Sn Bi Research Articles

CALPHAD-guided alloy design of Bi-modified Al–Sn bearing alloy with multiphase composite structure and optimal self-lubricating property

Through primary phase diagram analysis and thermodynamic calculation of Al–Sn, Al–Bi and Sn–Bi binary systems, Bi element was ensured to be a suitable alloying element possibly introducing granular Bi-rich precipitates and increasing the self-lubricating property of Al–Sn bearing alloy. Through calculation of excess free energy of liquid (Gexcessliq) in Al–Sn–Bi ternary system, it’s further proven that the segregation of Bi in Al can be suppressed by Sn element. Pseudo-binary phase diagrams of Al–Sn–xBi (wt%, x = 0, 1, 2, 3) were obtained through CALPHAD method, it’s found that Al–20Sn and Al–20Sn–1Bi alloys are composited of α-Al and Sn-rich secondary phases (SPs). However, Bi will be precipitated from the Sn-rich SPs in Al–20Sn–2Bi and Al–20Sn–3Bi alloys which are thus composited of three phases (α-Al, Sn-rich SPs and Bi-rich precipitates). The Al–20Sn–xBi (wt%, x = 0, 1, 2, 3) alloys were prepared with the guidance of CALPHAD. The microstructures match the calculation results well, fine and granular Bi-rich precipitates can be observed only in Al–20Sn–2Bi and Al–20Sn–3Bi alloys. Friction coefficients of alloys firstly decrease to 0.23 and then increase to 0.32 with Bi content increasing from 0 wt% to 3 wt%. The granular Bi-rich precipitates can improve the self-lubricating property of Al-Sn alloy. However, the increasing brittleness will lead to decrease of self-lubricating property when Bi content surpasses the critical value.

Thermomechanical fatigue resistance of low temperature solder for multiwire interconnects in photovoltaic modules

Novel interconnect technologies leveraging low melting temperature solders, such as multiwire interconnects, are being deployed in photovoltaic (PV) modules for improved reliability through interconnect redundancy and lower thermal loads during interconnection and lamination. However, the equivalency of standardized accelerated testing to field conditions has not yet been established for these emerging technologies. In this study, the thermomechanical fatigue resistance of low temperature solder alloys is investigated and compared to that of conventional SnPb to assess the acceleration behavior of these alloys. While InSn is shown to have sufficient thermomechanical fatigue resistance on the order of that of SnPb, these results indicate Sn–Bi alloys may have poor thermomechanical fatigue resistance at field conditions. The results also show that Sn–Bi alloys have thermal cycling acceleration factors of less than one. This indicates that the standardized accelerated thermal cycling test, such as that in IEC 61215, will produce misleading results for Sn–Bi alloys and that unique testing is required for this PV module architecture. Though accelerated thermal cycling may be a meaningful qualification test for SnPb solder joints, these results suggest that mechanical loading may be a more appropriate test for Sn–Bi multiwire interconnects. This is due to the distinct processing and geometry of multiwire interconnects which may allow for mechanical, rather than strictly metallurgical interconnections.

Achieved high energy storage property and power density in NaNbO3-Bi(Sn0.5Ni0.5)O3 ceramics

• 0.88NN-0.12BSN ceramic possesses a desired W rec of 2.01 J/cm 3 and η of 80.3%. • 0.88NN-0.12BSN ceramic exhibits a high power density ( P D = 88.16 MW/cm 3 ). • 0.88NN-0.12BSN ceramic exhibits a large current density ( C D = 979.59 A/cm 2 ). • Energy storage properties possess excellent frequency and temperature stability. Recently, NaNbO 3 has aroused the enthusiasm of researchers due to its potential application for energy storage. In this work, lead-free (1- x )NaNbO 3 - x Bi(Sn 0.5 Ni 0.5 )O 3 ceramics or (1- x )NN- x BSN in abbreviation were prepared by the traditional solid-state reaction method. The microstructure, dielectric properties and energy storage performances of (1- x )NN- x BSN ceramics were investigated in detail. Superior breakdown strength and underdamped discharge abilities are achieved in 0.88NN-0.12BSN ceramic with a maximum recoverable energy storage density (2.01 J/cm 3 ) and high efficiency (80.3%) at 310 kV/cm. The excellent stability of energy storage properties in the frequency range from 100 Hz to 1 MHz, and the temperature range from −150 to 300 °C, are observed in the 0.88NN-0.12BSN ceramic. Furthermore, the 0.88NN-0.12BSN ceramic exhibits a large current density (~979.59 A/cm 2 ), an extremely high power density (~88.16 MW/cm 3 ) and stable discharge period of about 51 ns.

