Microstructure and properties of nano-C and in-situ Al₂O₃ reinforced aluminum matrix composites processed by high-pressure torsion

ABSTRACT

In this study, Al-Si matrix composites reinforced with In situ Al₂O₃, C nanotubes (CNTs), and graphene nanoplatelets (GNPs) were prepared by ball milling, hot-isostatic pressing (HIP), and subsequent high-pressure torsion (HPT). Microstructures, interfacial bonding, and electrical and mechanical properties of the composites were analysed. In situ Al₂O₃ particles and whiskers were formed via reaction between Al powder and SiO₂ powder. Grains of the composites were significantly refined and reinforcements were well dispersed in the matrix by HPT. A sub-micron equiaxed grain structure with an average grain size of 0.60 μm was obtained. Interface between the CNTs and the matrix was narrow and had no brittle phase. With an increase in the number of HPT cycles, microhardness and electrical conductivity of the composites increased. Strengthening mechanism of the Al matrix composites was mainly fine-grain strengthening. Dislocation accumulation and grain boundary evolution caused by HPT were examined.

Graphical abstract

KEYWORDS:

• Al-Si matrix composites
• interface
• high-pressure torsion
• electrical property
• mechanical property
• strengthening mechanism

Acknowledgments

This work was supported by the Key Laboratory of Infrared Imaging Materials and Detectors, Shanghai Institute of Technical Physics, Chinese Academy of Sciences (No. IIMDKFJJ-19-08), R&D Projects Funding from the Research Council of Norway (No. 263875/H30), and the China Postdoctoral Science Foundation (Nos. 2015M570794 and 2018T110993).

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No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

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Funding

This work was supported by the Chinese Academy of Sciences [No. IIMDKFJJ-19-08]; the Research Council of Norway [No. 263875/H30]; the China Postdoctoral Science Foundation [Nos. 2015M570794 and 2018T110993].