Classical nucleation theory for the crystallization kinetics in sheared liquids.

Area of Science:

• Materials Science
• Thermodynamics
• Computational Physics

Background:

• Predicting phase transformation kinetics is challenging, especially under mechanical stress.
• Classical Nucleation Theory (CNT) models nucleation rates using thermodynamic quantities but its extension to driven systems is unclear.

Purpose of the Study:

• To investigate the impact of mechanical stresses, specifically simple shear, on crystallization kinetics.
• To extend the Classical Nucleation Theory (CNT) framework to accommodate driven melts under shear flow.

Main Methods:

• Numerical simulations of hard spheres subjected to simple shear.
• Extraction of local stress and strain within solid droplets.
• Analysis of size-dependent shear modulus and interfacial work.

Main Results:

• Simple shear's effect on crystallization rate can be explained by an additional elastic work term within CNT.
• Local stress and strain measurements yielded size-dependent shear moduli, approximately half the bulk value.
• Interfacial work changes between strained droplets and sheared liquid are significant for small nuclei.

Conclusions:

• The CNT framework can be extended to rationalize crystallization kinetics in driven melts under shear.
• Elastic work and interfacial work modifications are crucial for accurately describing nucleation under mechanical stress.
• The relative importance of elastic versus interfacial work depends on nucleus size.