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Nanocarbon 2024 aluminum composites with 0.5 vol. % and 1 vol. % of graphene nanoplatelets and 1 vol. % and 2 vol. % of activated nanocarbon were manufactured through induction casting. The effect of the reinforcements and heat treatment on the performance of the composites was examined. Analysis of the microstructure of the composites before heat treatment suggested the homogeneous dispersion of reinforcements and the absence of secondary carbide or oxide phases. The presence of carbon nanoparticles had a significant impact on the microstructural characteristics of the matrix. This behavior was further enhanced after the heat treatment. The mechanical and damping properties were evaluated with the uniaxial compression test, micro Vickers hardness test, and dynamic mechanical analysis. The yield strength and ultimate strength were improved up to 28% (1 vol. % of graphene nanoplatelets) and 45% (0.5 vol. % of graphene nanoplatelets), respectively, compared to the as-cast 2024 aluminum. Similarly, compared to the heat-treated 2024 aluminum, the composites increased up to 56% (0.5 vol. % of graphene nanoplatelets) and 57% (0.5 vol. % of graphene nanoplatelets) in yield strength and ultimate strength, respectively. Likewise, the hardness of the samples was up to 33% (1 vol. % of graphene nanoplatelets) higher than that of the as-cast 2024 aluminum, and up to 31% (2 vol. % of activated nanocarbon) with respect to the heat-treated 2024 aluminum. The damping properties of the nanocarbon–aluminum composites were determined at variable temperatures and strain amplitudes. The results indicate that damping properties improved for the composites without heat treatment. As a result, it is demonstrated that using small volume fractions of nanocarbon allotropes enhanced the mechanical properties for both with- and without-heat treatment with a limited loss of plastic deformation before failure for the 2024 aluminum matrix.
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This content will become publicly available on January 25, 2026
Insights into the gamma prime precipitation behavior during heat treatment of additively manufactured nickel-based superalloy
The presence of higher vol% of gamma prime (γ′) in Nickel-based superalloys is crucial for achieving superior high-temperature strength and creep resistance properties. While directed energy deposition (DED) offers promising solutions for repairing these alloys, they usually lack the precipitation of γ′ phases due to rapid solidification. This study investigates the precipitation behavior in DED-produced Inconel 100 (IN100) superalloy during as-deposited and post-heat treatment conditions, focusing on the evolution of γ′ morphology, size, volume fraction, and their correlation with mechanical properties. Results obtained from the combination of experimental studies and CALPHAD-based thermodynamic simulations in as-deposited conditions showed the presence of a γ matrix with MC carbides (rich in Ti and Mo) and eutectic γ/γ' phases in the interdendritic region, which are deleterious to mechanical properties. A subsequent post-heat treatment dissolved these intermetallic phases and improved the vol% of γ′. The solution heat treatments form the γ' in complex structures, following the Ostwald ripening and reverse coarsening effects, where γ' was observed in spherical (< 0.1 μm), cubic (0.1–0.5 μm), and octet (> 0.5 μm) shapes. One-step age hardening significantly increased the volume fraction of γ′, changing the γ′ morphology to cubes. The presence of γ′ was further enhanced during a 2-step age hardening with the precipitation of secondary γ′. The γ′ precipitation behavior was statistically quantified using advanced digital image analysis protocols and analyzed using Gaussian Mixture Models (GMM). The findings offer valuable insights into tailoring microstructure and enhancing precipitation strengthening in AM IN100, with potential benefits for high-temperature aerospace applications.
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- Award ID(s):
- 2027105
- PAR ID:
- 10591191
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Journal of Alloys and Compounds
- Volume:
- 1012
- Issue:
- C
- ISSN:
- 0925-8388
- Page Range / eLocation ID:
- 178507
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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