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)

Recently, Additive manufacturing (AM) has emerged as a disruptive technology to manufacture complex parts with greater scales of economy and also with a reduced need for post-machining. However, the influence of processing conditions and the alloy compositions on the strength, defect formation are not yet fully understood. A quantitative simulation of the microstructure morphologies and segregation patterns for a given alloy composition will help towards a better prediction of the physical and mechanical properties of the developed part. More particularly, properties such as the susceptibility to solidification cracking are directly related to the segregation behavior as well as the structure of dendritic network in the mushy zone. In this work, a Cellular Automata based three-dimensional (3D) model was developed to simulate dendritic growth for the case of AM. The Thermocalc database was used to obtain the equilibrium multi-component phase diagram. Finite Difference schemes were used to obtain the temporal and concentration fields in the computational domain. The interface velocity and concentrations were obtained by simultaneously solving the corresponding Stefan conditions for individual components along with the Gibbs-Duhem condition assuming local equilibrium at the interface. A height-function based curvature technique was used to accurately estimate the curvature of the sharp interface. In order to achieve a nearly grid-independent growth in any specified crystallographic direction, a decentered-cube algorithm was incorporated. The model validation was performed by comparing the velocity and tip radius selection with analytical relations based on the marginal stability criterion as well as simulations results obtained using the phase-field method. Further, the code was parallelised using MPI libraries, thus enabling it to be run on larger domains. Multi-dendrite simulations were carried out under directional solidification corresponding to AM conditions. The dendrite morphology, orientation and primary arm spacing selection were studied for different cooling rates and thermal gradients. This model can be used to simulate microstructure evolution for generic two-phase alloys under AM conditions.