Sn-Zn Alloys Research Articles

P99] Interfacial phenomena during wetting of Ni, Al, and Cu with Sn-Zn alloy with Ag, Al, Li additions

P99] Interfacial phenomena during wetting of Ni, Al, and Cu with Sn-Zn alloy with Ag, Al, Li additions

Interfacial Reactions in the Ni/Sn-xZn/Cu Sandwich Couples

The interfacial reactions in Ni/Sn-xZn/Cu sandwich couples which were reflowed at 270°C for 1 h and then aged at 160°C for 1–1000 h were investigated. When the 1000-μm-thick Sn-Zn alloy reacted with Ni and Cu in this couple, the results indicated that the (Ni, Cu)3Sn4, (Ni, Cu)5Zn21, and Ni5Zn21 phases were formed at Sn-1Zn/Ni, Sn-5Zn/Ni, and Sn-9Zn/Ni interfaces for 1 h reflowing, respectively. After 1000 h aging, each intermetallic compound (IMC) was converted to (Cu, Ni, Zn)6Sn5, (Ni, Cu, Sn)5Zn21/Ni5Zn21, and Ni5Zn21 (two layers) phases in the related couples. On the Cu side, the Cu6Sn5 phase in the Sn-1Zn/Cu interface and the Cu5Zn8 phase in the Sn-5Zn/Cu and Sn-9Zn/Cu interfaces were observed when the couple was reflowed at 270°C for 1 h. After 100 h aging, the (Cu, Ni, Zn)6Sn5, Cu5Zn8/(Cu, Zn)6Sn5, and Cu5Zn8 phases were formed at the Sn-1Zn/Cu, Sn-5Zn/Cu and Sn-9Zn/Cu interfaces. When the Sn-Zn alloy thickness was decreased to 500 μm, the (Cu, Ni, Zn)6Sn5 phase at the Sn-1Zn/Ni interface and the (Ni, Cu, Sn)5Zn21 phase at the Sn-5Zn/Ni and Sn-9Zn/Ni interfaces were observed after 1 h reflowing. When the couple was aged at 160°C for 1000 h, each IMC was converted to (Cu, Ni, Zn)6Sn5 and Cu5Zn8/(Cu, Ni, Sn)Zn/Ni5Zn21 phases at the Sn-1Zn/Ni and Sn-(5, 9)Zn/Ni interfaces. (Cu, Ni, Zn)6Sn5 and Cu5Zn8 were, respectively, formed at the Sn-1Zn/Cu and Sn-(5, 9)Zn/Cu interfaces for 1 h reflowing. After 100 h aging, the IMCs were converted to (Cu, Ni, Zn)6Sn5 and Cu5Zn8/(Cu, Zn)6Sn5 phases. This current study reveals that the IMC formation in Ni/(Sn-xZn)/Cu sandwich couples are very sensitive to the Zn concentration and thickness in Sn-xZn alloys.

Physical, Thermal, Mechanical Properties, and Microstructural Characterization of Sn-9Zn-XGa Alloys

Abstract The microstructural features, physicochemical, thermal, and mechanical properties of eutectic SnZn alloys with varying Ga contents were examined in this study. In the microstructure study using scanning electron microscope and X-ray diffraction analysis, intermetallic phases were not observed. The results indicated that the primary effect of Ga was increased mechanical properties. The physicochemical properties of liquid alloys, density, viscosity, and surface tension were measured using the free flow method. The addition of Ga to eutectic SnZn alloy generally reduced density, surface tension, viscosity, and melting point, and increased the coefficient of thermal expansion and electrical resistivity.

Understanding corrosion mechanism of Sn–Zn alloys in NaCl solution via corrosion products characterization

The corrosion products formed on Sn–Zn solder alloys were systematically studied to elucidate the corrosion mechanism of Sn–Zn alloys in chloride‐containing solution. Sn–Zn alloys were subjected to immersion and polarization treatment in a 0.5 M NaCl solution. Ex situ analysis, including surface and cross‐section, of the corrosion products was carried out by scanning electron microscopy (FE‐SEM) and energy dispersive X‐ray spectroscopy (EDX). The corrosion products presented porous microstructure formed by a fine interlinked network. An increase of zinc content resulted in more pores and cracks of the corrosion products, indicating degradation of corrosion resistance. Intriguing is the finding that a gradient of chlorine concentration from the outer layer inwards the alloys through the Zn‐rich precipitates is observed, which demonstrates the migration of chloride ions inwards the alloys. Based on the results, a corrosion mechanism was proposed and discussed that explains the observations. Particular attention was paid to the anodic dissolution of Zn‐rich precipitates.

