Peri-eutectic solidification and complicated microstructural evolution of liquid undercooled Cu–Ag–Sb alloy

Rapid solidification of Cu46.4Ag38Sb15.6 alloy related with peri-eutectic transition was investigated in terms of microstructural evolution by means of glass fluxing and drop tube techniques. The microstructure formations of both bulk samples and alloy droplets are influenced by undercooling prior solidification, phase transition, cooling rate and volume fraction of the residual melt during different solidification stages. Two peri-eutectic transitions (L + (Cu) → (Ag) + Cu3Sb and L + Cu3Sb → (Ag) + Cu2Sb) are verified to be involved in the solidification of bulk samples. However, the second peri-eutectic transition is not reached in the solidification pathway of alloy droplets. The solidification product of peri-eutectic transition L + α → β + γ generates in three manners: the formation of (β + γ) eutectic by the reaction between L and α phases, the direct growth of anomalous (α + β + γ) structure or (β + γ) eutectic from the melt.