Processing Optimization of Sustainable AA6061-Fly Ash Composites by Compocasting

Area of Science:

• Materials Science and Engineering
• Metallurgy
• Composite Materials

Background:

• Fly ash, an industrial byproduct, shows promise as a reinforcement for aluminum matrices.
• Conventional stir casting methods often result in poor particle dispersion and weak interfaces in aluminum matrix composites.

Purpose of the Study:

• To fabricate and characterize AA6061/fly ash composites using compocasting.
• To evaluate the microstructural, mechanical, and interfacial properties of these composites.
• To compare the performance of compocast composites with those produced by stir casting.

Main Methods:

• Fabrication of AA6061/fly ash composites (4-12 wt.% fly ash) via compocasting.
• Material characterization using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), fractography, hardness testing, and tensile testing.
• Statistical analysis of reproducibility using Analysis of Variance (ANOVA).

Main Results:

• XRD confirmed the absence of interfacial reaction products.
• SEM revealed uniform fly ash particle dispersion (20-50 μm), pore-free interfaces, and grain refinement.
• Microhardness doubled (55 HV to 110 HV), and ultimate tensile strength increased by 78% (140 MPa to 249 MPa).
• Ductility decreased from 14% to 5%, with fractography indicating robust interfacial bonding.
• Compocasting demonstrated superior dispersion, lower porosity, and cleaner interfaces compared to stir casting.

Conclusions:

• Compocasting is a viable method for producing AA6061/fly ash composites with enhanced mechanical properties.
• The process leads to a refined microstructure and improved strength and hardness.
• Fly ash can be effectively valorized as a reinforcement for lightweight, high-strength applications in automotive and aerospace industries.