Key Takeaways & Executive Findings
- •• Incorporating nanotwins (3–30 nm width) into Cu/CNTs composites via cryogenic rolling and optimized powder particle size significantly enhances strength–ductility synergy. • Nanotwin strengthening contributes 19.9% of the total strength increment, alongside grain refinement and dislocation strengthening. • The improved ductility is attributed to enhanced dislocation accommodation and reduced dislocation proliferation due to nanotwins. • This work demonstrates the feasibility of combining nanotwins with ex-situ reinforcements to overcome the strength–ductility trade-off in metal matrix composites.
Abstract
To exploit the combined strengthening effects of nanotwins and carbon nanotubes (CNTs) in Cu matrix composites, the nanotwins with a width ranging from 3 to 30 nm were incorporated into the CNTs-reinforced Cu matrix composites using cryogenic rolling and optimizing the initial particle size of the raw Cu powders. The formation of nanotwins in the Cu matrix composite reinforced by only 0.2 wt.% CNTs is accompanied by the increased dislocation density and refined Cu grain size, resulting in much better strength−ductility synergy than the referenced composite without significant nanotwins formation. The analysis of strengthening and toughening mechanisms demonstrates that the strength increment mainly derives from grain refinement strengthening, dislocation strengthening, and nanotwin strengthening. The strength increment from the contribution of the nanotwins accounts for 19.9% of the overall strength increment for the composite. Meanwhile, the retention of good tensile ductility can be reasonably explained by the increased dislocation accommodation ability due to the formed nanotwins and the decreased induced dislocation proliferation.
1. Introduction
Due to their remarkable mechanical properties and excellent thermoelectric properties, carbon nanotubes (CNTs) reinforced Cu matrix composites have been regarded as a new generation of Cu matrix composites for vast industrial areas [1−4]. Achieving good dispersion of CNTs and a high bonding interface with Cu matrix are the two premises for fully exploiting the potential strengthening effects of CNTs for Cu matrix composites [5,6]. To date, many fruitful methods have been developed to improve the CNTs dispersion in the Cu matrix and to strengthen the Cu−CNTs interfacial bonding. However, the overall strength of CNTs/Cu composites is still far from the expectation, because the improvement of higher strength of Cu matrix has been ignored by most researchers. Grain refinement strengthening [7], solid solution strengthening [8], and precipitation strengthening [9] have been demonstrated to be effective approaches to improve the strength of Cu matrix materials, while the improved strength is generally accompanied by reduced ductility [10].
To alleviate the contradiction between the strength and ductility of metal materials, a series of microstructure regulation methods have been proposed in the past two decades, such as incorporating the nanotwins by various approaches [11,12]. The findings show that twinning can synergistically increase the strength and toughness of Cu matrix materials, breaking the inverse relationship between the strength and toughness. For example, ZHAO et al [13] synthesized heterogeneous nanostructured Cu with a high density of nanotwins, showing a much higher strength and fracture toughness. However, almost all previous studies only focused on the effects of nanotwins on the mechanical properties of pure Cu, Cu alloy, and other metal materials, whereas the combined effects of nanotwins and ex-situ reinforcement for Cu matrix composites have not been explored yet.
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Wei-lin YU, Si-wei LUO, Juan ZHU, Min SONG, Tian-yu SUN, Jian-hong YI, Liang LIU, Yang-zhen LIU, Zhi-guo ZHANG, Yong YANG, Zhen-tao YU, Wei LI, Bai-song GUO (2025). Improving mechanical properties of Cu/CNTs composites by incorporating nanotwins. SinoTechIntel Verified Research. https://doi.org/10.1016/S1003-6326(25)66982-2
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Frequently Asked Questions
How were nanotwins incorporated into Cu/CNTs composites?
Nanotwins with widths ranging from 3 to 30 nm were incorporated into CNTs-reinforced Cu matrix composites using cryogenic rolling and optimizing the initial particle size of the raw Cu powders.
What is the contribution of nanotwin strengthening to the overall strength increment?
The strength increment from nanotwin strengthening accounts for 19.9% of the overall strength increment in the composite.
What are the main strengthening mechanisms in the Cu/CNTs composites with nanotwins?
The main strengthening mechanisms are grain refinement strengthening, dislocation strengthening, and nanotwin strengthening.
How does the incorporation of nanotwins affect ductility?
The retention of good tensile ductility is explained by increased dislocation accommodation ability due to nanotwins and decreased induced dislocation proliferation.
What is the significance of this study for Cu matrix composites?
This study demonstrates that combining nanotwins with CNTs reinforcement can achieve better strength-ductility synergy, addressing the common trade-off in metal matrix composites.
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