Ultra-strong nanotwinned Al-Ni solid solution alloys with significant plasticity

Area of Science:

• Materials Science
• Metallurgy
• Nanotechnology

Background:

• Twin boundaries are crucial for strengthening metallic materials while preserving ductility.
• Aluminum (Al) exhibits limited strengthening via twinning due to its high stacking fault energy.

Purpose of the Study:

• To investigate the effect of nickel (Ni) solutes on the microstructure and mechanical properties of aluminum.
• To explore the potential of creating high-density nanotwins and stacking faults in Al-Ni alloys.

Main Methods:

• Sputtering technique to create Al-Ni solid solution alloys.
• Density Functional Theory (DFT) calculations to understand solute effects.
• In situ micropillar compression testing to evaluate mechanical performance.

Main Results:

• Achieved high-density twin boundaries and stacking faults in Al-Ni alloys using Ni solutes.
• DFT calculations confirmed Ni's role in facilitating stacking faults and stabilizing nanotwins.
• Observed high flow stress (>1.7 GPa) and significant plasticity in the nanotwinned Al-Ni alloy films.

Conclusions:

• Small amounts of Ni solutes effectively induce nanotwinning and stacking faults in Al.
• Nanotwinned Al-Ni alloys exhibit superior strength and ductility, comparable to advanced steels and Ni alloys.
• The presence of twin boundaries and the 9R phase contributes to the enhanced mechanical properties.