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Microstructural and Mechanical Characterization of Al Nanocomposites Using GCNs as a Reinforcement Fabricated by
Verónica Gallegos Orozco1,2, Audel Santos Beltrán1, Miriam Santos Beltrán1
1Departamento de Nanotecnología, Universidad Tecnológica de Chihuahua Sur, Km. 3.5 Carr. Chihuahua a Aldama, Chihuahua 31313, Mexico.
International Journal of Molecular Sciences
|March 29, 2023
Summary
High-energy ball milling effectively dispersed carbon graphite nanostructures (CGNs) in an aluminum matrix. Rapid sintering via high-frequency induction sintering (HFIS) prevented undesirable phase precipitation, enhancing material properties.
Area of Science:
- Materials Science
- Nanotechnology
- Mechanical Engineering
Background:
- High-energy ball milling enables controlled microstructure production in composite powders.
- Achieving homogeneous distribution of reinforcements in a metal matrix is crucial for material properties.
- In situ production of nanostructured graphite reinforcements within an aluminum matrix presents unique fabrication challenges.
Purpose of the Study:
- To fabricate Al/CGNs nanocomposites using high-energy ball milling.
- To investigate the role of high-frequency induction sintering (HFIS) in preventing Al4C3 phase precipitation.
- To evaluate the strengthening mechanisms and contributions of dispersed CGNs and dislocation density in the Al matrix.
Main Methods:
- Fabrication of Al/CGNs nanocomposites via high-energy ball milling.
- Sintering using high-frequency induction sintering (HFIS) and conventional electric furnace (CFS) for comparison.
- Microhardness testing to assess reinforcement effectiveness.
- X-ray diffraction with convolutional multiple whole profile (CMWP) fitting for crystallite size and dislocation density analysis.
- Atomic force microscopy (AFM) and scanning electron microscopy (SEM) for microstructural and morphological analysis.
Main Results:
- High-energy ball milling promoted increased dislocation density in the Al matrix due to CGN dispersion.
- HFIS effectively retained dispersed CGNs, avoiding Al4C3 phase precipitation during sintering.
- Dislocation density contributed approximately 50% to the total hardening, while CGN dispersion contributed about 22% in HFIS-sintered samples (3 wt.% C).
- AFM analysis revealed CGNs primarily located around crystallites with height profiles of 1.6-2 nm.
Conclusions:
- Al/CGNs nanocomposites fabricated via high-energy ball milling and HFIS exhibit enhanced mechanical properties.
- Dislocation strengthening is a significant contributor to the overall hardening in these nanocomposites.
- The dispersion of CGNs plays a vital role in reinforcing the aluminum matrix, with HFIS being critical for preserving this reinforcement.
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