Calphad-type assessment of the Sb–Sn–Zn ternary system

The ternary Sb–Sn–Zn phase diagram was investigated experimentally by scanning electron microscopy (SEM) and differential thermal analysis (DTA) of long-term annealed samples. The overall composition of each sample was measured by energy-dispersive X-ray spectroscopy (EDX). The experimental results, together with additional available literature data, were used to perform a CALPHAD-type thermodynamic assessment of this ternary system. Two calculated isothermal sections (250 and 350°C), an isopleth (x(Sn)=17.57%) and the Zn activity in liquid ternary Sb–Sn–Zn alloys at 550°C for the composition ratio Sn/Sb=1/3 and at 650°C for the ratio Sn/Sb=9 are presented with experimental points superimposed. The liquidus projection for the ternary Sb–Sn–Zn system is also presented. The agreement between calculated and experimental results is reasonable.

Thermodynamic Designing of Heat Treatable Mg–Zn–X (X = Sn, Y) Alloy Suitable for Semi-solid Processing

Current work outlines the thermodynamic prediction of Mg–Zn–X (X = Sn, Y) alloys amenable for both semi-solid metal (SSM) processing and age hardening treatment. Semi-solid processing capability of Mg–Zn–X (X = Sn, Y) alloy has been evaluated by measuring the metallurgical parameters such as ‘solidification interval’, ‘temperature liquid fraction sensitivity’ and ‘highest knee point’ from non-equilibrium Scheil solidification curve. According to thermodynamic prediction, binary Mg–Zn and ternary Mg–Zn–Sn alloys are suitable for heat treatment; however, wide solidification intervals in these systems restrict their SSM processing ability. Formation of binary Zn2Y and ternary W-Mg3Zn2Y3 intermetallic phases in Mg–Zn–Y alloy has been predicted to improve their SSM processing potential and at the same time Mg–Zn–Y alloy is found to be suitable for heat treatment process.

The effects of Na addition on the density, surface tension and viscosity of liquid Sn–Zn alloys

In this work, data for liquid SnZn alloys with Na addition are presented. The thermophysical properties, viscosity, density and surface tension were measured using the discharge crucible method (DC). The experiments were conducted for Sn15Zn alloys with 0.1, 0.2, 0.5, 1.0, 3.0 and 5.0 at % Na. The measurements were performed over a temperature range of 548–823 K. The results show that the addition of Na to Sn15Zn (at. %) causes increased density and viscosity, and decreased surface tension in comparison to eutectic SnZn alloy. The new surface tension experimental data were compared with the corresponding values calculated by the Butler model, while the viscosity data were compared with models predicted values obtained by the Sichen-Boygen-Seetharaman, Seetharaman-Sichen, Kozlov-Romanov-Petrov, Kaptay and Gasior models, using thermodynamic input data. Correlation analysis between modelled and experimental data was performed.

The Effect of Substrate Microstructure on the Heat-Affected Zone Size in Sn-Zn Alloys Due to Adjoining Ni-Al Reactive Multilayer Foil Reaction

The rapid release of energy from reactive multilayer foils can create extreme local temperature gradients near substrate materials. In order to fully exploit the potential of these materials, a better understanding of the interaction between the substrate or filler material and the foil is needed. Specifically, this work investigates how variations in local properties within the substrate (i.e. differences between properties in constituent phases) can affect heat transport into the substrate. This can affect the microstructural evolution observed within the substrate, which may affect the final joint properties. The effect of the initial substrate microstructure on microstructural evolution within the heat-affected zone is evaluated experimentally in two Sn-Zn alloys and numerical techniques are utilized to inform the analysis.

Synthesis and Characterization of Nanoporous SnO2 Thin Film

SnO2 is a kind of typical n-type semiconductor material. Due to its excellent performance in conductivity, optics, thermal stability and corrosion resisting, it has been widely applied in fields of gas sensor, solar cell, chemical electrode materials. A novel synthesis route, originated from dealloying of Sn-Zn alloys films in hydrochloric acid (HCl) solution and then thermal treating, has been developed for the preparation of SnO2 films with three-demensional (3D) nanoporous. The influences of the HCl solution concentration and immersion time on crystal structure and morphology have been investigated. Porous structure and fracture surface morphology of the samples were characterized by field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The results indicated that the corrosion weight loss of Zn increased with the increasing of immersion time in HCl solution。An average pore diameter of the porous SnO2 films is 50~200nm after heat treatment at 500°C for 2 hours. XRD patterns show that the films are SnO2 with rutile structure.

