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In the present work, the microstructure, phase constitution, and corrosion behavior of binary Sn–xZn alloys (x = 5, 9 and 15 wt.%) were investigated. The alloys were prepared by induction melting of Sn and Zn lumps in argon. After melting, the alloys were solidified to form cast cylinders. The Sn–9Zn alloy had a eutectic microstructure. The Sn–5Zn and Sn–15Zn alloys were composed of dendritic (Sn) or (Zn) and eutectic. The corrosion behavior of the Sn–Zn alloys was studied in aqueous HCl (1 wt.%) and NaCl (3.5 wt.%) solutions at room temperature. Corrosion potentials and corrosion rates in HCl were significantly higher compared to NaCl. The corrosion of the binary Sn–Zn alloys was found to take place by a galvanic mechanism. The chemical composition of the corrosion products formed on the Sn–Zn alloys changed with the Zn weight fraction. Alloys with a higher concentration of Zn (Sn–9Zn, Sn–15Zn) formed corrosion products rich in Zn. The Zn-rich corrosion products were prone to spallation. The corrosion rate in the HCl solution decreased with decreasing weight fraction of Zn. The Sn–5Zn alloy had the lowest corrosion rate. The corrosion resistance in HCl could be considerably improved by reducing the proportion of zinc in Sn–Zn alloys. [ABSTRACT FROM AUTHOR]

In this study, Sn-Zn solder samples containing 2 to 12 wt.% Zn were fabricated and reflowed into a Cu substrate. The microstructure of solder samples was observed after reflow and aging for up to 1000 h at 150°C. Thermodynamically stable intermetallics (IMCs) Cu-Zn and Cu-Sn formed at the interface depending on the solder composition. Formation of different interfacial IMCs during soldering and after prolonged aging is explained by the spalling mechanism that resulted from the depletion of Zn from the solder matrix. [ABSTRACT FROM AUTHOR]

Wetting of Al and Ni substrate by Sn-Zn eutectic-based alloys with 0.5 (wt.%) of Ga and 0.2 (wt.%) of Na was studied using the sessile drop method in the presence of ALU33 flux. Spreading tests were performed for 60 s, 180 s, and 480 s of contact, at temperatures of 503 K, 523 K and 553 K (230°C, 250°C, and 280°C). After cleaning the flux residue from solidified samples, the spreading areas of Sn-Zn0.5Ga and Sn-Zn0.2Na on Al and Ni substrate were determined. Selected, solidified solder-pad couples were cross-sectioned and subjected to scanning electron microscopy with energy dispersive spectroscopy, x-ray diffraction study and synchrotron measurements of the interfacial microstructure and identification of the phases. The growth of the intermetallic NiZn phase layer was studied at the solder/Ni substrate interface, and the kinetics of the formation and growth of the intermetallic layer were determined. The formation of interlayers was not observed on the Al pads. On the contrary, dissolution of the Al substrate and migration of Al-rich particles into the bulk of the solder were observed. [ABSTRACT FROM AUTHOR]

In this work, data for liquid SnZn alloys with Ag, Bi, Ga and Na additions are presented. Thermophysical properties, viscosity, density and surface tension were measured using the discharge crucible method (DC). In previous studies, Na content added to Sn-Zn caused increased density and viscosity, and decreased surface tension. Ga content generally reduced physicochemical properties in comparison to eutectic Sn-Zn alloy. The measurements were performed over a temperature range of 523–823 K. The results show that the Ag and Bi additions to Sn8.9Zn (wt%) cause increased density. The different character of changes for surface tension and viscosity, was observed, for Ag content increasing in contrast to Bi which caused reducing both properties in comparison to eutectic SnZn alloy. Similar character of changes for Sn-Zn3.5Ag and Sn-Zn3.0Bi alloys with Ga and Na additions as for Sn-ZnGa and Sn-ZnNa alloys, was observed. [ABSTRACT FROM AUTHOR]

Highlights: [•] Small amounts of Ni and Sb have been added into hypoeutectic Sn–6.5Zn solder. [•] Sb addition refined the microstructure and Ni enhanced the formation of (Ni, Zn)3Sn4. [•] Ni and Sb can slightly reduce the undercooling and pasty range. [•] The Sn–6.5Zn–0.5Sb alloy has the highest UTS and appropriate ductility. [•] Correlations between the microstructure and mechanical parameters were analyzed. [Copyright &y& Elsevier]

Abstract: The process of tin–zinc alloy electrodeposition from aqueous citrate electrolytes was studied. The influence of applied potential, current density, hydrodynamic conditions, electrolyte composition and charge transfer on the electrodeposition of Sn–Zn alloy was determined. Depending on these parameters, coatings with different compositions and appearances can be obtained. The surface composition of deposits was ascertained by chemical analysis (WDXRF). The morphology of coatings was studied by SEM. The electrodeposition of bright, shiny Sn–Zn coatings on steel is possible from the citrate baths studied. The presence of zinc ions in the electrolyte results in a significant inhibition of tin reduction rate, which enables the electrodeposition of tin–zinc alloy layers containing from about 0.5 to 75wt.% of Zn, with high current efficiency, within the range from 80% to almost 100%. Two phases are formed in deposits: a hexagonal zinc phase and a tetragonal β-tin phase. [Copyright &y& Elsevier]

