Pattern Formation under Deep Supercooling by Classical Density Functional-Based Approach.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Crystallography

Background:

• Nonequilibrium crystallization produces critical microstructures in nature and technology.
• Understanding atom-level crystal growth in deeply supercooled liquids is essential.

Purpose of the Study:

• Investigate crystal growth dynamics in deeply supercooled liquids.
• Develop and validate a novel computational model for nonequilibrium crystallization.

Main Methods:

• Utilized classical density functional-based approaches.
• Employed a complex amplitude expanded phase-field crystal (APFC) model incorporating vacancy nonequilibrium effects.
• Simulated atom-level crystal growth processes.

Main Results:

• The proposed APFC model successfully reproduced growth front nucleation (GFN) and diverse patterns like dendrites and spherulites.
• Discovered a microscopic columnar-to-equiaxed transition dependent on seed characteristics, attributed to elastic interactions.
• Identified two growth stages: diffusion-controlled and GFN-dominated, with the latter showing significant lattice defect increments.

Conclusions:

• The APFC model with vacancy nonequilibrium effects provides a robust framework for studying complex solidification phenomena.
• The uncovered columnar-to-equiaxed transition offers new insights into microstructure formation.
• Lattice defect generation during GFN-dominated growth explains amorphous nucleation precursors.