In-situ synthesis of Al-Si/SiC nanocomposite via combined mechanical milling and sintering
SiC-reinforced aluminum composites are suitable for applications that require high mechanical strength. Recent studies suggest that Al4C3 is a promising precursor for the in-situ formation of SiC in Al-SiC composites, enhancing interfacial bonding. SiC particles synthesized from Al4C3 tend to form c...
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| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Elsevier
2025-08-01
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| Series: | Heliyon |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2405844025021450 |
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| Summary: | SiC-reinforced aluminum composites are suitable for applications that require high mechanical strength. Recent studies suggest that Al4C3 is a promising precursor for the in-situ formation of SiC in Al-SiC composites, enhancing interfacial bonding. SiC particles synthesized from Al4C3 tend to form clean, coherent interfaces with the aluminum matrix. This study presents a novel three-step in-situ synthesis route for fabricating Al-Si/SiC nanocomposites with high mechanical strength using commercial pure aluminum, graphite, and silicon powders. The process involves two-step mechanical milling, cold pressing, and two-step sintering. In the first stage, Al and 5 wt% graphite were milled and sintered at 750 °C to form Al4C3. In the second stage, the Al–Al4C3 powder was further milled with silicon and sintered at 1000 °C, enabling a solid-state reaction between Al4C3 and Si to produce in-situ SiC. The novelty of this approach lies in utilizing Al4C3 as an intermediate phase to synthesize SiC nanoparticles with clean, coherent interfaces within the aluminum matrix. Phase formation and microstructure evolution were investigated by XRD, SEM, EDS, and HRTEM analyses. The formation of SiC was confirmed after 18 h of second-step mechanical milling. The synthesis of SiC was further developed by subsequent sintering at 1000 °C. Mechanical testing revealed a significant increase in hardness, from ∼330 HV after 6 h of milling to ∼415 HV after 24 h, attributed to enhanced in-situ SiC formation. Mechanical alloying activates the soft Al powders and embedded graphite particles into the Al matrix. During sintering, the Al matrix partially melted, and the graphite powders reacted with the surrounding melted Al to form Al4C3. The Al-Si/Al4C3 formed by adding silicon. Ball milling in this stage caused fractures in the hard Al4C3 and silicon particles. After 18 h of ball milling, a solid-state reaction may occur at the interface between the surfaces of Al4C3 and Si particles, resulting in the formation of SiC. When the temperature was increased, Al4C3 and Si reacted to form SiC and Al. Overall, this method illustrates a strategically designed in-situ reaction route using Al4C3 as an intermediate phase for SiC synthesis, offering an effective and scalable method for producing high-strength Al-based nanocomposites without the need for externally added SiC. |
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| ISSN: | 2405-8440 |