Sn and Bi whisker growth from SAC0307-Mn07 and SAC0307-Bi1-Mn07 ultra-thin film layers

In the past years, the use of low silver content SAC0307 (99Sn0.3Ag0.7Cu wt%) solder alloy grew considerably due to its good soldering quality. In the latest version of this alloy, manganese, and bismuth are used to improve further its soldering parameters. In this study, a reliability issue, the whisker growth from SAC0307-Mn07 and SAC0307-Bi1-Mn07 solder alloys was investigated. Ultra-thin films (in 100–150 nm thickness) were vacuum evaporated from the investigated alloys onto Cu substrates. The samples were stored at laboratory conditions for 28 days. Whisker growth was followed by a scanning electron microscope, and the ultra-thin film layers structures were investigated in focused ion beam cuts. In the case of the SAC0307-Mn07, the mechanical stress due to the intermetallic layer growth resulted in whisker formation right after the layer deposition. However, Bi addition could increase the stress relaxation ability of the ultra-thin film layer; the whisker formation started only three days after the evaporation in the case of the SAC0307-Bi1-Mn07 layer. Besides, the SAC0307-Bi1-Mn07 alloy could entirely suppress the formation of filament-type whiskers that might cause reliability issues in microelectronics. Furthermore, a unique phenomenon was observed that the SAC0307-Bi1-Mn07 layer produced mostly Bi–Sn whisker couples.

Superconductivity of the Bi–Sn Eutectic Alloy

We report on the results of investigations of superconductivity in the Bi–Sn binary alloy with a eutectic concentration of 57 wt % of Bi and 43 wt % of Sn. The temperature and field dependences of the dc magnetization have been measured in the range of 1.8–20 K in magnetic fields of up to 20 kOe using a Quantum Design MPMS3 SQUID magnetometer. A two-stage phase transition with diamagnetism establishment temperatures of 8.55 and 5.1 K has been found. A phase diagram has been built. The coherence length for the first stage has been estimated. The field dependence of the irreversibility temperature has been determined. Positive curvature portions observed in the critical dependences have been interpreted using a model based on the proximity effect.

Interfacial Reactions and Mechanical Properties of Sn-58Bi Solder Joints with Ag Nanoparticles Prepared Using Ultra-Fast Laser Bonding.

The effects of Ag nanoparticle (Ag NP) addition on interfacial reaction and mechanical properties of Sn–58Bi solder joints using ultra-fast laser soldering were investigated. Laser-assisted low-temperature bonding was used to solder Sn–58Bi based pastes, with different Ag NP contents, onto organic surface preservative-finished Cu pads of printed circuit boards. The solder joints after laser bonding were examined to determine the effects of Ag NPs on interfacial reactions and intermetallic compounds (IMCs) and high-temperature storage tests performed to investigate its effects on the long-term reliabilities of solder joints. Their mechanical properties were also assessed using shear tests. Although the bonding time of the laser process was shorter than that of a conventional reflow process, Cu–Sn IMCs, such as Cu6Sn5 and Cu3Sn, were well formed at the interface of the solder joint. The addition of Ag NPs also improved the mechanical properties of the solder joints by reducing brittle fracture and suppressing IMC growth. However, excessive addition of Ag NPs degraded the mechanical properties due to coarsened Ag3Sn IMCs. Thus, this research predicts that the laser bonding process can be applied to low-temperature bonding to reduce thermal damage and improve the mechanical properties of Sn–58Bi solders, whose microstructure and related mechanical properties can be improved by adding optimal amounts of Ag NPs.

