Bi Alloy Research Articles

Effects of Bi Alloying on the Thermoelectric Properties of p‐Type Mg3Sb2‐xBix Solid Solutions

AbstractBismuth is the most common alloying element for high‐performance Mg3Sb2‐based thermoelectric compounds. However, the electrical and thermal transport data is lacking for undoped Mg3(Sb, Bi)2 solid solutions. In this study, theoretical calculation results show that Bi alloying can reduce the band gap of Mg3Sb2, favoring the regulation of carrier concentration. Both Mg3Sb2 and Mg3SbBi compounds present a single band structure on the valence band maximum at Γ of the Brillouin zone. Incorporating the Bi element can slightly increase the density of states (DOS) on the valence band maximum, which is beneficial for the Seebeck coefficient. Mg3Sb2‐xBix (0≤x≤0.8) compounds were experimentally prepared via ball milling (BM) combined with the spark plasma sintering (SPS) technique. The carrier concentration, electrical conductivity, and power factor of the samples tend to increase with the increasing Bi content. Bismuth alloying significantly reduces the total thermal conductivity in the low‐temperature range, with the lowest value of 0.65 Wm−1K−1 obtained at ∼400 K for the x=0.2 sample. The peak ZT value of 0.077 at 800 K and the average ZT of 0.051 in the temperature range of 450–800 K are obtained for the x=0.2 sample, which is 93% and 219% higher than those of the unalloyed sample, respectively. This work reveals the Bi‐alloying induced transport mechanism and provides fundamental thermoelectric data regarding the undoped Mg3Sb2‐xBix (0≤x≤0.8) solid solutions.

Photoluminescence from InSb1−xBix alloys at extended wavelengths on InSb

The incorporation of dilute concentrations of bismuth into traditional III–V alloys produces significant reductions in bandgap energy presenting unique opportunities in strain and bandgap engineering. However, the disparity between the ideal growth conditions for the host matrix and those required for substitutional bismuth incorporation has caused the material quality of these III–V–Bi alloys to lag behind that of conventional III–V semiconductors. InSb1−xBix, while experimentally underexplored, is a promising candidate for high-quality III–V–Bi alloys due to the relatively similar ideal growth temperatures for InSb and III–Bi materials. By identifying a highly kinetically limited growth regime, we demonstrate the growth of high-quality InSb1−xBix by molecular beam epitaxy. X-ray diffraction and Rutherford backscattering spectrometry (RBS) measurements of the alloy's bismuth concentration, coupled with smooth surface morphologies as measured by atomic force microscopy, suggest unity-sticking bismuth incorporation for a range of bismuth concentrations from 0.8% to 1.5% as measured by RBS. In addition, the first photoluminescence was observed from InSb1−xBix and demonstrated wavelength extension up to 7.6 μm at 230 K, with a bismuth-induced bandgap reduction of ∼29 meV/% Bi. Furthermore, we report the temperature dependence of the bandgap of InSb1−xBix and observed behavior consistent with that of a traditional III–V alloy. The results presented highlight the potential of InSb1−xBix as an alternative emerging candidate for accessing the longwave-infrared.

Investigations of wear properties of immiscible monotectic Al-10Bi alloy

ABSTRACT This study focused on improving the wear properties of a monotectic Al-10%Bi alloy. The properties of the alloy were improved through two different processes. The effect of artificial ageing and addition of Mn in alloys was investigated. The alloys are produced in an atmosphere-controlled mini-arc furnace. The first sample of the alloy (AlBi-aged) was artificially aged. In order to make the alloy suitable for ageing, 1% Mg and 0.5% Si elements were added to the alloys. The AlBi-aged sample was kept at 525°C for 2 h for artificial ageing and quenched in ice water. The samples were then aged at 180°C for a total of 72 h. In the second sample, 3 wt% Mn (AlBi3Mn) was added to the alloy. Samples containing 3% Mn were examined directly (without ageing). Finally, the alloys were tested for dry wear by reciprocating motion. XRF and XRD analyses were applied to all samples. SEM and EDX analyses were performed for morphological analysis. The samples were also taken to the microhardness test. As a result, the wear resistance of the sample, which was artificially aged for 24 h, increased by 34%. In the AlBi3Mn sample, the hardness increased approximately two times, while the wear resistance increased by 67%.

