Fractal Characteristics And Electrical Transport Properties Of Molten Alloys

In this paper, based on the multirange fractal model of structure of the metallic melts,relation between fractal dimension and structure, the mechanism of the fractal characteristicswere discussed. Radial distribution functions were analysed by utilizing rescaled rangeanalysis method and the distribution characteristics of the number of atoms was discussed.Electrical resistivity temperature characteristics of metallic melts during three cycles ofheating and cooling processes as well as the microscopic mechanism of the anomalous changeof resistivity were discussed.Multirange fractal analysis based on results of high temperature X-ray diffractionexperiment was used to study the temporal-spatial properties of clusters in InSn and InCumelts. The results show that partially-overlapping multirange fractal structure is observed inIn、Sn、In-40wt.%Sn、In-1wt.%Cu and In-20wt.%Cu melt and low-dimensional fractaldimension of melts increased as the temperature increases. Relation between fractaldimension and structure was discussed. Changes of fractal dimension were caused byarrangement of particles in clusters. Temperature affects the aggregation process, the higherthe temperature the greater the kinetic energy of particle’s thermal motion, thus, the structurebecomes more dense, making the increase in fractal dimension.Multirange fractal model was proposed to calculate number of atoms in transition regionof multirange fractals of In、Sn、In-40wt.%Sn、In-1wt.%Cu and In-20wt.%Cu melts. Theresults show that values of simulation show good agreement with experimental values. Fromthe analysis, the range of the transition region between two fractal regions is speculated to berelated with structure properties of metal melts. Moreover, from experimental data of pairdistribution functions, we calculated the pair correlation entropy of short range order andfound that pair correlation entropy and fractal dimension meet strict linear relation. Both areclosely related to the arrangement of the clusters, as the temperature rises, arrangement andconfiguration become more confusion, and thus pair correlation entropy and fractal dimensionincrease.Hurst’s exponent of radial distribution functions within short-range scope of In, Sn andIn-40wt.%Sn melt were determined by the rescaled range analysis method. Hurst’s exponents(H) are between0.94and0.97, which display long-range dependence. Withinshort-range scope, the number of particles that from a reference particle belongs to fractionalBrownian motion. H of radial distribution functions within short-range scope is bigger, whichshows that the number of atoms found from the reference atom are strong persistence, and thelaw of number of atoms was fractional Brownian motion.The electrical resistivity of In-xwt.%Sn(x=0,20,40,49.1,60,80,100) melts during threecycles of consecutive heating and cooling processes was measured by DC four-electrodemethod. The ρ-T curves during three cycles of heating and cooling processes meet linearrelation, abnormal changes occur in individual temperature range. For high-temperatureregion, the anomalies of ρ-T curves attributed to the melt’s metastable inhomogenousphenomenon. Anomalies deviate from linear relation near the liquidus attributed to the melt’sconcentration fluctuations. The reasons for the electrical resistivity’s negative deviation fromthe linear relationship of InSn melts were discussed. As the temperature decreases, InSnclusters gradually increase, but the clusters become more orderly, the interaction energyreduces, the probability of electron scattering reduces. In competition with the decline of thenumber of electrons, the clusters’ order is dominant, so the electrical resistivity is relativelylow, resulting in ρ-T curves’ negative deviation.Electrical resistivity-composition relation of In-xwt.%Sn(x=0,20,40,49.1,60,80,100)melts was discussed. Under isothermal conditions, electrical resistivity of the In-80wt%Snalloy melt is the highest, electrical resistivity of pure In melt the lowest. Nordheim coefficientof InSn system at different temperatures was calculated, Nordheim coefficient increased withthe increase of temperature, Nordheim coefficient-temperature curve shows almost linearrealtion.