Influence of Sb2O3 Nanoparticles Addition on the Thermal, Microstructural and Creep Properties of Hypoeutectic Sn–Bi Solder Alloy

Here we investigate the effects (thermal, microstructural, and creep properties) of adding Sb2O3 nanoparticles to a hypoeutectic Sn-5 wt% Bi solder alloy. The Sb2O3-containing solder alloy was prepared by mechanically incorporating 0.5 wt% Sb2O3 nanoparticles into the Sn-5 wt% Bi solder alloy. The addition of nano-sized Sb2O3 particles to the Sn–Bi solder alloy increases the melting temperature, but only slightly. The main phases of the investigated solder alloys include the β-Sn and Bi-rich phases in addition to the crystalline phase of Sb2O3 nanoparticles. No other intermetallic compounds were observed in the β-Sn matrix. The tensile creep experiments have been carried out in the 303–363 K temperature interval under constant stresses ranging from 5.1 to 7.64 MPa. The creep parameters of both solders increased gradually with increasing creep temperature up to 333 K, after which they increased rapidly with relatively higher values. The creep parameters of the Sb2O3-containing solder alloys are smaller than that of Sb2O3-free solder alloys. The present solder alloys exhibit class-M creep behavior. The calculated stress exponent values and activation energy data for both solders could be related to dislocation climb through core diffusion as the dominant operating mechanism.

The Variations of Electron and Phonon Contributions to the Thermal Conductivity with Temperature in the Sn–Bi–In–Zn Alternative Lead-Free Solder Alloys

The goal of this paper is to measure the electrical and thermal conductivity variations with temperature in the unidirectional solidified quaternary Sn–Bi–In–Zn lead-free solder alloys for nine different compositions to determine the phonon thermal conductivity variation with temperature. The measurements of electrical and thermal conductivity variations with temperature were put into practice with the methods of four-point probe and longitudinal heat flow, respectively, and the electron and phonon thermal conductivity variations with temperature for the alloys were plotted. In addition, the temperature coefficient values for electrical and thermal conductivity were calculated.

Effect of Ga on the Oxide Film Structure and Oxidation Resistance of Sn-Bi-Zn Alloys as Heat Transfer Fluids.

The effect of gallium on the oxide film structure and overall oxidation resistance of low melting point Sn–Bi–Zn alloys was investigated under air atmosphere using thermogravimetric analyses. The liquid alloys studied had a Ga content of 1–7 wt.%. The results showed that the growth rates of the surface scale formed on the Sn–Bi–Zn–Ga alloys conformed to the parabolic law. The oxidation resistance of Sn–Bi–Zn alloys was improved by Ga addition and the activation energies increased from 12.05 kJ∙mol−1 to 22.20 kJ∙mol−1. The structure and elemental distribution of the oxide film surface and cross-section were found to become more complicated and denser with Ga addition. Further, the results of X-ray photoelectron spectroscopy and X-ray diffraction show that Ga elements accumulate on the surface of the liquid metal to form oxides, which significantly slowed the oxidation of the surface of the liquid alloy.

Effect Of 3% Molybdenum (Mo) Nanoparticles on The Melting, Microstructure and Hardness Properties of As- Reflowed Low Mass Sn-58Bi (SB) Solder Alloy

The Sn-58Bi (SB) lead free solder alloy tested in this research with addition of 3% Molybdenum (Mo) nanoparticles equivalent to 0.6g mass to analyse the influences in the thermal, microstructure and microhardness. Elevation of 3.8°C was observed from the Differential Scanning Calorimetry (DSC) for the 3% Mo nanoparticles added SB solder alloy compared to the bare Sn-58Bi (SB) solder alloy that has a melting temperature of 142.25°C. The microstructures of the reinforced SB solder alloy were refined with closer lamellar structures of ?-Sn and Bi phases compared to the unreinforced SB solder. The SEM/EDX and X-ray Diffraction (XRD) results validate the presence of the 3% Mo nanoparticles in the SB solder. Mechanical properties by means of Vickers microhardness of the Mo reinforced solder alloy showed an increment in hardness value by 2% compared to the bare SB solder alloy. The presence of 3% Mo as discrete particles (dispersion strengthening) contributes to the increase on the hardness value. The introduction of 3% Mo in to the SB solder alloy resulted in increase in the hardness due to the refinement of the microstructure and at the same time allows low temperature soldering in the electronic packaging industry.

