growth rate exceeds a certain value, R{sub a}. Thus, at these large growth rates, constitutional supercooling should again vanish. A theory for dendritic growth in a binary alloy is presented here which satisfactorily explains these transitions.

• OSTI ID: 5451355
• Report Number(s): CONF-840909--
• Conference Information: Journal Name: TMS (The Metallurgical Society) Paper Selection; (USA) Journal Volume: 56
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOY SYSTEMS
BINARY ALLOY SYSTEMS
COOLING
CRYSTAL GROWTH METHODS
DENDRITIC WEB GROWTH METHOD
FLUIDS
INTERFACES
LIQUIDS
MATHEMATICAL MODELS
MORPHOLOGY
PHASE TRANSFORMATIONS
SOLIDIFICATION
STABILITY
TEMPERATURE GRADIENTS