The consideration of short-range order in the melts of close-packed metals is represented on the basis of analysis of all distinguishing maxima on the radial distribution function (RDF) of atoms in the ordered region. SOBOSOSOB7>The procedure to determine structure parameters in liquid metals by diffraction study is described in Part I of our report. Here an attempt is made to find out common and distinguishing features of liquid metals having close-packed premelting structures.In a first approximation, the close-packed crystal structure of metals may be assumed as a regular packing of spherical atoms in a short-range order. The contribution of the directional interaction there is significantly less than in metals of friable structures. The denser atomic packings occur also in their melts and result in different values of the important ratios, such as S2/S1 = 1.80 -1.90; = 1.81 -1.93.Their structures in the liquid state are much closer to the parameters of the simple liquid model (DRPHS).A complete analysis of all features of the structural factors and RDFs is necessary to discover short-range order in the melts.Comparing the first maximum abscissas of liquid fee metals with their line polyciystalline diagrams, agreement with (111) reflection is found at an accuracy of 1%. The shortest interatomic distance in the crystal, r®, is close to the abscissa of the first coordination RDFs maximum. The square under the first peak is on the average near z^1" = 11. On the basis of this data it has often been confirmed that the ordering in the melt corresponds to a crystal-like model /1,2/. Nevertheless, a more detailed analysis excludes this conception. Figure 1 represents the structural factor of liquid nickel /3/. The agreement between some maxima and polycrystalline reflections cannot be considered as Fig. 1: Structural factor and difference RDF curve of liquid nickel at 1773 Κ /8/. 1 -the line diagram of polycrystalline Ni; 2 -the coordination spheres radii in fcc-Ni and the numbers of their ζ atoms.

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Interface tension and adhesion were determined in a number of binary and ternary metallic systems with immiscibility gaps. In ternary systems, compositions of equilibrium phases were preliminarily defined. Concentrations of components on phase boundaries were estimated.The interface boundary between two segregating metallic melts has not yet been investigated as fully as that between liquid metals and liquid salts or oxides. Nevertheless, interface characteristics such as interface tension ση, adhesion Wa, compositions of surface layers xf, are not only of scientific interest. They are necessary for the analysis of emulsification processes of melts, for the definition of phase adhesion in the production of composition materials and in other processes.In this report, these properties are considered in a number of binary and temaiy metallic systems. The investigations were carried out in the laboratory of the chair of "Theory of Metallurgical Processes" at the Urals State Technical University. METHODSOne of the most suitable methods of definition of interface tension ση at a phase boundary of immiscible metallic melts is calculation of its value by using magnitudes of the surface tensions σχ and σι of mutually saturated phases and the contact angle α (Fig. 1). For this purpose a drop of one liquid alloy is placed in a cup, and the other melt is placed in a surrounding circular groove /!/. Fig. 1: Substrate (3) for equilibrium contact angle (a) of two melts (1 and 2), definition and scheme of action of surface forces. Calculations were made according to the equation J/2(1)Since the magnitude of interface tension is very sensitive to impurities, metals with a total content of impurities of no more than 0.01% were used in our experiments. The experiments were usually performed at a vacuum of 10^ Pa, and for metals possessing a high affinity for oxygen, they were carried out in a protective atmosphere of purified hydrogen. A special vacuum furnace with a quenching bath was used for determination of the mutual solubility of liquid phases and for quenching of metallic emulsions. BINARY SYSTEMSSome tens of metallic pairs, demonstrating limited miscibility in the liquid state, are known. Unfortunately, 255Brought to you by | Purdue University Libraries the limits of immiscibility gaps have not been reliably established in the majority of the cases. This fact prevents studies of interface boundary properties. The experimental difficulties may be related to high chemical activity and saturated vapor pressure of one of the components in the experimental temperature interval.Here the interface boundary properties of Fe-Ag, Ni-Ag, Co-Ag 12,7)1, Fe-Sn /4/ ,Ga-Bi, Ga-Pb systems are discussed.In the first three systems, interface tension has been defined only at one value of temperature owing to the absence of data on the temperature dependencies of solubilities. In the rest polytherms of σ 12 were determined, too.The solubility of silver in iron is negligible and it does not exceed 0.1 mole % at 1823 K. In this limit no influenc...