Sn-Bi Alloys Research Articles

Permeation behavior of low-melting-point Sn–Bi alloy in the fiber channel of pine wood

Wood and metal are the two most common materials, both with distinct advantages and disadvantages. Through the metallization process, the inherent defects of the two materials can be avoided, so that the composite material exhibits excellent structural properties and anisotropy. In this study, the pine wood was pretreated with dilute ammonia (5%), and then the low melting point Sn–Bi alloy was filled into the pine fiber without lignin at 180 °C and 3000 Pa. The density of metallic wood is about 3 times that of pine, while the impact toughness can be up to 2 times that of pine. By building the capillary buddle model, the filling mechanism of molten metal in pine wood was analyzed, and it was clear that high vacuum, high temperature, large porosity and large tracheid diameter are the conditions for rapid penetration. The conductive anisotropy was found on metalized wood, making metalized wood available in different places with requirements for electromagnetic shielding and antistatic.

Microstructure characterization and tensile properties of directionally solidified Sn-52 wt% Bi-1wt% Sb and Sn-52wt% Bi-2wt% Sb alloys

Sn-Bi-based Thermal Interface Materials (TIM) are adequate alloys to promote heat dissipation in power electronics. However, despite the necessary thermal connection, mechanical support for different components and substrates are of prime importance in microelectronic devices. In this framework, the effects of Antimony (Sb) additions on the microstructure and tensile properties of the Sn-52 wt% Bi alloy are investigated. Various Sn-Bi(-Sb) samples solidified at different cooling rates and two levels of Sb-containing alloys allow a comprehensive examination of length scales of either dendritic or eutectic microstructures. A number of experimental techniques are used here to permit a sound analyses of the ternary Sn-Bi(-Sb) alloys: transient directional solidification, optical microscopy (OM), triangle and intercept quantification methods, scanning electron microscopy (SEM), x-ray fluorescence (XRF), x-ray diffraction (XRD), tensile tests and fractography. The addition of Sb enhances the nucleation of primary dendritic trunks, which resulted in a decrease in the primary dendritic arm spacing (λ1) by about 5 times for the Sn-52 wt% Bi-2 wt% Sb alloy as compared to the results for the binary Sn-Bi alloy. The relationships found for tensile properties as a function of the secondary dendritic arm spacing (λ2) demonstrate that Sb additions increase the alloy strength while preserving the ductility. This is due to very thin SnSb intermetallic particles formed in the Sn-rich dendritic matrix. The influence of λ2 variation on both the yield and ultimate strengths is roughly insignificant while the ductility varies strongly between 14.4% and 52% for samples solidified from 0.05 °C/s to 5.0 °C/s respectively. When 2.0 wt% Sb is added, there is a maintenance in the levels of ductility as those found for the binary Sn-Bi alloy. This occurs especially for very refined dendritic and eutectic microstructures samples, which also exhibit a ductile fracture mode.

Design of multicomponent Mg–Al–Zn–Sn–Bi alloys with refined microstructure and enhanced tensile properties

Owing to the low alloying content in commercial wrought Mg alloys, their strengthening potential is greatly suppressed. It is difficult to achieve the synergy of high strength and formability for Mg alloys. In the present work, a novel high-alloyed Mg–6Al–1Zn–1Sn-0.5Bi (AZTB6110) alloy was designed by multi-component composition design and subjected to a fabrication route coupling sub-rapid solidification and controlled rolling. The alloy has excellent tensile properties, i.e. yield strength (YS) of ~260 MPa, ultimate tensile strength (UTS) of ~363 MPa and elongation of ~15%. The role of Al content (4, 6 and 8 wt %) on microstructure and tensile properties was systematically investigated in the AZTB alloys. When the Al content reaches 6 wt %, the combined pining effects of nano- and submicro-precipitates (Mg17Al12 and Mg2Sn) hinder the grain growth and result in the finest grain size (~3 μm) among the studied alloys. The refined grains as well as densely dispersed fine Mg17Al12 and Mg2Sn particles result in the best tensile yield strength in AZTB6110 compared to the other alloys. Meanwhile, the high ductility is benefited from the strong work-hardening capacity resulting from the interaction of dislocations with Al, Zn, Sn and Bi solutes and numerous nano-precipitates. Such a designed alloy helps to improve the development of high-alloyed multicomponent Mg alloys with high performance, which broadens the composition range and application of traditional wrought Mg alloy sheets.