Understanding solidification and wear behaviour of Al-3Cu-Bi alloys

Considering that Bi is able to decrease friction between contacting surfaces, wear damage is expected to decrease as well. Bi-containing Al alloys have emerged as a choice for creating self-lubricating parts. The current work compares the effects of two distinct Bi alloy contents on the microstructure, Bi morphology/spacing, hardness, and wear resistance of Al-3.0wt.%Cu-Bi alloys. The novelty is in determining the microstructure constituting the Al-Cu based alloys with different Bi additions. Also, functional relationships between the wear resistance and the Bi droplets are derived. Increasing the Bi content from 2.0 to 3.2 wt.% changed the size and spacing of Bi particles as well as decreased hardness and increased the wear resistance. Even though the Al-3.0wt%Cu-3.2wt%Bi alloy has a lower hardness, the greater Bi fraction seems to be the key factor enhancing wear resistance. The bigger Bi areas spreading over the Al-rich phase under wear allowed higher wear resistance.

In-Situ Derived Bi Alloys for High Performance and High Power Li-Ion Batteries: Effects of Conversion Family, Mesomatrix, and Electrolyte

Despite the fact that the first commercial rechargeable Li battery was based on a Li-Al alloy in the 1970s, extensive investigation of Li alloys for next generation high performance Li-ion batteries has taken place only since Fuji’s initiation of the renaissance in the 1990s [1-2]. Although the majority of this research has been directed towards Si, Sn, Ge and Al [3-4], Bi possesses interesting properties that make it unique amongst the lithium alloys. The heavy pnictogen is of relatively low toxicity with a broad range of applications from Pb replacement in solders to formulations in antacids. In spite of its high molecular weight LixBi exhibits very high volumetric capacity and exceptional Li+ diffusion in its second lithiated phase, Li3Bi [5]. The 0.8 V alloying potential of Bi vs Li/Li+ allows for a more advantageous selection of electrolyte salts and solvents than the aforementioned Si, Ge, and Al. Coupled with its superionic Li+ diffusivity, the higher alloying potential of Bi also provides a larger safety window against Li plating from overpotentials and enables fast charge. While the considerable volume expansion of Bi impedes sustained capacity retention—as with all other Li alloy metals—the volume change from complete lithiation is significantly smaller than that of the popular Si: 108% for Li3Bi compared to 208% for Li13Si4 at a comparable 3.25 Li+ insertion. Combined, these positive attributes present the opportunity to meet the high-rate and volumetric energy capability needs in the next generation of Li-ion batteries.In this work, we explore the effectiveness of BiF3 as an electrochemical precursor to generating a Bi nanocomposite with excellent cycling efficiency extending beyond 250 cycles. An understanding of the nanocomposite’s effectiveness is derived from observations of Bi crystallite sizes produced from the conversion of BiF3, Bi2O3, and Bi2S3. Through electrochemical and physical characterization of these conversion materials, the size of the post-conversion Bi product was found to be not a result of processing conditions but rather the choice of conversion material. The resulting Bi crystallite size post-conversion shows a correlation between the in-situ derived crystallite size and the ionic conductivity of the resulting Li salt matrix. The resulting Bi crystallite size also provides evidence for the inverse relationship between the in-situ derived crystallite size and cyclability that is consistent with theory. For further development, alternative matrices to C were explored in order to preserve the high volumetric capacity of LixBi. Metal sulfides proved a more effective and volumetrically efficient C substitute, with the former exhibiting gravimetric capacities comparable to the latter. Electrolyte formulations derived from use in Bi/C nanocomposites were also tested and proved effective in stabilization of the Li–Bi alloying mechanism in our BiF3 compositions for further cycling improvements. Finally, we demonstrate the ability of BiF3-derived LixBi alloy thin films to delithiate with an 80% utilization at >100C rate despite the presence of a LiF nanomatrix.Through the development of BiF3 nanocomposites using carbon or sulfide matrices in conjunction with an alloy-specific optimized electrolyte, we are able to demonstrate the exceptional cycling of the LixBi alloy (Fig. 1 a,b black) relative to using pure Bi metal in a composite (Fig. 1a,b blue). This presentation will outline the optimization of this alloy family from a holistic perspective and discuss future pathways based on the foundations established here, inclusive of the minimization of the LiF matrix, and in context with the other relatively few publications on this interesting alloy [6-9].

