Sn Phase Research Articles

ELECTROCHEMICAL CORROSION EVALUATION OF SnSb ELECTRODEPOSITED COATINGS

SnxSb(1−x) coatings were electrodeposited from 1ChCl:2EG on copper. The corrosion resistance of the electrodeposits was evaluated in 0.1 mol dm-3 of NaCl. The characterization was performed by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Voltammetric profiles showed that the electrodeposition potential shifted towards less positive values with increasing Sb3+ concentration. SEM images revealed that the coatings exhibited grains and clusters. EDS analyses showed that the Sb content increased with the Sb3+ concentration. XRD results indicated the formation of the SbSn phases such as Cu2Sb, Cu6Sn5, and Cu6(Sn,Sb)5. The potentiodynamic polarization (PP) curves showed that Sn and Sn77Sb23 presented a passive potential region, while Sn37Sb63 had an active dissolution in the electrolyte. Immersion tests were performed for 24 h and XRD results revealed Cu, Sn, SnO, SbSn and Sb2O4 phases. Considering 48 h, Cu, CuSn, SnO2 and SnSb phases were identified. The polarization resistance values of 4.60, 14.69 and 1.81 kΩ cm2 were achieved for Sn, Sn77Sb23, and Sn37Sb63, respectively. The EIS results suggested that adding Sb3+ improves corrosion resistance for SnSb samples with higher Sn content. For Sn77Sb23, the charge transfer resistance was 10.5 kΩ cm2, for Sn and Sn37Sb63 1.15 and 1.46 kΩ cm2, respectively.

Hydrothermally Synthesized SnS2 Anode Materials with Selectively Tuned Crystallinity as an Asset for Self-Healing Property and One Step in Situ Solid State Carbonization and Synthesis of C-SnS2

Tin-based chalcogenides such as SnS2 have been investigated as potential anode active materials for Li-ion batteries due to their high theoretical reversible capacities (e.g., 644 mAhg-1 for SnS2). These high capacities are associated with the reversible alloying of Sn with Li after the conversion reaction of SnS2 to Sn and Li2S. In this work, SnS2 was prepared via two approaches: hydrothermal synthesis of SnS2 and one step solid state synthesis of carbon coated SnS2. In the hydrothermal reaction, different molar ratios of tin chloride to thioacetamide were employed to synthesize SnS2 nanocrystals with varying fractions of the crystalline and amorphous states. An increase in molar ratio showed more crystalline SnS2 products with intensified different crystal plane orientations and formation of monolayers on the surface grains. During electrochemical analysis vs Li/Li+, partial reversibility of Sn and Li2S back to SnS2 was observed, leading to a unique self-regeneration property of the electrode. The presence of nano crystals and their level of crystallinity was examined by ex-situ Transmission Electron Microscopy (TEM) and X-ray Diffraction analysis (XRD). Galvanostatic Intermittent Titration (GITT) with in-situ Electrochemical Impedance Spectroscopy (EIS) after each galvanostatic step was used to evaluate the lithium diffusion coefficients (DLi+) to elucidate the lithium intercalation kinetics of SnS2 and its conversion to Sn and Li2S phases up to x ≈ 2.08 moles of lithiation or 300 mAh g-1. The SnS2 anode samples showed good cycling stability across 100 cycles at 0.1 C rate (560 mAh g-1) in half cell testing against Li chip. In full cell mode against NCM 811 cathodes, the cell retained a specific capacity of 160 mAh g-1 at 300th cycle.Further, we introduce a low cost, scalable solid state heat treatment method to produce SnS2-C materials, where the carbon not only facilitates electron transport, but also assists to mitigate the volume expansion of SnS2 during lithiation and enhance its structural stability. However, due to the phase transformations of SnS2 during heating, SnS2-C materials cannot be synthesized via solid state heat treatments of SnS2 with a carbon source. However, in this work, we show a novel method of producing carbon-coated SnS2 by thermally treating Sn-precursors and S with organic polymers. Using this method, SnS2-C materials were prepared, where the SnS2 crystal structure was retained and no impurity tin-sulfides such as SnS and Sn2S3 were formed. The electrochemical performance of the SnS2-C anode active materials was tested vs Li/Li+ and excellent cycling stability can be reported when compared to non-coated SnS2.Keywords: SnS2, anodes, composite anodes, carbon coating. Acknowledgement This research work is funded by Project “RESTINA”, where the main goal is to deliver “generation 3b cells for battery electric vehicles (BEVs)”. Funding agentM-ERA.NET has defined 6 quantified priorities, both in terms of their objectives and their budgetary impact: 1) support basic research in all scientific fields, 2) intensify the strategic research, 3) amplify the international dimension, 4) develop interdisciplinary research, 5) encourage "risky" projects and 6) establish equipment and infrastructure at the service of fundamental research and innovation. Figure 1

