TiC nanoparticles enhanced ultrasonic treatment for microstructure refinement of A356 alloy

Abstract In this work, the effect of TiC nanoparticles (NPs) inoculation and ultrasonic treatment (UT) on the refining behavior of A356 alloy was investigated. Compared with the base and sonicated samples, dendritic grains and eutectic Si phases were simultaneously refined with extra NPs addition. Microstructure analysis revealed that these NPs had two distribution types, i.e., intragranular distribution (within the primary α-Al grains) and extragranular distribution (inside the eutectic cells). Considering the ultrasonic cavitation effects and good crystallographic matching between TiC and Al, it is suggested that the finer and uniform grain structure can be attributed to the higher nucleation density facilitated by the activated TiC NPs during solidification. Meanwhile, the enriched NP-induced growth restriction mechanisms are proposed to explain the further refinement and modification in eutectic Si.