Microstructure and mechanical properties of Sn–58Bi eutectic alloy with Cu/P addition

Sn–(58-x) Bi–x Cu/P ternary alloys were prepared by downward continuous casting, and the microstructure of the alloy was characterized using scanning electron microscopy (SEM), x-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The results show that the addition of Cu and P can refine the eutectic structure and form rod-shaped Cu6Sn5 and P3Sn4 phases distributed in Sn matrix. The refined eutectic structure can be observed in Sn–(58-x) Bi–x Cu/P alloys, and this results in the elongation at break increases up. In addition, the wettability of Sn–58Bi alloy increases on Cu substrate with the addition of Cu and P elements. The improvement of the wettability of Sn–58Bi alloy by the addition of Cu element can be attributed to the increase of Cu-Sn IMC nucleation and growth rate. The addition of P element in Sn–58Bi alloy can improve its anti-oxidation performance, which is beneficial to the improvement of its wettability.

Surface Properties of Indium, Tin, Bismuth, and Binary In–Bi and Sn–Bi Alloys

Surface Properties of Indium, Tin, Bismuth, and Binary In–Bi and Sn–Bi Alloys

Multicomponent Sn–Mo–O-containing films formed in anodic alumina matrixes by ionic layer deposition

Multicomponent metal oxide compounds of the composition Sn–Mo–O, Sn–Ni–Mo–O and Sn–Bi–Mo–O were formed by successive ionic layer adsorption and reaction (SILAR) method deposition into anodic alumina matrixes. The growth mechanism of the Sn–Mo–O-containing films in the porous anodic alumina was investigated. It was found that the degree of pore filling, specific thickness and surface morphology of the deposited layer depend not only on the number of cycle’s treatment, but also on the composition of the used solutions. The morphology of Sn–Mo–O and Sn–Ni–Mo–O surfaces had granular structures, while Sn–Bi–Mo–O layer had flake-like structure. The differences in microstructure and deposition of the layers on the surface of the matrixes can be explained by the insufficient activation of anodic alumina pores before deposition. The investigations of the formed layers composition by the electron-probe X-ray spectral microanalysis showed that the ratio of tin to molybdenum in tin-molybdenum containing oxides changes. The Sn/Mo atomic ratio for Sn–Mo–O layer is 1.29/2.72; for Sn–Ni–Mo–O layer is 5.83/4.85; for Sn–Bi–Mo–O layer is 0.60/0.87. The using of SILAR method allows forming multicomponent films in the anodic alumina matrixes, which have great potential to applicate in high-sensitivity gas sensors.

A general method to synthesize metal/N-doped carbon nanocomposites with advanced sodium storage properties

Seeking a general and facile method to prepare the nanocomposite of metal and carbon is the key to develop the metal-based anode in sodium ion battery. Here, a simple soft chemistry method followed by carbonization process is reported to prepare Bi(Sn)/N-doped carbon nanocomposites (denoted as Bi/NC and Sn/NC). The conductive carbon layer effectively hinders the volume effect during sodiation/desodiation process. Thus, Bi/NC and Sn/NC exhibit an outstanding rate capability of 220 and 158 mAh g−1 at 3.0 A g−1 and a long cyclic stability (negligible capacity fading after 2000 cycles for Bi/NC and 86.4% capacity retention after 1000 cycles for Sn/NC at 1.0 A g−1).

