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)

Nucleation of crystalline materials, the starting point for crystal formation from melts, has long been an important issue in condensed matter physics and materials science. Nucleation plays a key role in determining the microstructures and mechanical properties of crystalline materials; therefore, controlling nucleation is a very effective way for regulating the macrostructures of materials for specific applications. As nucleation occurs at atomic length scales and diffusional time scale, it is still hard to investigate such kind of multiple scale issue with regular methods. Classical nucleation theory (CNT) can descript nucleation issues well, however, it does not take the lattice structure transition during nucleation into consideration, which makes CNT can’t descript crystal nucleation quantitatively. Further, more and more investigations reported that nucleation often pass through some intermediate states, and the properties of the intermediate phases has significant influence on nucleation pathways. This kinds of nucleation often calls two-step nucleation (TS), however, the atomistic pathways of TS still unknown. A deeper understanding of nucleation process requires experimental or numerical work to provide atomistic visualizations and images of nucleation. In this dissertation, both the Phase field crystal model and Molecular dynamic method are employed to study the nucleation pathways and pathway selection mechanisms on atomistic scales for both single phase and binary alloy solidification.