Large-Scale Sonochemical Synthesis of Bi-Sn Eutectic Alloy Nanoparticles.

Lead-free Bi-Sn alloy is an alternative solder material with a low eutectic melting temperature and environmental compatibility. Although extensive research has been conducted on this Bi-Sn eutectic alloy, a lack of facile synthetic methods with scalability hinders the implementation of finepatterned interconnectors for emerging electronic applications. In this study, we employed a facile sonochemical synthetic method to synthesize Bi-Sn alloy nanoparticles in large quantities. Highenergy ultrasonication treatment of Bi-Sn bimetallic particles resulted in nanoparticle formation with repeated formation, growth, and collapse of induced gas bubbles. The size of the nanoparticles was controlled from 92 to 506 nm of the mean diameter with variations in ultrasonication power and irradiation time. The nanoparticles exhibited a stable eutectic melting point at 139.8 °C. Interestingly, the sonochemically synthesized nanoparticles exhibited coexistence of metastable Bi2Sn and stable Bi-Sn phases. Finally, we demonstrated that Bi-Sn eutectic nanoparticles could be synthesized at a gram scale of approximately 1.7 g for future mass production.

Microsegregation model including Soret effect: an application for Sn-Bi alloy

We present an application of a microsegregation model that takes into account the Soret effect. This model, summarized here, lies in the context of the evaluation of thermodiffusion influence in alloys solidification. Initially, we deal with the thermodiffusion effect on the microsegregation scale. Subsequently, the Soret effect on macrosegregation shall be analyzed. The present model was conceived with similar considerations compared to the Gulliver-Scheil approach. A dimensionless parameter emerged from the model, which is potentially useful for assessing the Soret effect on the solidification of binary alloys. In the present work, this parameter was applied to an Sn-Bi alloy. The microsegregation model including the Soret effect can be widely used in the study of solute redistribution.

Microstructure and Mechanical Behavior of Hot Extruded Aluminum/Tin-Bismuth Composites Produced by Powder Metallurgy

In this study, Al-BiSn composites were synthesized by a combination of microwave sintering and hot extrusion processes. The structural, morphological, mechanical, and thermal properties were investigated to elucidate the role of Bi60Sn40 (BiSn) alloy content (5, 10, and 15 wt.%) in modifying the properties of Al-BiSn composites. The X-ray diffraction (XRD) patterns confirmed the presence of aluminum and BiSn particles. Distribution of BiSn particles in Al-BiSn composites was confirmed by field emission scanning electron microscopy associated with energy dispersive X-ray analysis (FE-SEM-EDX). Results indicated that hot extruded Al-(15 wt.% BiSn) composite exhibits maximum hardness (78 ± 4 Hv) and tensile strength (185 ± 3 MPa), which were 117% and 58% improvements, respectively, compared to pure Al. This improvement in mechanical properties can be attributed to the strengthening effect of BiSn particles. A decline in the values of the coefficient of thermal expansion (CTE) with an increasing amount of BiSn particles reflects the enhanced thermal stability of developed Al-BiSn composites. The promising properties of Al-BiSn composites make them suitable for many industrial applications.

Improvement of microstructure and tensile properties of Sn–Bi–Ag alloy by heterogeneous nucleation of β-Sn on Ag3Sn

Different weight fractions (0, 0.5, 1.0, 2.0, and 3.0 wt%) of sliver (Ag) were used to dope Sn–Bi eutectic alloys in this study. The microstructure and tensile and thermal properties of Sn–Bi eutectic alloys doped with Ag were investigated. The results indicate that the addition of Ag increases the solidification temperature and reduces the fusing latent heat of alloy, but it has no significant effect on the melting point of the alloy. According to the electron backscattered diffraction (EBSD) analysis and calculation of the disregistry between ε-Ag3Sn and β-Sn, ε-Ag3Sn can be used as the heterogeneous nucleation substrate of β-Sn, thus refining lamellar eutectic spacing. The orientation relationship between the ε-Ag3Sn phase and the β-Sn phase was as follows: [ 0 2‾1 ]Ag3Sn//[ 0 1 2 ]β-Sn, (0 1 2)Ag3Sn//(‾1 2‾1) β-Sn, and [‾1 2 0 ]Ag3Sn//[ 0 1 2 ]β-Sn, (2 1‾1)Ag3Sn//(‾1 2‾1)β-Sn. The tensile strength of the eutectic Sn–Bi alloy with addition of 1.0 wt% Ag reached 72 MPa, which was 20% higher than that of the original alloy. The analysis showed that Ag doping increase the tensile strength of the eutectic Sn–Bi alloy, because of fine grain strengthening and second phase strengthening mechanism

