Microstructure, Properties, and Numerical Simulation of Semi-Solid Aluminum Alloy under Planetary Stirring Process

Area of Science:

• Materials Science
• Metallurgy
• Computational Fluid Dynamics

Background:

• Uniaxial stirring of melts exhibits insufficient convective heat transfer.
• Semi-solid metal processing requires precise temperature control for optimal microstructure.

Purpose of the Study:

• To investigate the temperature field and shear rate of melts under planetary stirring.
• To compare the convective heat transfer of planetary stirring with uniaxial stirring.
• To evaluate the impact of planetary stirring on microstructure and properties of semi-solid aluminum alloys.

Main Methods:

• Computational Fluid Dynamics (CFD) simulations were employed to study the temperature field and shear rate.
• Experimental studies were conducted to analyze the microstructure and properties of the processed materials.

Main Results:

• Planetary stirring demonstrates stronger convective heat transfer compared to uniaxial stirring for semi-solid aluminum alloy slurries.
• Planetary stirring achieves faster and more uniform temperature reduction into the semi-solid range, promoting nucleation and increasing nucleation rate.
• Reduced temperature differences in the melt under planetary stirring prevent preferred direction and uniform dendrite growth, improving overall morphology.
• Optimized revolution and rotation speeds refine grain size and improve grain morphology, leading to enhanced tensile strength.

Conclusions:

• Planetary stirring significantly improves heat transfer and temperature uniformity in semi-solid metal processing.
• The refined grain structure and improved morphology result in enhanced mechanical properties of semi-solid aluminum alloys.
• The planetary stirring semi-solid process is highly suitable for rheological high-pressure casting applications.