Mechanical Behavior of Ultrafine-Grained Ni-Carbon Nanotube Composite

Ultrafine-grained (UFG) Ni and multi-walled carbon nanotube (CNT) composite powders were prepared using non-covalent functionalization of CNTs to promote cohesion between the metal powders and CNTs. Following consolidation using spark plasma sintering, the resultant Ni-CNT composites had densities \u3e97 % with well-dispersed CNT reinforcements. Tensile testing revealed comparable fracture strengths between the reinforced and unreinforced UFG Ni, whereas the former exhibited smaller fracture strain than the latter. In addition, the former had higher micro-hardness than the latter. The results are rationalized using a shear-lag model, and it is suggested that grain edge lengths should be used as the reinforcement lengths when applying the model to tensile stress response descriptions