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Solvent-free nanofluid displays liquid-like function in the absence of solvent at room temperature by grafting organic salts on the surface of materials. In this study, carbon nanotube (CNT) fluid is synthesized by a chemical grafting method for the preparation of CNTs/copper (Cu) composite powder. After hot-pressing and sintering, the CNTs-fluid/Cu composites are further treated by hot rolling to improve their mechanical properties. The microstructure and mechanical properties of the as-obtained composites are systematically characterized by SEM, TEM, FTIR, Raman, rheological analysis, hardness and tensile tests. It is demonstrated that the optimal mechanical properties of the composite can be achieved by adding 0.75[Formula: see text]wt.% CNTs nanofluid. The yield and tensile strength of the resultant material are about 397.6[Formula: see text]MPa and 517.5[Formula: see text]MPa, respectively, which are 282% and 156% higher than that of pure Cu. Meanwhile, its hardness value reaches 152.2[Formula: see text]HV, which is increased by 27% and 38% of pure Cu and the unrolled sample, respectively. Such significant property improvement is conjointly contributed by load transfer strengthening, Orowan strengthening, matrix strengthening and thermal mismatch. This study provides a new insight into the interface structure to enhance the mechanical properties of metal matrix composites.

Silica/Cu composites generally fail to achieve the high strength due to the weak interfacial bonding between SiO2 and Cu. In the current work, the first use of silica quantum dots (SiO2 QDs) as a copper-based composite reinforcement. Silicon quantum dots (Si QDs) and copper acetate are employed as raw materials for spray pyrolysis to obtain an interconnected structure of SiO2 QDs/Cu2O, which achieve well-dispersion of the reinforcement and good interface combination in one step. The SiO2 QDs/Cu2O composite block is obtained by ball milling, hydrogen reduction, and SPS sintering. Micro interface structure and strengthening mechanism of the composites are investigated and presented in detail. Microstructural analysis discovers the Cu2O transition layer between SiO2 QDs and Cu matrix and well-dispersed SiO2 QDs in the Cu matrix. The good bonding of grain interface can significantly enhance the mechanical properties. The 1.2 wt% SiO2 QDs/Cu composite block exhibits an excellent ultimate tensile strength of 456.63 MPa, which is 101.68% higher than that of unreinforced Cu (227.39 MPa). Furthermore, the composite block maintains the high conductivity (83.27% IACS) and elongation (8.86%). Moreover, this work can promote the development of Cu matrix composites using ceramic reinforcement with an improved interface bonding.