Kinetic transition in the order-disorder transformation at a solid/liquid interface

Area of Science:

• Materials Science
• Solid State Physics
• Crystallography

Background:

• Understanding kinetic transitions in crystal growth is crucial for materials science.
• Ordered crystal structures exhibit complex growth dynamics influenced by undercooling and atomic diffusion.
• Non-equilibrium phenomena like solute and disorder trapping significantly impact crystal growth velocity and structure.

Purpose of the Study:

• To perform a phase-field analysis of the kinetic transition in ordered crystal growth from an undercooled liquid.
• To interpret results using analytical and numerical solutions for phase field dynamics, order parameter, and atomic diffusion.
• To define critical undercoolings for changes in growth velocity and long-range order parameter in binary alloys.

Main Methods:

• Phase-field modeling to simulate crystal growth dynamics.
• Analytical and numerical solutions of governing equations for phase field, order parameter, and diffusion.
• Case study of a binary A50B50 crystal growth.

Main Results:

• Defined critical undercoolings for characteristic changes in growth velocity and long-range order parameter.
• Identified analogies and differences with non-equilibrium effects (solute trapping, disorder trapping) for rapidly growing crystals.
• Qualitative comparison of model predictions with Chernov's kinetic phase transition theory and experimental data for alloy solidification.

Conclusions:

• The phase-field model provides insights into kinetic transitions during ordered crystal growth.
• Results offer a framework for understanding non-equilibrium effects in crystal solidification.
• The study validates model predictions against established theories and experimental observations.