In this work, the effects of aluminum carbide (Al 4 C 3 ) on the mechanical properties and thermal behaviors of Al based composites reinforced by SiC and carbon nanotubes (CNTs) were investigated. The formation of Al 4 C 3 was precisely controlled in the temperature range from 530 °C to 630 °C (80%–95% of the Al melting point) during the post heat treatment. Microscopy observations revealed that Al 4 C 3 rods are originated from CNTs instead of SiC particles. Quantity and size of Al 4 C 3 are highly dependent on the heat treatment temperature. It was found that the mechanical properties of the Al based composites were significantly affected by the size of Al 4 C 3 . Moreover, the formation of Al 4 C 3 helps to decrease the coefficient of thermal expansion (CTE) of the composites due to the consumption of Al and the enhanced interfacial bonding . This study provides a potential approach for ameliorating the mechanical and thermal performances of CNTs reinforced metal matrix composites .
Impedance mismatch and high-temperature oxidation are two main factors that limit the practical application of carbon-based absorbing materials. Although micro/nano-structured composites have been explored to alleviate these issues, they often suffer from dispersion instability and structural fragility. In this work, a coaxial composite fiber microwave absorber (Al 4 C 3 /Al 2 O 3 @C f ) is fabricated using carbon fiber (C f ) as a template and conductive core, with an Al 4 C 3 /Al 2 O 3 ceramic shell grown in situ via a vapor–solid reaction. Compared to pristine C f , which exhibits negligible absorption, the optimized composite achieves a minimum reflection loss of −49.27 dB, attributed to interfacial polarization and a built-in capacitor-like structure. Meanwhile, the material also features excellent oxidation resistance and thermal insulation (0.0567 W m −1 K −1 at 100 °C). This study presents a structurally controllable, thermally robust absorber design that overcomes key limitations of traditional carbon-based materials, offering a promising solution for next-generation electromagnetic protection in aerospace and harsh environments.
This research presents an approach for C-O grain boundary strengthening of Al composites that used an in situ method to synthesize a C-O shell on Al powder particles in a vertical tube furnace. The C-O reinforced Al matrix composites (C-O/Al composites) were fabricated by a new powder metallurgy (PM) method associated with the hot pressing technique. The data indicates that Al4C3was distributed within the Al matrix and an O-Al solution was distributed in the grain boundaries in the strengthened structure. The formation mechanism of this structure was explained by a combination of TEM observations and molecular dynamic simulation results. The yield strength and ultimate tensile strength of the C-O/Al composites, modified by 3 wt.% polyvinyl butyral, reached 232.2 MPa and 304.82 MPa, respectively; compared to the yield strength and ultimate tensile strength of the pure aluminum processed under the same conditions, there was an increase of 124% and 99.3%, respectively. These results indicate the excellent properties of the C-O/Al-strengthened structure. In addition, the strengthening mechanism was explained by the Hall–Petch strengthening, dislocation strengthening, and solid solution strengthening mechanisms, which represented contributions of nearly 44.9%, 15.9%, and 16.6% to the total increased strength, respectively. The remaining increment was attributed to the coupled strengthening of the C and O, which contributed 20.6% to the total increase.
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