Optimization of mechanical properties of Sn-3.8Ag-0.7Cu alloys by the additions of Bi, In and Ti

Bi, In and Ti were added to Sn-3.8Ag-0.7Cu (SAC387) solder alloy to optimize the mechanical performance. The alloying effects of Bi, In and Ti on the microstructure, thermal and mechanical properties of SAC387 based solder alloys were investigated. The results demonstrate that adding 3.5 ​wt % of Bi could refine the microstructure, optimize the thermal properties, and improve the tensile strength. Meanwhile, the ductility of the solder alloys reduced evidently. Adding 2.8 ​wt % of In into SAC387–3.5 ​wt %Bi alloy could increase both the strength and ductility, which is attributed to the beneficial effect of In addition, as adding In could improve the solubility of Bi in the β-Sn matrix. Meanwhile, the melting point was reduced, and the wettability improved with the addition of In. Introducing amounts of Ti into SAC387–3.5 ​wt % Bi-2.8 ​wt % In alloy could further increase the strength. However, the ductility was significantly reduced when 0.8 ​wt % of Ti was added due to the formation of the coarse Ti2Sn3 phase. The undercooling was remarkably reduced with the addition of Ti. The nanoindentation tests demonstrate that the hardness increased mainly due to the hardening effect of the Bi addition. Among all the samples prepared, alloy SAC387–3.5 ​wt % Bi exhibited the highest creep resistance at the ambient temperature. Further adding In and Ti into SAC387–3.5 ​wt % Bi alloys reduced the creep resistance of the solder alloys. The mechanism associated with the different mechanical responses is also discussed in this study.

Deformable Triphase Tin-Aluminium-Bismuth Anodes for Rechargeable Magnesium Ion Batteries

Sn-based anodes for magnesium ion batteries (MIBs) arouse considerable interests, but are restrained by severe failure associated with poor electrochemical reactivity and massive volume changes during cycling. Herein, a multiphase alloying strategy is proposed to improve the electrochemical performance of Sn-based anodes through introducing an active Bi phase and an inactive Al phase to trigger the alloying reaction of Sn with Mg and accommodate large volume variations. A series of triphase Sn–Al–Bi alloys with different compositions were fabricated via a melting-solidification method. The significant performance improvement of the triphase Sn–Al–Bi electrodes stems from the interdigitated phase distribution accelerating Mg2+ ions transport and the multiphase buffering matrix alleviating the structural damage during cycling. Specially, the Sn55Al40Bi5 electrode exhibits attractive deformation capability, moderate areal specific capacity and long-term cycling stability up to 1000 cycles. Additionally, operando X-ray diffraction was performed to unveil the magnesiation/demagnesiation mechanisms of the Sn-Al-Bi electrodes. Noticeably, the Sn-Al-Bi electrodes show good compatibility with simple Mg salt electrolytes such as Mg(TFSI)2 in a full cell.

First-principles investigation of mechanical properties, elastic anisotropy, and ultralow lattice thermal conductivities of ductile Mg–Bi alloys

The crystal structures, mechanical properties, anisotropic properties, and lattice thermal conductivities of Mg–Bi alloys have been investigated by particle swarm optimization structure prediction method and first-principles calculations. Apart from the well-known stoichiometry of Mg3Bi2, the novel stable stoichiometry of Mg4Bi, as well as several metastable stoichiometries (i.e., Mg3Bi, Mg2Bi, and MgBi) are predicted. Meanwhile, the calculated phonon dispersion curves and elastic constants show that the above five Mg–Bi alloys are dynamically and mechanically stable, respectively. Moreover, the calculated mechanical properties indicate that the studied Mg–Bi alloys with various stoichiometries behave ductility. Simultaneously, they exhibit obvious anisotropic characters and the degree of anisotropy follows the order of MgBi > Mg2Bi > Mg3Bi > Mg4Bi > Mg3Bi2. More importantly, the minimum lattice thermal conductivities of MgBi and Mg2Bi are smaller than that of the well-known Mg3Bi2. The adsorption of O atom on the Mg3Bi (001) surface is more sensitive compared with other four Mg–Bi (001) surfaces.

