M.Tech(Res) Thesis Defence: Mr. Shubham P. Karmokar (30/07/26)
Thesis title:
Domain-dependent Solidification Microstructure Selection Maps and Columnar to Equiaxed Transition: A Cellular Automata Study
Faculty advisor(s):
Dr. Pikee Priya
When?
30th July, 2026 (Thursday), 09:00 AM (India Standard Time)
Where
KPA Auditorium, Department of Materials Engineering(hybrid mode)
Abstract
Rapid solidification during additive manufacturing (AM) occurs under highly transient thermal conditions that differ substantially from the assumptions underlying classical dendritic growth theories. Models such as the Lipton–Glicksman–Kurz (LGK) and Kurz–Giovanola–Trivedi (KGT) formulations have been widely used to describe dendrite growth and to construct solidification microstructure selection maps (SMSMs), yet their applicability under finite-domain, rapidly evolving thermal conditions remains insufficiently examined.
This thesis develops a Cellular Automata (CA) framework coupled with LGK and KGT dendrite growth kinetics to investigate microstructure evolution over thermal conditions spanning conventional casting to additive manufacturing. The framework is used to study isolated equiaxed growth, competitive growth between columnar and equiaxed dendrites, and the resulting columnar-to-equiaxed transition (CET). Numerical simulations are further employed to construct SMSMs using experimentally measurable thermal gradient and cooling rate, under different growth models and domain sizes.
The simulations show that finite domain size, transient thermal histories, dendrite morphology, and interface kinetics significantly influence grain growth characteristics and the predicted location of microstructure regime boundaries. In particular, the results demonstrate that SMSMs derived under conventional steady-state assumptions can shift appreciably under AM-relevant conditions, with the magnitude of these shifts depending on both growth kinetics and system dimensions. Based on these observations, modifications to the conventional CET framework are explored to account for finite-domain effects within the limitations of the present model.