Synergistic strengthening effect of carbon nanotubes (CNTs) and titanium diboride (TiB2) microparticles on mechanical properties of copper matrix composites

Synergistic strengthening is increasingly explored for developing high-performance metal matrix composites. In the present work, copper matrix composites reinforced with carbon nanotubes (CNTs) and TiB2 microparticles were fabricated via electroless deposition, powder metallurgy, hot extrusion, and water quenching. The synergistic strengthening effect of the nano-and micro-reinforcements was elaborated and analyzed based on experimental investigation and theoretical calculation. (1CNT-4TiB2)/Cu composite exhibited a better combination of the tensile strength of 375MPa with elongation of 32.4% than other composites, representing 86.3%, 71.5%, and 22.8% strength increment in comparison with pure Cu, 4TiB2/Cu composite, and 1CNT/Cu composite, respectively. The strengthening efficiency of CNTs in (1CNT-4TiB2)/Cu composite is markedly higher than that in 1CNT/Cu composite (126.7 and 82.3, respectively), confirming the synergistic strengthening effect in enhancing the mechanical properties. Quantitative analysis and experimental characterization indicated that the thermal mismatch and load transfer mechanism of CNTs were the main factors contributing to the tensile strength enhancement of the composite. The synergistic strengthening effect was attributed to that TiB2 microparticles improved the homogeneous dispersion of CNTs, promoting the proportion of thermal mismatch and load transfer mechanisms. The present work may provide a new sight into improving the synergistic strengthening effect in metal matrix composites.