Peri-eutectic transition during crystallization of undercooled ternary alloy melt



Peri-eutectic transition was investigated in terms of the dependence of crystallization behavior on undercooling in Cu–Ag–Ge ternary alloy composed of (Ag), ζ(Cu5Ge), and ε2(Cu3Ge) phases. (Ag + ε2) pseudobinary eutectic is the product of both peri-eutectic and subsequent pseudobinary eutectic transitions. Nanoscale structure of anomalous (Ag + ε2) pseudobinary eutectic forms at the maximum undercooling, which is ascribed to the independent nucleation and growth from the liquid. The decrease of (Ag + ε2) pseudobinary eutectic at a high undercooling is due to that the phase transition happening at the beginning solidification stage proceeds more thoroughly at a higher undercooling.