Enhancement of electrochemical and thermal bonding reliability by forming a Cu3Sn intermetallic compound using Cu and Sn–58Bi

Cu–Cu bonding was successfully achieved through the transient liquid phase sintering (TLPS) bonding method using Cu and an eutectic Sn–Bi alloy. The bonding process was performed for total bonding process time of 2 h under a pressureless condition in air. The bonding temperature was 220 °C considering that the Cu6Sn5 intermetallic compound (IMC) and Bi react at 195.9 °C to transform into Cu3Sn and a liquid. The shear strength of Cu-70(Sn–58Bi) was approximately 22.06 MPa with the formation of the Cu3Sn. The residual eutectic Sn–Bi structure remained at Cu-90(Sn–58Bi), and the voids were largely observed at Cu-50(Sn–58Bi). In case of Cu-70(Sn–58Bi) and Cu-50(Sn–58Bi), the remelting temperature increased to 270 °C by the IMC reaction between Cu and Sn. On the other hand, the remelting temperature of Cu-90(Sn–58Bi) joint remained at 139 °C due to residual eutectic Sn–Bi structure. The salt spray test was conducted at 35 °C under the 5% NaCl condition for 24, 48, and 96 h to evaluate the bonding reliability under the salt spray condition. The corrosion behavior was evaluated using the electrochemical impedance spectroscopy measuring method. In addition, the thermal bonding reliability was investigated through a high-temperature storage test at 200 °C for 100, 500, and 1000 h. Analysis results of the experiment showed that the electrochemical and thermal bonding reliabilities were improved with the Cu3Sn formation owing to its high resistance properties under the salt spray and high-temperature conditions.

Bi@Sn Core-Shell Structure with Compressive Strain Boosts the Electroreduction of CO2 into Formic Acid.

As a profitable product from CO2 electroreduction, HCOOH holds economic viability only when the selectivity is higher than 90% with current density (j) over −200.0 mA cm−2. Herein, Bi@Sn core–shell nanoparticles (Bi core and Sn shell, denoted as Bi@Sn NPs) are developed to boost the activity and selectivity of CO2 electroreduction into HCOOH. In an H‐cell system with 0.5 m KHCO3 as electrolyte, Bi@Sn NPs exhibit a Faradaic efficiency for HCOOH (FEHCOOH) of 91% with partial j for HCOOH (j HCOOH) of −31.0 mA cm−2 at −1.1 V versus reversible hydrogen electrode. The potential application of Bi@Sn NPs is testified via chronopotentiometric measurements in the flow‐cell system with 2.0 m KHCO3 electrolyte. Under this circumstance, Bi@Sn NPs achieve an FEHCOOH of 92% with an energy efficiency of 56% at steady‐state j of −250.0 mA cm−2. Theoretical studies indicate that the energy barrier of the potential‐limiting step for the formation of HCOOH is decreased owing to the compressive strain in the Sn shell, resulting in the enhanced catalytic performance.

Effects of Ni(P) layer thickness and Pd layer type in thin-Au/Pd/Ni(P) surface finishes on interfacial reactions and mechanical strength of Sn–58Bi solder joints during aging

To analyze the effects of Ni(P) layer thickness and Pd layer composition on interfacial reactions and the mechanical reliabilities of Sn–58Bi solder joints, we evaluated a phosphorous-contained Ni (Ni(P)) layer thicknesses ranging from 0.3 to 1.0 μm with Au/Pd/Ni(P) or a phosphorous-contained Pd [Au/Pd(P)/Ni(P)] layer in thin-electroless-nickel electroless-palladium immersion gold (ENEPIG) with Sn–58Bi solder joint after aging test. (Pd, Au)Sn4 and Ni3Sn4 intermetallic compounds (IMCs) were dominantly formed at the interfaces of the 0.3 µm to 1.0 μm Ni(P) layers in the thin-Au/Pd/Ni(P) or thin-Au/Pd(P)/Ni(P) joints after aging at 85 °C and 95 °C for 100 h. However, the Ni3Sn4 IMC layer changed to the (Cu, Ni)6Sn5 IMC layer in the 0.3 μm Ni(P) layer contained the Au/Pd/Ni(P) joint after aging at 85 °C for 300 h, because the Cu elements in a Cu pad penetrated through the P-rich Ni layer. Otherwise, the Ni3Sn4 IMC of the 0.3 μm Ni(P) layer in the Au/Pd(P)/Ni(P) joint changed to (Ni, Cu)3Sn4 IMC after aging at 105 °C and 115 °C for 1000 h, due to the P in the Pd layer, which affects the IMC growth rate. The 0.7 µm and 1.0 μm Ni(P) layers in the Au/Pd/Ni(P) or Au/Pd(P)/Ni(P) joints were attributed to the Ni3Sn4 IMC layer for whole aging conditions because the thick P-rich Ni layer suppress Sn and Cu diffusion during aging. In a high-speed shear tests, the shear strength of the 0.3 μm Ni(P) layer in the Au/Pd/Ni(P) joints was relatively low than that of the Au/Pd(P)/Ni(P) joints after aging at 105 °C and 115 °C for 100 h. Ni3Sn4 IMC was observed at the fracture surfaces of the 0.3 μm Ni(P) layer in the Au/Pd(P)/Ni(P) joints after aging at 115 °C for 1000 h, whereas the fracture surface of the Au/Pd/Ni(P) joint was Cu substrate. Therefore, Ni(P) layer thicknesses in excess of 0.7 μm and the P-contain Pd layer in the thin-ENEPIG surface finish with Sn–58Bi solder joints are expected to be highly reliable after long-term aging treatment.