Thermodynamic, structural and surface properties in Sn–Zn melt at 750 K

Thermodynamic, microscopic and surface properties of liquid Sn–Zn alloys at 750 K are reviewed in the framework of different statistical mechanical models. Flory’s model and quasi-chemical approximation (QCA) have been considered to deduce information on the concentration dependence of the thermodynamic and structural properties. The size-dependent atomic interaction has got special attention in Flory’s model, while in QCA the atomic interaction leading to the formation of like-atom clusters is assumed. Both models predict almost the same value of the interaction energy parameter in the Sn–Zn alloys, and it is found to be temperature dependent. The asymmetry in the thermodynamic properties of the alloys is explained to a great extent, and the analysis of the microscopic properties suggests that the Sn–Zn alloys are weakly segregating in nature throughout the whole range of the composition. Meanwhile, the validity of these models in describing the thermodynamic behaviour of the alloys is also examined. QCA is found to be more appropriate choice for the study of the energetics of the Sn–Zn alloys at 750 K. The comparative analysis of the surface properties under different assumptions reveals that self-associating mixture method better explains the surface behaviour in the alloys. The study indicates nonlinear variation in the concentration dependence of both the surface concentration and the surface tension of the alloys. The surface tension is found to increase with increase in Zn concentration, and the surface of the alloys is enriched with Sn atoms which segregate to the surface.

Effect of Copper and Zinc on Microstructures, Melting Points and Corrosion Resistance of Sn-Zn-Cu-Bi Soldering Alloys

Sn-Zn alloy is one of the Pb-free systems that are promising because of its relatively low melting temperature and low cost. However, Zn exhibits poor corrosion and oxidation resistance that hinders its soldering applications. The objective of this research is to study the effect of Zn and Cu alloying contents on the Sn-Zn performance. Four compositions of Sn-Zn alloys were studied in this research including: Sn-7Zn, Sn-9Zn, Sn-9Zn-2Cu-Bi, and Sn-9Zn-4Cu-Bi. The microstructures were studied using Optical Microscope (OM) and Scanning Electron Microscope (SEM). The melting temperatures and corrosion resistance of the alloys were evaluated by Differential Scanning Calorimeter (DSC) and Potentiodynamic Polarization technique, respectively. The results showed that an increase in the Cu-to-Zn ratio led to better corrosion resistance. The selective corrosion of the Zn-rich phase could be visibly observed, with OM, on the post-corrosion samples. With the Cu alloying, the Cu and Zn formed an intermetallic compound resulting in a higher value of Ecorr. However, the higher Cu content caused a significant increase in the liquidus temperature due to the Cu-Zn intermetallic compound, of which the melting temperature is higher than 400 °C, resulting in an incomplete melting at low temperature.

Fabrication and Superconducting Properties of the Bronze-Processed $\mbox{Nb}_{3}\mbox{Sn} $ Multifilamentary Wire Using Cu–Sn–Zn Alloy Matrix

We developed several new Cu-Sn-Zn-(Ti) alloys, which are so-called “CSZ alloy,” for practical bronze-processed Nb 3 Sn wires. Several CSZ alloys were fabricated via the Mizuta method. The Zn was uniformly dissolved in the α phase of the Cu-Sn alloy, and the Zn-Ti compounds were not found in the CSZ alloy. Various 19 Nb-filament CSZ Nb 3 Sn precursor wires were fabricated using CSZ matrices with different Sn and Zn nominal compositions. We also found that the CSZ/Nb composites showed excellent workability at room temperature. In this paper, changes in microstructure and superconducting properties of Nb 3 Sn wires with different CSZ matrices as a function of the heat treatment condition were investigated. We clearly observed that the amount of Zn in the matrix remained constant after the Nb 3 Sn formation. Thicker Nb 3 Sn layers were formed by the Zn addition. T c transitions of about 18 K have been obtained. Finally, we have succeeded in fabricating multifilamentary wires using CSZ matrices through the restacking method. The number of Nb filaments is 7771 with a diameter of 3.4 μm. The effect of the Zn addition on microstructures and superconducting property of the CSZ wires are also reported.