Exploring the formation of InAs(Bi)/GaAs QDs at two growth-temperature regimes under different Bi supply conditions

The effect of a Bi supply on the development of InAs/GaAs (001) QDs has been structurally explored in two growth temperature regimes, one for Bi alloying (380 °C) and another for conventional formation of InAs QDs (510 °C). At high growth temperature (HT), there is no trace of Bi incorporation into the film and Bi acts as a surfactant limiting the diffusion length of In. All HT QDs are coherent and free of defects with an inverted cone-shaped In distribution. Increasing the Bi supply increases both the QD size and the In content (up to 40 %), while decreasing their areal density. At low temperature (LT), the addition of Bi goes beyond the surfactant role, promoting the transformation of the growth mode from 2D to 3D, resulting in an exponential increase in the QD size with Bi supply. Based on size, these LT QDs are divided into two populations in which the larger QDs relax plastically through the formation of misfit dislocations. LT QDs grown under a Bi flux reach a higher In content (80 %) with a homogeneous distribution within them. Remarkably, incorporation of Bi into larger QDs has been detected but it is not homogeneously distributed.

In Situ Derived Bi Alloys for High-Performance Li-Ion Batteries: Effect of Conversion Chemistry, Mesomatrix, and Electrolyte

LixBi alloys are a unique path to enable extraordinarily high rate, safer, and high volumetric energy density batteries. The effectiveness of BiF3 as an electrochemical precursor to a LixBi nanocomposite with excellent cycling efficiency extending beyond 250 cycles is explored to identify key factors critical to future successful development. The relationships between the converted crystallite size and subsequent electrochemical properties were reported with a specific focus on cycling efficiency. Through electrochemical and physical characterization of post-converted BiF3, Bi2O3, and Bi2S3, the size of the post-conversion Bi product was directly correlated with the ionic conductivity of the in situ formed Li salt matrix and subsequent cycling stability. Further key areas for development were introduced, including volumetrically dense conductive alternatives to C and electrolyte formulations, which demonstrate significant improvements in cycling stability. In addition, we demonstrate the ability of BiF3-derived LixBi alloy thin films to delithiate with an 80% utilization at >100 C rate despite the presence of a LiF nanomatrix.

High Air Stability and Excellent Li Metal Compatibility of Argyrodite‐Based Electrolyte Enabling Superior All‐Solid‐State Li Metal Batteries

AbstractSulfide solid electrolytes (SSEs) for all‐solid‐state Li metal batteries (ASSLMBs) are attracting increasing attention due to their ultrahigh ionic conductivity and good machinability. However, current SSEs generally suffer from inferior Li metal compatibility and poor air‐stability, which severely impede their practical applications for ASSLMBs. Herein, novel argyrodite‐based SSEs of Li6+2xP1−xBixS5−1.5xO1.5xCl are synthesized via the Bi, O co‐doping the Li6PS5Cl for the first time. By adjusting the concentrations of dopant, the optimized Li6.04P0.98Bi0.02S4.97O0.03Cl presents an ultrahigh ionic conductivity (3.4 × 10−3 S cm−1). Moreover, such electrolyte displays splendid structural stability after exposure to humid air and chlorobenzene, demonstrating admirable air‐stability and solvent‐stability. The mechanism of the enhanced air‐stability of oxide‐doped SSEs is profoundly understood by conducting first‐principles density functional theory calculations. In addition, the Li6.04P0.98Bi0.02S4.97O0.03Cl electrolyte triggers the generation of LiBi alloy at the anode interface, which plays a crucial role in reducing Li+ diffusion energy barriers and improving interfacial compatibility, leading to an ultrahigh critical current density of 1.1 mA cm−2 and splendid cyclic stability in Li symmetric cell. As a result, ASSLMBs equipped with either pristine or air‐exposed Li6.04P0.98Bi0.02S4.97O0.03Cl can deliver satisfying discharge specific capacity at room temperature.