High-temperature corrosion of Sn–Bi–Zn–Ga alloys as heat transfer fluid

The new heat transfer alloy is highly reactive at high temperatures, and the corrosion of the container material determines the service life of the heat transfer system. The high-temperature corrosion of Sn–Bi–Zn–Ga alloys as heat transfer fluid was investigated. The microstructure and elemental distribution were studied by field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS). The thermal properties before and after corrosion were studied by differential scanning calorimetry (DSC). The results show that the corrosion kinetics of the studied materials follows the parabolic law and the thermal properties after corrosion are improved. Ga significantly improves the thermal conductivity. 316 stainless steel exhibits excellent corrosion resistance due to its high Cr and Ni contents. Corrosion mechanism analysis shows that the oxidation of Ga has a smaller Gibbs free energy, and an oxide forms at the corrosion interface to prevent dissolution corrosion and oxidative corrosion of the container material.

Argillizite “Hats” of Kompleksnoe Ore Occurrence in Kayenmyvaam Volcanic Uplift (Central Chukotka)

The article is devoted to the results of mineralogical and geochemical studies of argillizites at Compleksnoe Au–Ag ore occurrence, localized on the southern flank of the Kajenmyvaam volcanic uplift in the inner zone of the Late Cretaceous marginal–continental Okhotsk-Chukchi volcanic belt (OChVB). At the ore occurrence, a series of isometric (oval) in plan view argillizite “hats” with diameters of 200 to 900 m are described. They are composed of red and light gray clay formations and accompanied by complex (Au–Ag–Mo–Cu–Pb–Zn–Bi–Sn) anomalies. In the recent relief, argillizite “hats” are characterized by gently sloping domes and crown subvolcanic bodies of granitoids and explosive breccias. A series of argillizite “hats” is surrounded by elongated lenticular bodies of secondary quartzites, which form the outer boundary of a large annular volcanostructure. The argillizites are composed of the following minerals: illite-smectite (mixed-layered formation), kaolinite, muscovite, jarosite, quartz, and rutile. The average content of Au and Ag in bulk samples are 0.06 and 0.075 g/t, respectively. Au is found in invisible form. According to the geological and geochemical data, argillizite “hats” record a near-surface (up to 300 m), slightly eroded, level of a large porphyry-epithermal mineral-forming system.

Nanoscale Visualization of Phase Transition in Melting of Sn-Bi Particles by In situ Hard X-ray Ptychographic Coherent Diffraction Imaging.

The phase transition in the melting of Sn–Bi eutectic solder alloy particles was observed by in situ hard X-ray ptychographic coherent diffraction imaging with a pin-point heating system. Ptychographic diffraction patterns of micrometer-sized Sn–Bi particles were collected at temperatures from room temperature to 540 K. The projection images of each particle were reconstructed at a spatial resolution of 25 nm, showing differences in the phase shifts due to two crystal phases in the Sn–Bi alloy system and the Sn/Bi oxides at the surface. By quantitatively evaluating the Bi content, it became clear that the nonuniformity of the composition of Sn and Bi at the single-particle level exists when the particles are synthesized by centrifugal atomization.