Dendritic deformation induced by convection of thermal fluid is one of the factors leading to dendrite fragmentation and plays a crucial role in grain structure of alloy, which remains unclear and lacks of in-depth understandings. In this paper we simulate the flow-induced mechanical deformation of dendrites during solidification of Al-4.5wt.%Cu alloy by combining the cellular automaton - finite volume method (CA-FVM) for the dendrite growth and the finite element method (FEM) for handling the dendritic deformation with the complex boundary conditions given by CA-FVM results. It shows that the dendritic deformation strongly depends on the flow velocities of melt, dendritic structure, and the interactions between dendrite and fluid flow. The dendrites can undergo visible bending above the critical flow velocities (from 0.023 m/s to 0.126 m/s for different dendritic structure) and the stress increases as the flow is enhanced during the growth process. The plastic deformation of the dendrites exhibits a region of strain localization near the root of secondary dendrites and holes formed by the bridging of secondary dendrites. Mechanical fracture of the dendrites can occur from both the fracture stress and fracture strain criteria.

Moderated by: Andre Phillion / Matt Krane