Combining electrolysis with thermocatalysis for dry reforming of methane in a naturally stratifying liquid alloy-salt catalytic system

Dry reforming of methane (CH4) with carbon dioxide (CO2) is an attractive technology for producing value-added syngas and mitigating greenhouse gas emission. However, this process usually requires high energy input due to the intrinsic inertness of CH4 and CO2. Besides, the widely investigated solid Ni-based catalysts typically suffer from coking and sintering issues, leading to degradation in catalytic performance. Liquid alloys and molten salts are emerging as promising catalytic materials for CH4 dry reforming. In this work, we combine electrolysis with thermocatalysis for CH4 dry reforming in a naturally stratifying liquid alloy-salt system, which achieves effective and stable catalytic performance under relatively mild operation conditions. The conversions of CH4 and CO2 reach 37% and 95%, respectively, in a bubble column reactor comprising Ni–Bi alloy and LiNaCO3 during constant current electrolysis at 1.5 A and 900 °C. The selectivities of H2 and CO were maintained at 85% and 92%, respectively. Ab initio molecular dynamics simulation shows that the oxides of both Ni and Bi promote the C–H bond dissociation. Therefore, the electrochemical process combine electrolysis with thermocatalysis in the liquid alloy-salt system represents a promising approach to achieving effective and stable CH4 dry reforming.

Oxygen reduction reaction on PdM/C (M = Pb, Sn, Bi) alloy nanocatalysts

In this work three PdM/C bimetallic catalysts were prepared with a second metal being either Bi, Pb or Sn. The synthesised Pd-alloy nanoparticles were supported on Vulcan carbon XC-72R. These catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM) and electrochemically using the rotating disk electrode (RDE) technique. The prepared Pd-based electrocatalysts were compared to pure Pd/C catalyst synthesised using the citrate method. The oxygen reduction reaction (ORR) kinetics on Pd-alloy catalysts in alkaline solution was systematically investigated. Pd content was determined by microwave plasma atomic emission spectroscopy, which was used to calculate the mass activities (MA) for ORR. Mass activities revealed that BiPd had two-fold higher and PbPd showed 1.6-times increase in MA as compared to Pd/C, however SnPd showed lower MA than Pd/C. BiPd/C catalyst showed around 45% increase in specific activity (SA) for ORR, PdSn catalyst showed around 25% increase and PbPd no increase in SA in comparison to the Pd/C catalyst. Methanol tolerance was also studied for the PdM/C alloy catalysts and a higher tolerance was observed for BiPd/C losing 17 mV in the half-wave potential value and even better methanol tolerance was in evidence with the other two catalysts that lost only ∼10 mV in 0.1 M KOH + 0.5 M MeOH.

Investigation into the Performance of NiTi Shape Memory Alloy Wire Reinforced Sn-Bi Self-Healing Metal Matrix Composite.

Self-healing materials have the potential to create a paradigm shift in the life cycle design of engineered structures, by changing the relation between material damage and structural failure, affecting structures’ lifetime, safety, and reliability. However, the knowledge of self-healing capabilities in metallic materials is still in its infancy compared to other material systems because of challenges in the synthesis of organized and complex structures. This paper presents a study of a metal matrix composite system that was synthesized with an off-eutectic Tin (Sn)-Bismuth (Bi) alloy matrix, reinforced with Nickel–Titanium (NiTi) shape memory alloy (SMA) wires. The ability to close cracks, recover bulk geometry, and regenerate strength upon the application of heat was investigated. NiTi wires were etched and coated in flux before being incorporated into the matrix to prevent disbonding with the matrix. Samples were subjected to large deformations in a three-point bending setup. Subsequent thermo-mechanical testing of the composites confirmed the materials’ ability to restore their geometry and recover strength, without using any consumable components. Self-healing was accomplished through a combination of activation of the shape memory effect in the NiTi to recover the samples’ original macroscopic geometry, closing cracks, and melting of the eutectic material in the matrix alloy, which resealed the cracks. Subsequent testing indicated a 92% strength recovery.

Toward dendrite-free and anti-corrosion Zn anodes by regulating a bismuth-based energizer

Aqueous rechargeable zinc metal batteries display high theoretical capacity along with economical effectiveness, environmental benignity and high safety. However, dendritic growth and chemical corrosion at the Zn anodes limit their widespread applications. Here, we construct a Zn/Bi electrode via in-situ growth of a Bi-based energizer upon Zn metal surface using a replacement reaction. Experimental and theoretical calculations reveal that the Bi-based energizer composed of metallic Bi and ZnBi alloy contributes to Zn plating/stripping due to strong adsorption energy and fast ion transport rates. The resultant Zn/Bi electrode not only circumvents Zn dendrite growth but also improves Zn anode anti-corrosion performance. Specifically, the corrosion current of the Zn/Bi electrode is reduced by 90% compared to bare Zn. Impressively, an ultra-low overpotential of 12 ​mV and stable cycling for 4000 ​h are achieved in a Zn/Bi symmetric cell. A Zn–Cu/Bi asymmetric cell displays a cycle life of 1000 cycles, with an average Coulombic efficiency as high as 99.6%. In addition, an assembled Zn/Bi-activated carbon hybrid capacitor exhibits a stable life of more than 50,000 cycles, an energy density of 64 ​Wh kg−1, and a power density of 7 ​kW ​kg−1. The capacity retention rate of a Zn/Bi–MnO2 full cell is improved by over 150% compared to a Zn–MnO2 cell without the Bi-based energizer. Our findings open a new arena for the industrialization of Zn metal batteries for large-scale energy storage applications.

