Combined atomic-scale modelling and experimental studies of nucleation in the solid state

Area of Science:

• Materials Science
• Metallurgy
• Computational Materials Science

Background:

• Solid-state nucleation is critical for controlling alloy microstructures.
• Understanding atomic-scale processes in supersaturated solid solutions is challenging.

Purpose of the Study:

• To investigate solid-state nucleation in supersaturated solid solutions at the atomic scale.
• To develop and validate atomistic models for predicting alloy microstructures.
• To understand solute interactions and their role in precipitate nucleation.

Main Methods:

• Three-dimensional atom probe (3DAP) analysis for atomic-scale imaging.
• Atomistic modeling using dynamical Ising models.
• Development of both simple atom-exchange and vacancy-hopping models.
• Validation against experimental data from binary Cu-Co alloys and complex steels.

Main Results:

• A simple model accurately reproduced microstructures and precipitate density in Cu-Co alloys.
• A sophisticated vacancy-hopping model successfully predicted microstructures in complex steels.
• Observed and modeled the pre-precipitation clustering of Ni and Mn.
• Demonstrated that solute clusters act as nucleation sites for Cu precipitates.
• Revealed that Ni and Mn clustering occurs during alloy cooling.

Conclusions:

• Combined atom probe analysis and atomistic modeling provide atomic-scale insights into nucleation.
• Sophisticated models are necessary for complex alloys with multiple solute interactions.
• Solute clustering significantly influences heterogeneous nucleation of precipitates.
• This approach is essential for controlling fine-scale microstructures in advanced engineering alloys.