A low-temperature limit for growth of ZnO nanowires by using of laser ablation processes

The contribution deals with growth of ZnO nanowires on metal catalysts by using of pulsed laser deposition and with the influence of growth temperature. The process of nanowires preparation comprised two technological steps—both were based on pulsed laser ablation processes: (1) production of metal nanoparticles by laser ablation in liquids and (2) pulsed laser deposition of ZnO nanowires by ablation of ZnO target on substrate with metal nanoparticles. Nanoparticles from various metals (Au, Ag, Ni, Cu, Al, Mg, Zn, Sn and BiSn alloy) were prepared by pulsed laser ablation at 1064 nm in deionised water. Colloids contained metal nanoparticles were applied on Si (100) substrates, and after drying, nanoparticles served as catalysts of VLS crystallisation. Temperatures in interval 600—200 °C were experimentally compared for the nanowires growth with applied ablation laser working at 248 nm. The lowest achieved temperature value for growth of ZnO nanowires was 425–450 °C. However, among applied metals Cu and Al nanoparticles only successfully catalysed ZnO nanowires at this temperature. Properties of prepared samples were investigated by scanning electron microscopy and photoluminescence. Experimental results revealed that along with the growth temperature, selection of proper metal catalyst is also important factor for nanowires crystallisation.

Effect of bismuth–tin composition on bonding strength of zinc particle–mixed copper nanoparticle/bismuth–tin solder hybrid joint

In this study, the effect of Bi–Sn composition on the bonding strength of Zn-mixed hybrid joints composed of SiC/Cu and SiC/direct bonded copper (DBC) was examined. For both joints, the bonding strength exhibited a similar dependence on Bi–Sn composition, and the maximum strength obtained for the average Bi fraction in the Bi–Sn alloy particles was 38.2 wt%. This composition is more Sn-rich than the eutectic composition of the Bi–Sn alloy. The bonding strength of the SiC/Cu joints was lower than that of the SiC/DBC joints throughout the entire Bi–Sn alloy composition range. The degree of Bi segregation at the interfacial region decreased with a decreasing Bi fraction in the Bi–Sn particles and was correlated with the bonding strength for the Bi fraction below 38.2 wt%. Defects such as voids and cracks were also observed in the bonding layer, which were likely a result of the difference in the bonding strengths between the SiC/Cu and SiC/DBC joints. Furthermore, delamination of the bonding layer at the interface was observed in the joint that had Sn particles as the starting material. These results indicate that Zn mixing in the hybrid joint enables the reduction of the Bi fraction of the Bi–Sn alloy, leading to improved bonding strength.

Two-Dimensional Amorphous SnOx from Liquid Metal: Mass Production, Phase Transfer, and Electrocatalytic CO2 Reduction toward Formic Acid.

Liquid metal forms a thin layer of oxide skin via exposure to oxygen and this layer could be exfoliated by mechanical delamination or gas-injection/solvent-dispersion. Although the room-temperature fabrication of two-dimensional (2D) oxide through gas-injection and water-dispersion has been successfully demonstrated, a synthetic protocol in nonaqueous solvent at elevated temperature still remains as a challenge. Herein we report the mass-production of amorphous 2D SnOx nanoflakes with Bi decoration from liquid Sn-Bi alloy and selected nonaqueous solvents. The functional groups of the solvents play a key role in determining the final morphology of the product and the hydroxyl-rich solvents exhibit the best control toward 2D SnOx. The different solvent-oxide interaction that facilitates this phase-transfer process is further discussed on the basis of DFT calculation. Finally, the as-obtained 2D SnOx is evaluated in electrocatalytic CO2 reduction with high faradaic efficiency (>90%) of formic acid and stable performance over 10 h.

Surface and transport properties of liquid Bi–Sn alloys

The new Bi–Sn surface tension experimental data have been obtained by the pinned drop method for temperatures ranging from 623 to 1123 K and were subsequently compared with the model predicted values as well as with the literature data. Taking into account endothermic mixing in liquid Bi–Sn alloys, the surface properties (surface tension and surface segregation) were described by the Quasi-Chemical Approximation (QCA) for regular solution and the Self Association Model (SAM) aiming to estimate the effects of demixing on these properties. In addition, the transport and structural properties of Bi–Sn melts were analysed by theoretical models developed in the framework of statistical mechanics in conjunction with the Quasi-Lattice Theory (QLT) and Faber-Ziman Theory. The abovementioned properties are involved in the development of complex solder materials based on the Bi–Sn system.