Solvent-free, efficient synthesis of methyl phenyl carbonate over an SBA-15 loaded Pb–Bi bimetallic catalyst

Methyl phenyl carbonate (MPC) is one of the versatile carbonates; in particular, it is an important component in lithium-ion batteries. In recent years, the catalytic synthesis of MPC has become an important topic, but the development of highly active catalysts is still challenging. In this study, SBA-15-loaded nano-sized Pb–Bi catalysts with different Pb/Bi molar ratios were prepared by deposition–precipitation to improve the efficiency and selectivity. To investigate the relationship between the structure and performance of the catalysts, XRD, BET, SEM-EDS, HRTEM, H 2 -TPR, and XPS characterization, as well as catalytic activity and stability tests, were conducted. Results revealed that Pb–Bi/SBA-15 can efficiently catalyze the synthesis of MPC under solvent-free conditions, with the highest catalytic activity obtained over 6 Pb–1Bi/SBA-15. SBA-15 with a large pore size and a high specific surface area was suitable as catalyst carrier, and the average diameter of Pb–Bi oxide particles was ∼3.57 nm. The addition of Bi led to the improved dispersion of active components, which were highly and evenly dispersed on the SBA-15 surface. Furthermore, an appropriate proportion of Pb and Bi on SBA-15 was conducive to the considerable enhancement of the catalytic activity. Besides, Pb–Bi/SBA-15 also exhibited good durability and recyclability, making it a promising catalytic material for the synthesis of various carbonates. SBA-15-loaded nano-sized Pb–Bi catalysts were synthesized by a deposition-precipitation method, which can efficiently catalyze the synthesis of MPC without the use of a solvent. The 6 Pb–1Bi/SBA-15 catalyst exhibited the highest catalytic activity as well as superior stability and recyclability. • Efficient synthesis of methyl phenyl carbonate was performed using a Pb–Bi bimetallic catalyst. • Methyl phenyl carbonate was obtained in high yield and selectivity without solvent. • Formation of a highly dispersed Pb–Bi alloy on the catalyst surface was verified. • A facile catalytic approach for efficient synthesis of various organic carbonates was presented.

Large-Scale Test Facility for Modeling Bubble Behavior and Liquid Metal Two-Phase Flows in a Steel Ladle

Abstract A new experimental facility has been designed and constructed which represents a 1:5.25 model of an industrial 185 t steel ladle. This setup is intended for systematic investigations of complex liquid metal multiphase flows created by gas blowing from the bottom. Two tons of a Sn-40 wt pct Bi alloy are employed as working fluid, its thermophysical properties are very similar to those of liquid steel. The relatively low operating temperatures (T ~ 200 °C) compared to the real industrial process allow the use of powerful measuring techniques for characterizing the behavior of the gas phase and resulting flow regimes. Argon gas is injected through diverse plug systems into a cylindrical fluid vessel which is equipped with a pressure tight lid to achieve low-pressure conditions for vacuum processing. This paper presents first measurements of the gas distribution close to the free liquid metal surface for various gas flow rates, plug positions and types. Moreover, the pressure in the vessel has been varied between 1 mbar and ambient pressure. The experiments provide a copious data base about flow regimes, void fraction, liquid and bubble velocities, and bubble properties, which can be used to provide so far unknown boundary conditions for numerical simulations of various metallurgical reactors such as steelmaking converters or steelmaking ladles.

