NONEQUILIBRIUM CRYSTALLIZATION OF EXPLOSIVE AND NON- EXPLOSIVE TYPE

10.25712/ASTU.1811-1416.2026.02.009

Abstract

The paper presents a comparative analysis of the kinetics of crystallization of pure components of tin (Sn), bismuth (Bi), and a eutectic alloy of the Sn-Bi system under conditions of quasi-equilibrium and nonequilibrium crystallization. The relevance of the study is due to the inconsistency of literature data on the overcooling of low-melting metals and alloys, which is associated with differences in experimental methods and conditions. The effect of the superheating  temperature of the melt relative to the melting temperatures of the pure  Sn and Bi components of the eutectic alloy of the Sn-Bi system on the maximum overcooling  has been studied by cyclic thermal analysis. The existence of a critical overheating temperature  for Sn and Bi has been confirmed, with melt cooling above which crystallization proceeds according to a nonequilibrium explosive mechanism (NRVC), and below that, a quasi-equilibrium isothermal one (CRC). For Bi the value is  К , for Sn  К. It is shown that the eutectic Sn-Bi alloy crystallizes isothermically with constant limiting overcooling  К. The results obtained are interpreted from the standpoint of the cluster-coagulation theory of crystallization.