Preparation of Sn–58Bi solder powder by shearing liquids into complex particles

In the present work, Sn–58Bi solder powder that had a core–shell structure with particle diameter between 1.0 and 30.0 μm was prepared by shearing liquids into complex particles (SLICE). Molten Sn–58Bi alloys were dispersed into spherical microstructure coated with organic matter using high-speed mechanical agitation and dispersant, which was a mixture of paraffin and polyethylene glycol (PEG). Microstructural evolution of particles was investigated under variations in stirring rate (5000 rpm, 10,000 rpm, or 15,000 rpm) and cooling methods (air cooling, water cooling, or ice water cooling). The optimal Sn–58Bi solder powder that had a diameter ranging from 1.9 to 27.6 μm was obtained in a stirring time of 5 min, a stirring rate of 15,000 rpm, and a cooling method of ice water cooling. Such microparticles with favorable size are promisingly used in electronic industrial applications.

Whisker inhibited Sn–Bi alloy coating on copper surface to increase copper bonding strength for signal loss reduction of PCB in high-frequency

Introducing Bi in the coating of Sn on copper surfaces for chemical bonding with prepreg was proposed to inhibit the serious whisker growth of Sn in the post–application process. The desired bonding strength and low roughness of copper surfaces (Ra = 0.5 μm) coated with this Sn–Bi alloy were both obtained under characterizations of peeling strength test and roughness measurement. Scanning electron microscopy (SEM) and X–ray photoelectron spectroscopy (XPS) confirmed that the high bonding strength is related to the high content of SnO2 in as–coated Sn–Bi alloy and the plating time with 180 s gives rise to the optimized bonding strength. Agilent Vector Network Analyzer (VNA) affirmed the lower signal loss (7 dB/m@10 GHz) in comparison with that treated with conventional brown–oxidation. Accordingly, the Sn–Bi coating on copper surface is suggested to be a candidate for layer bonding in high frequency PCB.

Microstructure and thermal properties of Bi-Sn eutectic alloy

AbstractAlloys based on Sn and Bi are considered to be one of the best soft lead-free solders due to their low melting temperature and low price. In addition, Bi-Sn alloy with a eutectic composition represents a promising candidate as a metallic phase change material (PCM) for use in the field of thermal energy storage (TES). The accurate knowledge of microstructural and thermophysical properties such as the latent heat of melting, thermal conductivity, specific heat capacity is of crucial importance for PCM selection. Thus, the aim of the current study has been to determine the microstructure, latent heat of melting and thermal conductivity of a eutectic alloy from the binary Bi-Sn system.

Study on thermophysical performance of Mg–Bi–Sn phase-change alloys for high temperature thermal energy storage

Mg-based alloys are potential high temperature phase change materials for thermal energy storage due to their high melting enthalpy, high thermal conductivity and excellent compatibility with Fe-based containment materials. This work mainly focuses on studying the microstructure and thermophysical characterization of Mg–Bi–Sn alloys phase change materials with 4 different components and their thermal energy storage performance. The experimental results show that the Mg–33Bi–17Sn, Mg–39Bi–17Sn and Mg–45Bi–17Sn alloys mainly consist of primary α-Mg phase and α-Mg + Mg2Sn + Mg3Bi2 eutectic structure, and the Mg–33Bi–23Sn alloy mainly consist of primary α-Mg phase, primary Mg2Sn + Mg3Bi2 phases and α-Mg + Mg2Sn + Mg3Bi2 eutectic structure. Their melting enthalpies are respectively 18.5 J/g, 168.8 J/g, 106.3 J/g and 140.3 J/g, while their melting temperatures are about 515 °C–525 °C. As from the results, the Mg–39Bi–17Sn alloy obtains the highest melting enthalpy, which attributes to its higher proportion of eutectic α-Mg + Mg2Sn + Mg3Bi2 structure. However, the Mg–45Bi–17Sn alloy shows the highest thermal conductivity. In addition, the melting point of Mg–39Bi–17Sn alloys increase by about 1.8 °C, and the melting enthalpy decreases by about 4.2% after 300 thermal cycling. Based on all results, the Mg–39Bi–17Sn alloy shows with great thermalphsycial performance and is expected to be used as thermal energy storage material.

