Revealing Solute Clusters in Coalescence by Atom Probe Tomography Analysis

Area of Science:

• Materials Science
• Metallurgy
• Physical Chemistry

Background:

• Understanding solute cluster evolution is crucial for alloy performance.
• Experimental investigation of solute cluster coalescence has been limited.
• Atom Probe Tomography (APT) offers high-resolution insights into nanoscale phenomena.

Purpose of the Study:

• To experimentally investigate the dynamic evolution and growth behavior of small solute clusters in alloys.
• To address the challenge of experimentally studying solute cluster coalescence.
• To quantify the contribution of coalescence to cluster growth in Al–Zn–Mg alloys.

Main Methods:

• Utilized Atom Probe Tomography (APT) to analyze solute cluster boundaries and identify clusters in close proximity.
• Employed the maximum separation method for cluster identification within APT datasets.
• Systematically tracked the population and size evolution of coalescing clusters over aging time.

Main Results:

• Demonstrated that cluster coalescence significantly contributes to the growth of small solute clusters.
• Identified coalescence as the predominant mechanism for the formation and growth of large Guinier–Preston II (GP II) zones.
• Observed these effects in naturally aged Al–Zn–Mg alloys after 3 months of aging.

Conclusions:

• Coalescence is a key, experimentally verifiable mechanism driving solute cluster growth in alloys.
• The findings provide critical insights into the precipitation kinetics of GP II zones in Al–Zn–Mg alloys.
• This work establishes APT as a powerful technique for studying cluster coalescence dynamics.