| Abstract | This study investigates the microstructural characteristics and fracture behavior of the AlSi10MnMg structural alloy under different processing conditions in high-pressure vacuum die casting (HPVDC). The research specifically focuses on the effects of externally solidified crystals (ESCs) and Fe-rich intermetallic compounds (Fe-IMCs) on mechanical performance. Thin-walled prototypes were produced with varying conditions, including Fe content, recycled feed, die lubrication, and melt temperature, which significantly influenced tensile ductility at room temperature. Variant A, characterized by a higher recycled feed, lower melt temperature, and slightly higher Fe content, exhibited reduced elongation at fracture. In contrast, Variant B, produced with a lower recycled feed fraction, higher melt temperature, and lower Fe content, achieved typical elongation values. Comprehensive microstructural analysis using optical and scanning electron microscopies revealed that, while the eutectic and primary aluminum fractions remained comparable across variants, ESC content increased at lower melt temperatures. Two types of Fe-rich intermetallics were identified: large blocky polyhedral particles and smaller compact globular particles. Higher ductility samples exhibited a more uniform distribution of globular particles, whereas lower ductility samples showed increased clustering of particles. The fracture surface analysis indicated that the increased presence of blocky Fe particles, ESCs, and clustered Fe-IMCs facilitated crack initiation and propagation. This led to reduced ductility, as evidenced by cleavage fractures and limited plastic deformation. These findings highlight the significant impact of ESCs and intermetallic particle characteristics on the fracture mechanisms and mechanical performance of AlSi10MnMg aluminum alloys in HPVDC. |
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