Scandium Microalloying for Al-Cu-Mg-Mn-Ti Alloys with High Cu Content

Area of Science:

• Materials Science
• Metallurgy
• Alloy Development

Background:

• High copper (Cu) content in aluminum alloys enhances strength but degrades casting performance due to a widened solidification range.
• Improving the mechanical properties and castability of high-Cu Al alloys remains a challenge for wider applications.

Purpose of the Study:

• Investigate the impact of scandium (Sc) content on the microstructure and mechanical properties of Al-Cu-Mg-Mn-Ti alloys with high Cu.
• Determine the optimal Sc addition for enhancing alloy performance.

Main Methods:

• Systematic variation of Sc content in Al-8.5Cu-0.3Mg-0.35Mn-0.2Ti alloys.
• Analysis of microstructural changes, including primary phase and grain size.
• Evaluation of tensile strength at room temperature and 350 °C.

Main Results:

• The primary phase transitions from α-Al to Al3Sc at approximately 0.37% Sc.
• The alloy's grain size is minimized at 0.3 wt.% Sc addition.
• Tensile strength at room temperature increased by 14.0% (327.2 MPa) and at 350 °C by 24.5% (103 MPa) with 0.3 wt.% Sc.

Conclusions:

• Scandium addition refines grains in high-Cu Al alloys by forming Al3Sc nucleation sites.
• Sc-containing precipitates may enhance high-temperature strength.
• Optimizing Sc content significantly improves both microstructure and mechanical properties, particularly tensile strength at elevated temperatures.