High Strain Rate Superplasticity in Al-Zn-Mg-Based Alloy: Microstructural Design, Deformation Behavior, and Modeling

Area of Science:

• Materials Science
• Metallurgy
• Mechanical Engineering

Background:

• Superplastic forming of aluminum alloys is crucial for manufacturing but limited by strain rate challenges.
• Achieving high strain rate superplasticity is essential for economic and technical advancements in aluminum forming.

Purpose of the Study:

• To develop and characterize a novel Al-Zn-Mg-based alloy with enhanced superplasticity at high strain rates.
• To investigate the microstructure and superplastic properties of the new alloy under various strain rates.

Main Methods:

• Thermomechanical treatment involving hot and cold rolling was applied to the Al-Zn-Mg-based alloy.
• Microstructural analysis focused on coarse Al3Ni particles and L12-Al3(Sc,Zr) nanoprecipitates.
• Superplastic properties were evaluated through elongation tests at strain rates from 0.01 to 1 s⁻¹.
• Mathematical modeling using an Arrhenius-type constitutive model and an artificial neural network was employed.

Main Results:

• The alloy exhibited significant superplasticity with elongations of 600-800% at strain rates of 0.01-0.6/s and low residual cavitation (<2%).
• An impressive mean elongation-to-failure of 400% was achieved at an extremely high strain rate of 1 s⁻¹.
• Dynamic recrystallization was confirmed during superplastic deformation.
• Both constitutive and neural network models demonstrated high predictability for the alloy's flow behavior.

Conclusions:

• The developed Al-Zn-Mg-based alloy demonstrates excellent high strain rate superplasticity, overcoming previous limitations.
• The unique combination of coarse Al3Ni particles and L12-Al3(Sc,Zr) nanoprecipitates contributes to the observed superplastic behavior.
• The validated predictive models offer valuable tools for optimizing superplastic forming processes using this new alloy.