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)

The solidification of alloys shows a large variety of different microstructures depending on the material system and processing conditions. Since materials properties such as tensile strength are dependent on the microstructure, its prediction is a topic of high interest in order to produce materials with tailored properties. Whereas theory is capable of investigating simple geometries, simulations are utilized to ascertain the influence of processing conditions on complex evolving geometries. An example of this is the coupled growth of dendrites and eutectics, which typically evolve at different length scales. % irgendiwe ohne example schreiben In order to simulate this coupled growth, the phase-field method is chosen as it has been established as a versatile tool to investigate microstructural evolution. The phase-field model is based on a grand potential approach with parabolic free energies approximating thermodynamic CALPHAD data of the system Al-Cu. With this the coupled growth of coarse dendrites and fine eutectics during directional solidification is investigated in two as well as three dimensional simulations. Depending on the process parameters, observations include: Closely-spaced dendrites turning into cells, stable coupled dendritic-eutectic growth, nucleation of eutectics on dendritic sidebranches as well as transitions to a completely eutectic state. Based on these results a tentative microstructure map is established. Finally, the influence of the dendritic growth direction on the microstructure is investigated.