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   COLLOQUIUM OF THE LABORATORY FOR COMPUTER DESIGN OF MATERIALS
                   School of Computational Sciences
                           (CSI 898-Sec 001)
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          Modeling of Solidification and Microsegregation in
                          Multicomponent Alloys

                            Dilip K. Banerjee
                       Advanced Technology Program
    National Institute of Standards and Technology, Gaithersburg, MD

   Numerical modeling of solidification of cast commercial alloys 
requires consideration of solidification path and microsegregation in
multicomponent alloys. An accurate prediction of solidification path 
is needed to compute enthalpy as a function of temperature, which is 
a key input in solidification modeling software. In recent years, a
number of thermodynamic databases have becomecommercially available 
for performing thermodynamic calculations using various 
microsegregation models. The effects of solid diffusion and dendrite 
tip kinetics on primary solidification are described. Predictions 
of solidification path involving multiphase reactions are also 
considered. The integration of this thermodynamic calculation of
temperature-dependent enthalpy and fraction of solid into 
solidification modeling software is discussed. Benefits and 
shortcomings of using this approach in commercial casting 
simulation software are highlighted.

   Use of deterministic micromodels to compute the evolution of 
fraction solid during solidification is also described. Practical 
examples are shown to highlight the capability of these models in 
predicting formation of defects and mechanical properties in cast
components.

                        Monday , March 31, 2003
                              4:30 pm
                        Room 206, Science & Tech. I