Highlights: [•] Same amount of Ni and Sb have been added into Sn–6.5Zn solder. [•] Correlations between the microstructure and creep parameters were analyzed. [•] Ni and Sb are slightly reduced the undercooling and pasty range. [•] Sb and Ni provide about 270% and 182% higher creep resistance than Sn–6.5Zn solder. [ABSTRACT FROM AUTHOR]

Abstract: Creep behavior of the hypoeutectic Sn–Zn alloys containing 2.5–6.5wt.%Zn was studied by impression testing and compared to that of the eutectic Sn–9Zn alloy. The tests were carried out under constant punching stress in the range 50–110MPa and at temperatures in the range 298–370K. Assuming a power law relationship between the impression rate and stress, average stress exponents of 6.2, 6.4, 7.3, and 7.4 and activation energies of 41.9, 43.9, 44.5 and 46.0kJmol−1 were obtained for Sn–2.5Zn, Sn–4.5Zn, Sn–6.5Zn and Sn–9Zn, respectively. These activation energies are close to 46kJmol−1 for dislocation climb, assisted by vacancy diffusion through dislocation core in the Sn. This, together with the stress exponents of about 7 suggests that the operative creep mechanism is dislocation climb controlled by dislocation pipe diffusion. Analysis of the data showed that for all loads and temperatures, the eutectic Sn–9Zn had the lowest creep rates and thus the highest creep resistance among all materials tested. The creep resistance of Sn–6.5Zn was only slightly lower than that of the eutectic alloy while the other two alloys showed much lower creep resistances. This is attributed to the higher volume fraction of Zn-rich second phase precipitates in the more concentrated alloys which acts as the main strengthening agent in the Sn–Zn alloy system. [Copyright &y& Elsevier]

Abstract: The thermo-electrical properties of Sn–Zn alloys have been investigated for four different compositions. The SEM micrographs and EDX analysis of the samples have been obtained. The electrical resistivity measurements were performed by using four-point probe technique in the temperature range 300 K–575 K. The resistivity of samples increases linearly with temperature and the electrical conductivity is inversely proportional to temperature. The electrical current preferentially flows through the pure Sn phase having lower resistivity in the matrix. Also, thermal conductivity of samples has been measured by using the radial heat flow method. It has been found that the thermal conductivity decreases with the increasing temperature and composition of Sn. The results were consistent with available experimental results of other studies. Finally, the temperature coefficient of electrical resistivity and the temperature coefficient of thermal conductivity have been determined, which were independent from the composition of Sn and Zn. [Copyright &y& Elsevier]

Abstract: Hypoeutectic Sn–Zn may be a better choice than the eutectic Sn–9Zn as a lead-free solder. We checked the non-equilibrium melting behaviors of a series of Sn–Zn alloys (2.5–9 wt.% Zn) by differential thermal analysis, and found that at a heating rate of 5 °C/min, Sn–6.5Zn behaves the same way as the eutectic Sn–9Zn in melting. Dipping and spreading tests were carried out to characterize the wettability of Sn–Zn alloys on Cu. Both tests indicated that Sn–6.5Zn has significantly better wettability to Cu than Sn–9Zn does. The reaction layers formed during the spreading tests were examined. For all samples with 2.5–9 wt.% Zn, two reaction layers are formed at the interface, a thick and flat Cu5Zn8 layer adjacent to Cu and a thin and irregular Cu–Zn–Sn layer adjacent to the alloy. The total thickness of the reaction layers between the alloy and Cu was found to remarkably decrease with decrease of the Zn concentration. [Copyright &y& Elsevier]

• The thermal conductivities of Sn–x at% Zn (x = 69.5, 48.3, 28.1 and 14.1) alloys were determined. • Composition and temperature dependences of the thermal conductivity were obtained. • Phase transition temperatures and related heat effects were measured using DSC. • The microstructures of the Sn–Zn alloys were determined. Four hypereutectic Sn-Zn alloys with 69.5, 48.3, 28.1 and 14.1 at% of Zn were produced by mixing and melting of pure metals Sn and Zn followed by cooling in air to room temperature. Microstructure and chemical compositions of prepared samples were analyzed by using scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS). It was found that morphology of primary (Zn) phase changes from rounded and equiaxed dendritic structure to plate-like grains and finally to needle-like shape of grains with decreasing Zn content. Formation of characteristic broken-lamellar type of eutectic microstructure was observed in all investigated alloys. Melting behavior of the alloys was studied using differential scanning calorimetry (DSC). Phase transition temperatures and corresponding heat effects were experimentally determined and compared with the results of thermodynamic and phase equilibria calculations using the CALPHAD (CALculation of PHAse Diagrams) method and optimized thermodynamic parameters from literature. Thermal diffusivity of the studied alloys was measured using xenon flash method in the temperature range from 25 to 150 °C. Based on the measured values of thermal diffusivity and calculated specific heat capacity data, thermal conductivities of the solid alloys were obtained. It was found that thermal conductivity decreases monotonously with increasing temperature and Sn content. The results of thermal conductivity measurements were compared with literature data and with the data obtained from the Wiedemann-Franz law and measured electrical conductivities. [Display omitted] [ABSTRACT FROM AUTHOR]