Ti addition to enhance corrosion resistance of Sn–Zn solder alloy by tailoring microstructure

The effect of trace addition of Ti on the corrosion behavior of Sn–9Zn (wt.%) solder alloy in NaCl solution was investigated using polarization and electrochemical impedance spectroscopy techniques. It is found that the corrosion resistance of Sn–9Zn alloy can be significantly enhanced by adding 0.05wt.% of Ti, evidenced by much lower corrosion current density, lower passive current density and higher impedance. Such enhancement results from the refinement of Zn-rich precipitates within the microstructure, which is conducive to forming a relatively more protective passive film on the surface of the modified alloy. This would be an important finding in the design of novel Sn–Zn solder alloys in electronic assemblies operating under aggressive conditions.

Recycling of metals from waste Sn-based alloys by vacuum separation

In order to recycle waste Sn-based alloys, the vapor–liquid phase equilibrium composition diagrams of Sn–Pb, Sn–Sb and Sn–Zn binary systems were calculated. The calculated results indicate that Pb, Sb and Zn can be separated from Sn effectively. Based on the above calculation, the industrial experiments of vacuum distillation of Sn–Pb alloy, Sn–Pb–Sb alloy, Sn–Pb–Sb–As alloy, crude Sn and Sn–Zn alloy with different contents were carried out. The experimental results show that Pb (>99% Pb) and Sn (≤0.003% Pb) were obtained simultaneously while Sn–Pb alloy was subjected to vacuum distillation; the crude Sn (>90% Sn, ≤ 2% Pb, ≤6% Sb) and crude Pb (≤2% Sn) were obtained simultaneously while a single vacuum distillation was carried out for Sn–Pb–Sb alloy; the Pb and Bi contents in the Sn ingot (99.99% Sn) achieve the grade A of GB/T 728—2010 standard, more than 50% of As and Sb was removed after vacuum distillation of crude Sn; Zn (<0.002% Sn) and Sn (about 3% Zn) were obtained while vacuum distillation of Sn–Zn alloy was conducted at 1173 K, 20–30 Pa for 8–10 h.

Self-Regulation of Cu/Sn Ratio in the Synthesis of Cu2ZnSnS4 Films

There has been a tremendous recent surge of interest in copper zinc tin sulfide (Cu2ZnSnS4, CZTS) as a photovoltaic material, because its optical and electronic properties are well-suited for solar cells, and its elemental constituents are abundant in the earth’s crust. Here we have studied the formation mechanisms of CZTS films, and the factors that control the cation stoichiometry during ex situ sulfidation of precursor Cu–Zn–Sn alloy films in a closed isothermal system. We find that the Cu/Sn ratio in CZTS is self-regulating and approaches 2, regardless of the initial composition of the precursor films, provided that adequate Sn is available in the sulfidation system. If precursor films are initially tin rich, excess Sn evaporates in the form of SnS. If precursor films are initially Sn-deficient, the inclusion of solid Sn in the sulfidation ampule readily generates SnS vapor, which mitigates the films’ Sn deficiency to return the Cu/Sn ratio to 2. When sulfidized for sufficiently long times at sufficie...

Interfacial reactions between solid Ni and liquid Sn-Zn alloys

The limitation of the harmful lead-containing solders used in the electronics and other industry applications change lead with another metals. Interfacial reactions between Sn-Zn alloys and Ni substrate after annealing at 400 and 450?C were studied. Three intermetallic compounds Ni3Sn4, T1, ?-Ni5Zn21 and liquid Sn were observed in the Ni/Sn-Zn diffusion couples. Scanning electron microscope was used for the investigation of the microstructure. The microhardness measurement of the intermetallic layers was also performed.