Effect of Additional Element on Super Plasticity Deformation of Sn-Bi Alloys

Effect of Additional Element on Super Plasticity Deformation of Sn-Bi Alloys

Development and characterization of eutectic Sn-Zn, Sn-Ag, Sn-Bi and Sn-Cu solder alloys

AbstractThis paper reports the comparative study of the microstructure, melting point, hardness and electrical resistivity of as-cast eutectic Sn-8.8 wt.% Zn, Sn-3.5 wt.% Ag, Sn-43 wt.% Bi and Sn-0.7 wt.% Cu lead-free solder alloys. Sn-3.5 wt.% Ag eutectic solder alloy was found to have the lowest electrical resistivity of 1.91 μΩ · cm whereas the highest electrical resistivity of 14.17 μΩ · cm was observed in the case of Sn-43 wt.% Bi eutectic solder alloy. The lowest melting point of 141.60°C was observed in the case of Sn-43 wt.% Bi eutectic alloy whereas the highest melting point of 243.28°C was observed in the case of Sn-3.5 wt.% Ag solder alloy. The results of the various solder alloys were compared with the properties of commercially available Sn-38.1 wt.% Pb eutectic solder alloy.

Microstructural modification of Sn–Bi and Sn–Bi–Al immiscible alloys by shearing

ABSTRACTSn–20 wt-%Bi and immiscible Sn–20 wt-%Bi–1 wt-%Al alloys were used to understand the effect of high-intensity shearing on microstructural refinement. Novel ACME (Axial Centrifugal Metal Expeller) shearing device, based on axial compressor and rotor–stator mechanism to generate high shear rate and intense turbulence, was used to condition the melts prior to solidification. Microstructure in the Sn–Bi alloy deviated from dendritic grains with coarse eutectic pockets under conventional solidification to compact grains with well-dispersed eutectic under semisolid-state shearing. Decreasing the shearing temperature and increasing shearing time increased the globularity of grains. Following shearing, remnant liquid solidified into fine grain structure. In the immiscible Sn–Bi–Al alloy, shearing produced uniform dispersion of refined Al-rich particles in Sn-rich matrix as opposed to severe segregation under conventional solidification. The primary effect of shearing appears to originate from the thermo-solutal homogenisation of the melt and its effect on interface stability during solidification.

The significance of strain weakening and self-annealing in a superplastic Bi–Sn eutectic alloy processed by high-pressure torsion

A cast Bi–Sn eutectic alloy was processed by high-pressure torsion (HPT) at room temperature and stored at room temperature for durations of up to 91 days in order to investigate the effect of self-annealing. The HPT processing produces grain refinement but hardness measurements show there is strain softening with lower microhardness values than in the initial as-cast material and with hardness values that decrease with increasing amounts of imposed torsional strain. This softening is attributed to a loss of precipitates within the Sn and Bi phases during the processing operation. In self-annealing at room temperature, the microhardness increases significantly due to reprecipitation and there is also a minor increase in grain size with increasing time of storage. It is demonstrated by tensile testing that the HPT-processed Bi–Sn alloy exhibits superplastic behavior with elongations of up to >1000% after storage for 35 days and with an associated strain rate sensitivity close to ∼0.5. Grain boundary sliding plays an important role in superplastic flow and it is shown that maximum sliding occurs on the Bi–Bi interfaces where this is consistent with estimates of the coefficients for grain boundary diffusion in the Bi–Sn alloy.

Antimicrobial effect, electronic and structural correlation of nano-filled Tin Bismuth metal alloys for biomedical applications

In this work silver vanadate (AgVO3) nano-rods were successfully synthesized using chemical precipitation route and doped in hypo (Sn 99%- Bi 1% ) and hyper (Sn 3%- Bi 97% ) -eutectic tin-bismuth (Sn-Bi) alloy. Nanostructured metal alloy was synthesized using powder compact metallurgy technique as a new low cost and time-consuming route. Effects of the AgVO3 nano-rods content on the band structure of (Sn-Bi) alloy has been investigated through electronic transition studied via ATR ultraviolet/visible spectrophotometric and Hall Effect measurements. Antimicrobial studies for pathogenic Gram negative as well as Gram positive bacteria were also investigated and correlated to the analyzed electronic and optical properties. The work a debate avenue for probability controllingthe microbial growth and to correlate electronic properties of (Sn-Bi) alloy along with their antimicrobial properties.