Modeling of combined melt convection and solid transport during equiaxed dendritic solidification

Book · Sat Dec 30 23:00:00 EST 1995

OSTI ID:227781

Wang, C Y ^[1]; Beckermann, C ^[2]

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1. Univ. of Hawaii, Honolulu, HI (United States). Dept. of Mechanical Engineering
2. Univ. of Iowa, Iowa City, IA (United States). Dept. of Mechanical Engineering

The effects of thermosolutal melt convection and the transport of solid, in the form of free equiaxed crystals, on the formation of grain structure and macrosegregation in dendritic alloy solidification are studied. Numerical simulations are performed using a recently developed multiphase model that accounts for the nucleation and crystal growth mechanisms taking place at various microscopic length scales, as well as for flow, heat transfer and solute redistribution at the system scale. The predictions are compared to experiments carried out in a square test cell using the transparent NH{sub 4}Cl-H{sub 2}O alloy analog. Several important features of equiaxed dendritic solidification are identified, including the grain generation and growth behaviors in the presence of liquid flow, the sedimentation of equiaxed crystals, the formation of a crystal sediment bed, and a bottom zone of negative segregation resulting from the counter-current solid-liquid multiphase flow. Qualitatively good agreement between the measured and predicted cooling curves and evolutions of the crystal sediment bed is achieved. Finally, several areas for future research are indicated.

• OSTI ID: 227781
• Report Number(s): CONF-9509118--; ISBN 0-87339-297-3
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
99 GENERAL AND MISCELLANEOUS
ALLOYS
AMMONIUM CHLORIDES
AQUEOUS SOLUTIONS
BOUNDARY CONDITIONS
CONVECTION
CORRELATIONS
CRYSTAL GROWTH
EXPERIMENTAL DATA
FLUID FLOW
GRAIN SIZE
HEAT TRANSFER
KINETICS
MASS TRANSFER
MATHEMATICAL MODELS
MICROSTRUCTURE
NUCLEATION
SEGREGATION
SIMULATION
SOLIDIFICATION
SOLUTES
VALIDATION