Modern ideas about the micronhomogeneous structure of metal melts (overview)

Abstract

The review examines the question of modern ideas about the structure of metal melts in a wide temperature-concentration interval. The existing theories and models of their micro-inhomogeneous structure, namely quasi-chemical, cluster, and colloid, are presented. The quasi-chemical theory takes into account the arrangement of atoms in a metallic liquid, i.e., it is believed that the probability of atoms of the 1st and 2nd grade in one of the two neighboring places is different. It is based on comparing the probabilities of different ways of filling neighboring places. A cluster is a microgrouping of atoms that preserve a certain close-range order in their mutual arrangement and which are united by a general oscillatory movement of the entire grouping and at the same time half connected at any moment with the entire mass of matter in a given volume. Elements of disorder in this model of metal melts are introduced by the movement of activated atoms, thermal fluctuations, and diffusion displacements of clusters, which are associated with the movement of clusters, periodic formations and closing of intercluster gaps, and relaxation displacements of atoms in the middle of clusters, which are associated with thermal fluctuations. The colloidal model was formulated to explain the micro-heterogeneity of eutectic systems. According to this theory, the microheterogeneity observed after melting the sample is due to the long-term existence of microregions in the melt, which are a legacy of the chemically inhomogeneous initial casting, which is enriched with various components. These regions are considered as dispersed particles and the melt is considered as a microheterogeneous system consisting of dispersed and dispersed phases. The microheterogeneous state of the melt was distinguished by the presence of an interfacial surface that separates the inclusion from the main melt. The work also presents results that confirm the fact that amorphous alloys are structurally microinhomogeneous. Since these systems are formed at cooling rates of the initial melt of about 106 0C/s, their micro-heterogeneity is associated with the structure of liquid metal solutions. Keywords: micro-heterogeneity, metal melt, models, amorphous alloys.