5th International Conference on Advances in Solidification Processes (ICASP-5) 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining (CSSCR-5)

We have used high temperature laser-scanning confocal microscopy by utilizing a concentric solidification technique to observe in-situ and in real time solidification events and high-temperature microstructural development, with a special emphasis on high temperature phase transformations. However, the solidification and subsequent solid-state transformation kinetics, on both heating and cooling, are largely determined by the axi-symmetric and dynamically changing temperature profile within the cylindrical specimen, thereby hindering quantitative analysis. We have experimentally determined the temperature distribution and created a simulation domain whereby we can replicate almost exactly the concentric configuration. This combination of thermal analysis with numerical simulations assistance with 3D modeling has enabled us to develop a powerful technique to convert in situ observations into quantitative analysis. We are now able to characterize by numeric modelling, the pertaining solute distribution at different stages of solidification incorporating grain boundary diffusion and maintaining the same solute boundary layer thickness as in the experimental set-up. In the present study, we have carefully defined the domain prior to the solidification, and then compared the numerically calculated solid/liquid interface velocities with the experimental determined values in Fe-0.18C and Fe-4.2Ni alloys at cooling rates that varied from 2K/min to 200K/min. Peritectic reaction kinetics are compared with experimental results for the developed solute profiles at the solid/liquid interface and optimized mobility coefficient between δ/γ . Because we have experimentally determined the pertaining thermal gradients, it is possible to assess thermodynamic parameters at the solid/liquid interface and at triple points using Thermo-Calc. The agreement we obtained between simulation and experimental results, provided us with confidence that the technique can be extended to the quantitative prediction (calculation) of the fundamental thermodynamic parameters pertaining to the concentric solidification platform.