Diffusion in Al-Cu melts studied by time-resolved X-ray radiography.

Area of Science:

• Materials Science
• Physical Chemistry
• Metallurgy

Background:

• Understanding interdiffusion is crucial for designing alloys and predicting material behavior.
• Existing models often relate interdiffusion to self-diffusion and thermodynamic driving forces.
• In situ monitoring of liquid alloys provides direct insights into diffusion mechanisms.

Purpose of the Study:

• To quantitatively measure interdiffusion coefficients in Al-rich Al-Cu melts.
• To investigate the temperature and composition dependence of interdiffusion.
• To evaluate the relationship between interdiffusion and self-diffusion in these alloys.

Main Methods:

• Utilized time-resolved X-ray radiography for in situ monitoring of interdiffusion.
• Measured temperature and composition-dependent interdiffusion coefficients (D{AlCu}).
• Analyzed Al-rich Al-Cu liquid alloy systems.

Main Results:

• Interdiffusion coefficients (D{AlCu}) showed weak dependence on alloy composition at constant temperature.
• Interdiffusion was enhanced by approximately a factor of 3 compared to self-diffusion.
• Observed discrepancies challenge the direct expression of interdiffusion via self-diffusion and thermodynamic forces.

Conclusions:

• The study provides novel in situ measurements of interdiffusion in liquid Al-Cu alloys.
• Results indicate that interdiffusion in these systems is not simply a function of self-diffusion and thermodynamic driving forces.
• Further theoretical development is needed to accurately model interdiffusion in liquid alloys.