Microstructure Refinement and Strengthening-Toughening Mechanisms of Gray Cast Irons Reinforced by In Situ Nanosized TiB2-TiC/Al Master Alloy

Herein, the effects of addition of TiB2-TiC nanoparticles on the microstructure and tensile properties of as-cast gray cast irons are investigated. The in situ nanosized TiB2-TiC/Al master alloy is added in the casting process. It is found that the presence of TiB2-TiC nanoparticles refines the graphite flakes and pearlite and increases the yield strength, tensile strength, and fracture strain simultaneously. The strengthening mechanisms are related to grain refining strengthening and Orowan strengthening. The toughening mechanism is related to the scattering behavior of cracks by nanoparticles.