大規模粗視化分子動力学による凝固界面解析

抄録

A coarse-grained (CG) molecular dynamics (MD) model for alloy systems was developed and applied to Al–Cu alloy system. Large-scale CG-MD simulations of crystal growth were systematically conducted under various solute concentrations and temperatures of undercooled melts using a supercomputer. The results showed that, for all concentrations studied, the growth velocity increased with decreasing temperature, reached a maximum at the undercooling of ΔT = 225 K, and then decreased at lower temperatures, yielding a peak-shaped temperature dependence. Regarding morphology, rhombic crystals with strong anisotropy were observed at medium to high temperatures for pure Al and Al–1.3at%Cu, while weakly anisotropic circular crystals formed at the undercooling of ΔT = 275 K. In contrast, Al–3.0at%Cu produced weakly anisotropic structures across all conditions. Despite the reduced resolution inherent in CG compared to all-atom (AA) MD models, performing numerous AA simulations at the micrometer scale remains practically unfeasible even with current supercomputers. This study demonstrates that CG-MD provides a powerful and effective approach for exploring the temperature- and concentration-dependent solidification processes in alloy systems, highlighting its significant potential for large-scale materials simulations.