Microstructural Configuration and Impact Toughness of Graphite Ductile Iron Reinforced by Trace Amount of TiC-TiB2 Nanoparticles

The present research investigated the effects of TiC-TiB2 nanoparticles on the microstructure and impact toughness of graphite ductile iron. The nanoparticle-reinforced ductile iron samples were prepared by using an aluminum master alloy containing TiC-TiB2 nanoparticles. It was found that the addition of nanoparticles refined the graphite nodules, pearlitic structure and grains. According to the edge-to-edge matching model, the nanoparticles served as nucleation sites for graphite and austenite during the liquid-solid phase transformation. Moreover, the impact toughness was improved by 50.4, 36.2 and 28.3% at the temperatures of 20, 0 and - 20 degrees C. The fracture surfaces were dominated by cleavage fracture for ductile iron without nanoparticles. After adding nanoparticles, ductile risers were found around graphite nodules, and some nanoparticles were detected within the dimples on the ductile risers.