# Production and Characterization of Cu/CNT Nanocomposites
###### Abstract  
In this research, copper nanocomposites reinforced with carbon nanotubes (CNTs) were produced by ultrasonication and conventional sintering, followed by cold rolling. These nanocomposites may be good candidates due to their excellent properties for components in the electrical, electronics, or aerospace industries with highly demanding requirements. The main objectives of this work were to produce and characterize the Cu/CNT nanocomposites, identify the strengthening mechanisms, and study the deformation behavior of the nanocomposites during cold rolling. The nanocomposites exhibited an improvement in hardness and tensile strength of 17 and 67%, respectively, attesting to the strengthening effect of the reinforced material. The yield strength of the nanocomposites was determined considering different mechanisms: (1) load transfer, (2) grain refinement or texture, (3) dislocation, and (4) Orowan strengthening mechanisms. The microstructural and calculated results show that the mechanism that contributes the most to the increase in the properties of the nanocomposite is the load transfer. The nanocomposites show a different texture evolution of the Cu matrix during cold rolling. This can be due to differences in the active slip planes between the matrix and the nanocomposite, which affects the lattice rotation. deformation behavior; cold rolling; metal matrix nanocomposites; carbon nanotubes; texture evolution +
Footnote †: journal: Applied sciences  
for manufacturing these nanocomposites [10; 11; 12]. The powder metallurgy process can be subdivided into four key steps, starting with the powder mixing and dispersion with the metal powder and reinforcement, followed by the pressing and the sintering of the samples [13]. In recent years, there has been an increase in published papers on Cu/CNT nanocomposites [4; 5; 6; 7; 8; 14; 15; 16; 17; 18]. However, producing these nanocomposites by this process is still less reported than the Al/CNT and Ni/CNT nanocomposites, even though identifying strengthening mechanisms has been a topic of these works. Identifying and understanding the strengthening mechanisms is crucial for optimizing and implementing MMNCs. For Cu/CNT nanocomposites, although the load transfer mechanism is the most reported, grain refinement or texture, Orowan, and dislocation strengthening mechanisms are also observed to contribute to the increased yield strength of the nanocomposites. For instance, [PERSON] et al. [14] reported on the grain refinement strengthening in Cu/CNT nanocomposites processed by high-pressure torsion. The grain size was evaluated by electron backscatter diffraction (EBSD), and the presence of CNTs promotes a reduction from approximately 517 nm (Cu matrix) to 180 nm (nanocomposite) in the average grain size. This can be explained due to the presence of CNTs at grain boundaries that act as inhibitors of grain boundary movement. Moreover, the CNTs significantly affected the dislocation motion, promoting a dislocation density increase during the deformation of the nanocomposites. The results of tensile tests and analyses of the fracture surface showed an improvement in the mechanical properties of the nanocomposites and the presence of individual CNTs embedded in the matrix. [PERSON] et al. [7] investigated the mechanical properties of Cu/CNT nanocomposites produced by electrodeposition. The authors observed an improvement in the tensile strength and ductility of the nanocomposites. The strengthening mechanisms identified were the load transfer and the dislocation hardening due to the increased dislocation density observed for the nanocomposites. [PERSON] et al. [17] applied mathematical calculations to investigate the strengthening mechanisms of Cu/CNT nanocomposites produced by SPS. The results showed that load transfer was the mechanism that most contributed to strengthening the nanocomposite, followed by increased dislocation density and grain refinement. [PERSON] et al.