Role of supersaturated Al-C phases in mechanical properties of Al/fullerene composites

Seungjin Nam,Aeran Roh,Hansol Son,Sooun Lee,Hyunjoo Choi,Miso Kim

doi:10.1038/s41598-021-92551-y

Seungjin Nam, Aeran Roh + Show 4 more

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https://doi.org/10.1038/s41598-021-92551-y

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Abstract

We investigated the reinforcing effect of supersaturated Al-C phases on the mechanical properties of Al/C60 composites produced via powder metallurgy followed by thermal treatment. We controlled the fractions of C60-fullerenes, nano-scale carbides, and Al-C supersaturated phases in the Al/C60 composites by adjusting the heat-treatment temperature and duration. Furthermore, we examined the contribution of each phase on the elastic and plastic behavior of the composites using scanning acoustic microscopy (SAM) and hardness measurements. After heat treatment, a supersaturated Al-C phase and an Al carbide were formed in the Al/C composites by decomposition of individually dispersed C60. This led to enhancement of the hardness and elastic modulus of the Al/C composites heat-treated at 450 and 500 °C, while these properties were reduced in the 650 °C heat-treated composite. Notably, the 500 °C heat-treated composites showed significantly high hardness and elastic modulus (approximately 250 Hv and 77.8 GPa, respectively) owing to the substantially large contribution of the supersaturated Al-C phases, which was theoretically calculated to be 851 GPa/vol% and 227 GPa/vol%, respectively. This is possibly because the well-dispersed C in the atomic scale changed the elastic bonding characteristics of the metallic bonds between the Al atoms.

Highlights

The development of lightweight energy-efficient materials with high-level performance is a major concern in several industrial fields for compliance with the increasingly demanding global environment regulation trends while maintaining production
The last group includes the specimen heat-treated at 650 °C, which undergoes a reduction in the elastic modulus, where the formation of carbide A l4C3 phases becomes dominant and most fullerenes seem to disappear, as observed through the X-ray diffraction (XRD), Raman, and X-ray photoelectron spectroscopy (XPS) analyses
The contribution of each phase to the elastic and plastic behaviors of the composites was examined through the scanning acoustic microscopy (SAM) technique and hardness measurements

Summary

Introduction

The development of lightweight energy-efficient materials with high-level performance is a major concern in several industrial fields for compliance with the increasingly demanding global environment regulation trends while maintaining production. Aluminum is the most abundant metal on earth, and it is the fourth most electrically/thermally conductive and the second lightest metal (2.7 g/cm[3] in density) among metallic structure materials[1,2,3] It has significant uses in structural and functional components in the automotive, biomedical, and electronic industries. Carbon that was thermally decomposed from individually dispersed fullerenes was intercalated into the Al interstitial sties to form Al-C phases after annealing, rather than aluminum carbides[20]. This may happen under the special circumstance where the thermal energy for chemical decomposition of fullerenes is sufficiently lower than that for carbide formation because of the small radius of fullerenes. A systematic study has not been conducted on the role of fullerene, aluminum carbides, or these unknown Al-C phases on the elastic and plastic behaviors of Al-based materials

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