The effects of Al-Ti-C and La on the fluidity of a ZL205A alloy after separate and combined addition were studied by conducting a fluidity test. The fluidity of the ZL205A alloy first increased and then decreased with the increasing addition of Al-Ti-C and La; it peaked at 0.3% and 0.1% for Al-Ti-C and La, respectively. The combined addition of Al-Ti-C and La led to better fluidity, which increased by 74% compared with the base alloy. The affecting mechanism was clarified through microstructure characterization and a DSC test. The heterogeneous nucleation aided by Al-Ti-C and La, the number of particles in the melt, and the evolution of the solidification range all played a role. Based on the evolution of the fluidity and grain size, the optimal levels of Al-Ti-C and La leading to both high fluidity and small grain size were identified.
Keywords: Al–Ti–C; La; ZL205A; fluidity; grain refinement.