[SY-M2] Atomic analysis of crystalline nucleation and growth in the supercooled liquid of glass-forming binary alloy
Microstructures of solid metals is significantly affected by solidification process from liquid melts. In special, nucleation and growth of crystalline nucleus in supercooled liquid dominates the glass forming ability of amorphous metals or microstructures of crystalline metals. However, key factors affecting nucleation and growth of crystalline nucleus are still under discussion. In experiments, unveiling the nucleation and growth processes is difficult due to limitation of observable time- and space-scale resolution. On the other hand, atomic simulation such as molecular dynamics (MD) has a difficulty to investigate the crystallization of alloys from liquid state, because the time-scale of the crystallization of alloys is generally beyond the time-scale of atomic simulation. In order to provide atomistic knowledge of the solidification of liquid metal, we in this study focus on the feature of crystalline nucleus in the supercooled liquid metals. First, we prepared atomic models of glass-forming binary alloy, in which a spherical crystal nucleus is embedded in advance. The size of embedded nucleus is smaller than the critical nucleus size. Then we conducted MD simulation under the NPT condition at supercooled liquid temperature under the constraint of nucleus radius: the constraint is realized by adding a boost potential to the liquid-crystal composite model. During MD simulations, we evaluated the crystal nucleus from geometrical and statistical aspects. The obtained results provide the atomistic insight into the early stage of crystallization of metal.