Simulation of the θ' Precipitation Process with Interfacial Anisotropy Effects in Al-Cu Alloys

Area of Science:

• Materials Science
• Computational Materials Science
• Physical Metallurgy

Background:

• Understanding precipitate growth and ripening is crucial for tailoring alloy properties.
• Anisotropic interfacial properties and heterogeneous elasticity are key factors influencing precipitate morphology.
• Previous studies on similar alloys have shown complex precipitation behaviors.

Purpose of the Study:

• To investigate the effects of anisotropic interfacial properties and heterogeneous elasticity on the growth and ripening of plate-like θ'-phase precipitates in Al-Cu alloys.
• To compare simulation results with experimental observations to validate the model.
• To elucidate the role of chemo-mechanical coupling in precipitation phenomena.

Main Methods:

• Multi-phase-field simulations incorporating anisotropic interfacial energy and mobility.
• Inclusion of elastic anisotropy and chemo-mechanical coupling (composition-dependent elastic constants).
• Comparison of simulation outcomes with experimental aging data of Al-1.69 at.% Cu alloy.

Main Results:

• Anisotropic interfacial mobility combined with elastic anisotropy significantly increases precipitate aspect ratios, aligning with experimental data.
• Interfacial energy anisotropy has a minor effect on aspect ratio but influences rim shape.
• Inverse ripening, observed in other precipitate systems, does not occur for θ' precipitates due to anisotropic stress fields.

Conclusions:

• Anisotropic interfacial mobility and elastic anisotropy are critical for accurately modeling θ' precipitate growth and morphology in Al-Cu alloys.
• Chemo-mechanical effects on precipitation ripening are strongly dependent on the precipitate's shape and the elastic isotropy of the system.
• The study provides insights into the fundamental mechanisms governing precipitation in metallic alloys.