Processing and Properties of CNTs/ADC12 Nanocomposite

Carbon nanotubes (CNTs)-reinforced ADC12 nanocomposite was successfully fabricated via casting. The CNTs-Al master alloy was prepared by hot extrusion, and the CNTs were dispersed into the matrix by a high-intensity ultrasonic treatment during the casting process to yield 0.5, 1.0, 1.5 wt.% of the CNTs/ADC12 composite. The key step in arriving at homogeneous distribution of CNTs was preparation of the CNTs-Al master alloy and the introduction of a high-intensity ultrasonic treatment method. The cavitation bubbles that adhered to the aggregated CNTs closed rapidly and released large amounts of energy, which had an impact via the cavitation effect, which made the aggregated CNTs dissociate and disperse homogeneously into the melt. Under the conditions of ultrasonic power of 2.1 kW and ultrasonic time of 10 min, the mean diameter of α-Al was 53.2 μm, which was 58.9% lower than that of the matrix. The microhardness and the ultimate tensile strength (UTS) of nanocomposite with 1.0 wt.% CNTs addition increased by 29.3 and 27%, respectively, as compared with the matrix. CNTs can be dispersed in the matrix homogeneously. It was observed by scanning electron microscope (SEM) that CNTs as a load-bearing element were embedded in the matrix independently, enhancing the mechanical properties. This suggested that the improvement of mechanical properties could be attributed to the size and degree of CNTs clustering, the load transfer from the matrix to the CNTs and the grain refinement of the nanocomposite.