Microstructure and Tensile Properties of Ductile Cast Iron Composites Reinforced by Tic Nanoparticles

Abstract

Four groups of TiC reinforced ductile cast iron (DCI) composites with different ceramic nanoparticle contents were prepared by negative pressure lost foam casting method, in which the TiC nanoparticles were added into the ingot by foamed TiC-foam preforms. Then the effect of TiC content on the microstructure and mechanical properties of DCI was investigated. The results show that the addition of TiC nanoparticles affect significantly the morphology, size and quantity of graphite spheres in the DCI, as well as the proportion, size and orientation of pearlite and ferrite in the matrix. The heterogeneous nucleation theory and binary lattice mismatch model are used to explain the effect of TiC on the microstructure of ingots. The tensile experiments show that the tensile strength of the DCI increases with increasing the addition of TiC, while the elongation first increases and then decreases. The improvement of mechanical properties of the DCI is related to the fine grain strengthening of TiC nanoparticles and its hindering effect on crack propagation.

Keywords: Ductile cast iron (DCI), TiC nanoparticles, microstructure, Tensile properties