Comprehensive study on structure, mechanical and nuclear shielding properties of lead free Sn–Zn–Bi alloys as a powerful radiation and neutron shielding material

Various compositions of 60Sn- (40-x) Zn – xBi (where x = 0, 10, 20, 30, 40 wt%) rapidly solidified alloys have been prepared by melt-spinning technique. The structural and mechanical properties have been investigated by X-ray diffraction (XRD) and tensile test machine techniques respectively. Additionally, the nuclear shielding performance of the prepared alloys was examined. XCOM software was used to compute the μm values across a large energy range of 0.015 MeV–15 MeV. To clearly comprehend the radiation and neutron shielding capabilities of the prepared alloys, various parameters such as mass attenuation coefficient (μm), half value layer (HVL), total atomic (σa) and total electronic cross-sections (σe), effective atomic number (Zeff), exposure buildup factor (EBF), energy absorption buildup factors (EABF), specific absorbed fraction of energy (SAFE) and macroscopic effective removal cross section (ΣR) were computed and compared to other commonly shielding materials. The results revealed that increasing Bi content leading to decreasing the crystal size which enhances the mechanical and radiation shielding properties. The Sn-40% Bi (S5) alloy shows a maximum increase of the Young's modulus value of 90.5 GPa, the tensile strength of 299.9 MPa, yield strength of 267.9 MPa, μm, Zeff, and ΣR of 0.1016 cm−1. The results also show that, HVL, MFP, EBF, EABF and SAFE values are all lowest in the S5 alloy. As a result, the S5 alloy may be regarded a preferable material for radiation shielding applications. The findings of this research might be very beneficial in the future for nuclear waste storage, medical and industrial uses.

Influence of Second Phase Particles on Thermal Conductivity of Bi Alloys

High-Bi alloys are being explored to understand their potential as replacement for high-Pb alloys in high-temperature die-attach applications. Thermal conductivity of these alloys is an important consideration for die-attach applications, where heat dissipation is necessary for reliable operation of the devices. Pure Bi has a thermal conductivity of about 8 W/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\cdot \text{K}$ </tex-math></inline-formula> , which is the lowest among metals. The addition of the alloying elements to Bi had been explored to tailor its thermal, mechanical, and other physical properties. In this study, the role of Cu and Sb on the effective thermal conductivity of the resultant alloys was investigated. The thermal conductivities of these alloys in the bulk form and the three-layer die-attach form were measured using a flash diffusivity technique. Test specimens were developed to replicate a die-attach assembly between the Ni-metallized Si die and Cu substrate using the Bi– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x$ </tex-math></inline-formula> Sb–10Cu alloy (where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x =10$ </tex-math></inline-formula> –20 wt%). The three-layered structure was modeled with the unknown diffusivity of an intermediate layer of the Bi alloy. The alloy microstructure comprises a composite of Bi–Sb solid solution filled with Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Sb intermetallic particles. The presence of these intermetallic phases is responsible for an effective increase in thermal conductivity of this alloy. With the optimized microstructure developed, the resultant thermal conductivity was obtained at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 24$ </tex-math></inline-formula> W/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}\cdot \text{K}$ </tex-math></inline-formula> , which is a threefold increase compared to pure Bi.

Superior electrochemical performance of Sb–Bi alloy for sodium storage: Understanding from alloying element effects and new cause of capacity attenuation

Sb–Bi alloy has attracted increased attention as anode material for sodium-ion batteries (SIBs) owing to its particular crystal structure relevance and synergy effect. However, the cycle performance and actual capacity of Sb–Bi alloy are still not satisfactory, and the mysteries about partial role of elemental compositions and causes of capacity attenuation remain unsolved either. Herein, 3D Sb–Bi alloy/N-doped porous carbons (N–PCs) with different Sb/Bi mole ratios have been synthesized successfully. As for SIB anodes, 3D Bi3Sb1/N-PC presents a superior rate capability up to 30 A g−1 (specific capacity: 318.3 mAh g−1) and cyclic stability (capacity decays: 0.0054% per cycle at 10 A g−1 after 6000 cycles). Furthermore, the dissolution behavior of metallic Sb can be found after long-term cycles with DME-based electrolyte, and the dissolved Sb can shuttle to the other side of the separators, leading to “dead antimony” with low specific capacity and unsatisfactory cycle performance. Notably, Bi crystal shows strong fixing effect on Sb atoms with low loss of “active antimony”. Our work presents a great potential of alloy-type anode materials for practical applications of high-energy SIBs, and also provide a new direction to analyze element roles and attenuation causes of Sb–Bi alloys for sodium storage.