Evolution of Metallographic Parameters during Horizontal Unidirectional Solidification of Zn-Sn Alloys

In the present research the horizontal directional solidification of Zn-Sn alloys (Zn-4wt.%Sn, Zn-6wt.%Sn, Zn-10wt.%Sn and Zn-30wt.%Sn) was carried out by extracting heat in two opposite directions. For this purpose, ceramic molds, a muffle, a horizontal furnace with two heat extraction systems at the ends, a measurement, acquisition and recording temperature system, eight K-type thermocouples and an electronic recorder were used. The main parameters involved in the columnar-to-equiaxed transition, CET, were: the moment of start and end of solidification at each position under consideration, cooling rates, the average temperature gradients and critical temperature gradients at the CET. Also, metallographic parameters evolution (secondary dendritic arm spacing) was analyzed in function of the position in the sample and correlated with thermal parameters. The values of the critical thermal gradients for each composition were 0.01°C/cm (right side) and 0.23°C/cm (left side) for Zn-4wt%Sn, 0.25°C/cm (right side) and 0.41°C/cm (left side) for Zn-6wt%Sn, 1.4°C/cm (right side) and 1.7°C/cm (left side) for Zn-10wt%Sn and -0.05°C/cm (right side) and 0.15°C/cm (left side) for Zn-30wt%Sn.

Electrodeposition and characterization of Zn-Sn alloy coatings from a deep eutectic solvent based on choline chloride for corrosion protection

With the aim of obtaining high corrosion resistant Zn–Sn alloy coatings from an ionic liquid, the effects of electrodeposition potential and electrolyte composition on the electrodeposition behavior, film composition, morphology and corrosion performance were investigated. Cyclic voltammograms indicate that Zn and Sn were co-deposited at distinct reduction potentials as pure Zn and Sn elements. In addition, the phase composition analysis also showed that the obtained Zn–Sn alloy deposits (8 wt.%–45 wt.% Zn) consist of a two-phase mechanical mixture of small aggregates of Zn and Sn metals. The Zn content of the alloy significantly increases as the electrodeposition potential and electrolyte Zn (II)/Sn (II) ratio increase. The corrosion performance study of the obtained Zn–Sn coatings showed that they have a passivation behavior and their corrosion resistance increases as the alloy-Sn content increases. To improve their morphological properties, ethylene diamine tetraacetic acid additive was introduced into the electrolyte and greatly improved the morphology and corrosion resistance of the deposits. For the first time, it was shown that high corrosion resistance Zn–Sn coatings can be obtained from ionic liquids. Copyright © 2014 John Wiley & Sons, Ltd.

Application of MIVM for Sn-Zn System in Vacuum Distillation

The activities of components of Sn-Zn system were predicted based on the molecular interaction volume model (MIVM). The separation coefficients and the vapor–liquid phase equilibrium of Sn-Zn system were also predicted using the MIVM. The predicted results indicated that the content of tin in the vapor phase was 0.000052 wt pct, while in the liquid phase, it was 99.98 wt pct at 1173 K (900 °C). Experimental investigations into the separation of Sn-Zn alloy by vacuum distillation were carried out for the proper interpretation of the predicted results. The effects of vacuum level (15 to 200 Pa), distillation temperatures [873 K to 1273 K (600 °C to 1000 °C)], and soaking time (20 to 60 minutes) were studied. The experimental results indicated that the content of tin in the vapor phase was 0.001 wt pct, while in the liquid phase, it was 99.98 wt pct at 1173 K (900 °C). The experimental results match well with the predicted data, suggesting that the MIVM is a suitable model for Sn-Zn system.

Effect of Phase Composition on the Anodic Dissolution and Passivation of Zinc-based Alloys

The influence of phase composition on the anodic behavior of electrolytic zinc-based alloys in alkaline solutions was investigated. The following materials were studied: Zn-Sn alloys consisting solely of Zn and Sn crystallites in a mechanical mixture, Zn-Fe, Zn-Co, and Zn-Ni alloys consisting of both solid solutions and intermetallic compounds. The anodic behavior of low-alloy solid solutions is similar to that of pure Zn. Solid-solution alloys consisting of an-phase had a distinctive feature: the descent of the anode current prior to the complete passivation takes place at more positive potentials compared to pure zinc and its mechanical mixtures. The same sequence of anodic dissolution and passivation of zinc alloys as for the pure zinc anode polarization were observed during anodic polarization of both solid solutions and intermetallic phases of zinc alloys. Alloying led to a change in the thermodynamic and kinetic characteristics of anodic processes. Typical peaks of anodic behavior of Zn and Sn were observed on the voltammetry curves of a broad range of heterogeneous Zn-Sn alloys. Peak currents depended on the alloy composition. The dependence between the alloy phase composition and the corresponding electrochemical behavior can be used in determination of the phase composition.