ON THE THEORY OF SUPERCOOLED LIQUID SOLID IFICATION .2. KINETICS OF CLUSTER FORMATION AND COMPETITIVE NUCLEATION

The kinetic theory of the non-crystalline embryo formation is develope d. The multiplicity and partially broken ergodicity of the cluster str ucture states is taken into account. The metric of the set of cluster structure states is introduced which defines the cluster structure sta te space. The set of the structure states of a cluster with a fixed nu mber of atoms forms an ultrametric subspace, and therefore the cluster state space is an assembly of the ultrametric subspaces. The kinetics of the cluster structure transformations is described by the diffusio n equation (it is the generalized Zeldovich equation) in the cluster s tructure state space. The nucleation rate of clusters is obtained and the kinetic vitrification temperature is defined. As an example, the c ompetitive nucleation of crystals and clusters in a metallic melt is c onsidered.