Additively Manufacturable High-Strength Aluminum Alloys with Coarsening-Resistant Microstructures Achieved via Rapid...

Area of Science:

• Materials Science
• Metallurgy
• Additive Manufacturing

Background:

• High-strength aluminum (Al) alloys are crucial for industrial applications.
• Achieving high strength requires fine, closely spaced precipitates to hinder dislocation movement.

Purpose of the Study:

• To design and develop novel additively manufactured aluminum alloys with enhanced strength.
• To investigate the precipitation behavior of L12-Al3M phases during additive manufacturing and heat treatment.

Main Methods:

• Utilized hybrid calculation of phase diagrams (CALPHAD)-based integrated computational materials engineering (ICME) and Bayesian optimization for alloy design.
• Employed powder bed additive manufacturing for creating crack-free specimens.
• Conducted heat treatment and room-temperature tensile testing to evaluate mechanical properties.

Main Results:

• Identified L12-Al3M phases precipitating as metastable ternary phases under rapid solidification.
• Achieved nanometer-scale coarsening-resistant L12-Al3M phases during heat treatment, imparting high strength.
• Developed an alloy with five-fold the strength of the cast equivalent, reaching 395 MPa tensile strength after aging, surpassing benchmark printable Al alloys.

Conclusions:

• The integrated computational-experimental workflow demonstrates the potential of rapid solidification in additive manufacturing for designing high-performance alloys.
• The developed aluminum alloy exhibits commercially deployable properties, comparable to wrought Al 7075.
• This approach offers a pathway to create advanced aluminum alloys with superior mechanical characteristics.