Microstructure and mechanical properties of consolidated Cu-Cr-CNT nanocomposite prepared via powder metallurgy

Highlights: • Cu-Cr/CNT nano-composite were produced by mechanical alloying and hot pressing. • Pressing temperature has a significant on improvement of hardness by about 65%. • Effects of CNTs on consolidation behavior and properties were investigated. • CNTs make density, hardness, shear strength and elongation to failure decrease. • Presence of CNTs led to higher wear resistance and thermal stability. In this paper, Cu-1wt.%Cr and Cu-1wt.%Cr/5wt.%CNT nanocomposite powders were produced by mechanical alloying method. Then, nanocomposite samples were consolidated by hot pressing at different temperatures of 25, 300 and 500 °C, times of 30, 60, 90 and 120 s and pressures of 40, 80 and 120 MPa. The consolidated nanocomposite samples were characterized by X-ray diffraction, scanning electron microscopy, shear punch test, wear test and measurements of density, microhardness and thermal stability. It was found that pressing temperature has a significant effect on improvement of hardness by about 65%. A quantitative relationship between relative density and pressing pressure was proposed. The effects of CNTs addition on the consolidation behavior and characteristics of the consolidated samples were also investigated. The results showed that the addition of CNTs makes the relative density, hardness, shear strength and elongation to failure decrease. However, in the presence of CNTs, the friction coefficient decreased by 82%; therefore, the wear resistance of the Cu-1wt.%Cr/5wt.%CNT nanocomposite was 72% higher than that of the Cu-1wt.%Cr. Additionally, presence of 5wt.% CNTs led to a four times greater thermal stability.