Modeling of heat flow during solidification and melting in a differential thermal analyzer (DTA)

Book · Sun Dec 31 04:00:00 EST 1995

OSTI ID:227775

Banerjee, D K ^[1]; Boettinger, W J; Schaefer, R J; Williams, M E ^[2]

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1. UES, Inc., Annapolis, MD (United States)
2. National Inst. of Standards and Technology, Gaithersburg, MD (United States). Metallurgy Div.

DTA (Differential Thermal Analysis) results are widely used to obtain information regarding the solidification behavior of alloys. For example, liquidus and solidus temperatures are extracted from data collected during heating, and undercooling behavior prior to solidification is obtained during cooling. The accuracy of these measurements can greatly influence the predictions of microstructural models of castings employing these data or laws derived from these data. In traditional DTA experiments, thermocouples are not in direct contact with the alloy but are separated from it by a thin crucible. Therefore, the thermal events occurring in the alloy can only be indirectly inferred from the response of thermocouples. In order to gain insight into this thermal response and provide a more accurate interpretation of DTA results in general, numerical heat flow modeling of melting and solidification in a DTA has been performed. By comparing calculated thermocouple response with the experimental DTA results for the melting of pure Ni, the various heat transfer coefficients between the different materials in the DTA setup have been adjusted. Examples of the DTA signal for IN718 are then calculated for a specific fraction solid vs. temperature relationship and also using a micromodel that includes nucleation, dendrite tip growth, and undercooling.

• OSTI ID: 227775
• 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
CORRELATIONS
EXPERIMENTAL DATA
FINITE ELEMENT METHOD
HEAT TRANSFER
HEATING RATE
INCONEL 718
LIQUID METALS
MASS
MATHEMATICAL MODELS
MELTING
NICKEL
SIMULATION
SOLIDIFICATION
TEMPERATURE DEPENDENCE
THERMOCOUPLES
TIME DEPENDENCE