DETERMINATION OF CONCENTRATION BOUNDARIES OF STRUCTURAL FIELDS IN METALLIC MELTS OF BINARY EUTECTIC SYSTEMS

The regularities in the formation of structural and chemical inhomogen eities are considered in the context of a quasipolycrystalline model i n relation to binary melts of eutectic systems. Three structural field s are identified in the region above the liquidus of respective phase diagrams. It is shown that in any concrete system the location of the concentration boundaries between the structural fields can be found ex perimentally from characteristic points on the curves (isotherms) corr elating some property of liquid metals with the concentration of addit ions (second components). Structural field boundaries are found experi mentally for diluted aluminum base melts of Al-Mg, Al-Cd, Al-Fe, Al-Sr Al-Bi, Al-Zn, and AI-Sb systems. Concentrations corresponding to the appearance of second-type clusters (based on added component) in dilut ed bistructural (monocluster) solutions were found not to reveal marke d correlation with the solubility of respective components in the soli d state.