Thermo-mechanical response and form-stability of a fully metallic composite phase change material: Dilatometric tests and finite element analysis

Composite Phase Change Materials (C-PCMs), such as immiscible Al-Sn alloys are designed to store and release heat as a result of the phase transformation of one of the phases, i.e., Sn in this case. The volume changes induced by melting and solidification of the low-melting Sn phase as well as the different thermal expansion of solid Al and Sn phases induces stress fields during thermal cycles. Repeated experimental dilatometric tests were performed on the above C-PCM to check their microstructural stability as well as its effect on their form-stability, i.e., capability to recover the initial shape under various potential cyclic service conditions.Analysis of the thermo-mechanical behaviour of the two phases, as well as the overall one, have been investigated under the simple thermal profiles reproducing dilatometric tests. A finite element model of fully dense Al-Sn C-PCM, where a single spherical inclusion of Sn is surrounded by Al matrix, is generated and numerical thermo-mechanical analysis is performed. The thermal-dependence of elastoplastic-behaviour, thermal expansivity and other thermophysical properties of the 2 solid phases has been modelled, together with compressibility of liquid Sn. The simulations illustrate the overall material behaviour as well as the local thermomechanical response. The results for the slopes of elongation vs temperature curves agree well with experimental data from dilatometric tests, for which form-stability is observed from the third cycle. The results also suggested that the plastic deformation of the only regions of Al phase surrounding the Sn inclusion accommodates its expansion during heating and melting. In these latter regions, at the end of a dilatometric cycle, compressive strain in radial direction reaches a maximum value of 0.1 %, higher than overall strains.

Tribological behavior of AlSn20Cu alloy manufactured by additive friction stir deposition

Al-Sn alloy is utilized as a bearing material to replace conventional Sn-based alloy in the design of bearing liners due to its higher load-carrying capacity and wear resistance. However, cracks readily initiate in casting Al-Sn alloy near the coarse Sn phase, leading to low mechanical properties and insufficient wear resistance. The present study introduces a new method, additive friction stir deposition (AFSD), to produce AlSn20Cu alloy with fine grains and sub-micron-scale Sn phases, resulting in enhanced mechanical performance and wear resistance. Compared to both casting and cold rolling + annealing AlSn20Cu alloys, the ultimate tensile strength of AFSD AlSn20Cu alloy is improved by 80.56 % and 16.67 % respectively. Additionally, AFSD AlSn20Cu alloy demonstrates a lower coefficient of friction (COF) and lower wear rate without significant subsurface damage. This is attributed to the fine and uniformly distributed Sn phase forming a uniform and dense surface lubrication layer that adapts the friction pair to the boundary lubrication state, preventing the initiation and development of cracks.

Microstructure of ternary Sn-Bi-xCu alloy on mechanical properties, current endurance and corrosion morphology via cycling corrosion test

Low melting temperature of Sn-58 wt% Bi (SB) solders adding 0.5 wt% Cu (SB05C) and 1.7 wt% Cu (SB17C) concentrations were evaluated for the signal transmission in the 3D IC package. Microstructure combined with phase analysis and Pandat simulation were together with to explain the relationship among the mechanical property, electrical endurance and corrosion resistance. By Cu decoration, the presence Cu6Sn5 intermetallic compound (IMC) acts as heterogeneous nucleation sites to reduce surface free energy and generate fine Bi grain that resulted in higher hardness value. The power-law was used to explain the mechanism of interfacial IMC growth, both Cu6Sn5 and Cu3Sn formation were speculated to be volume diffusion control and surface reaction domination, respectively. The fracture morphology by shear testing indicates that earliest plastic deformation accompanied with brittle rupture were major factors due to the intergranular fracture and Cu6Sn5 compound induced bulk fracture. By cycling corrosion test (CCT), the lump shape of SnO2 by-product was found among solders at three cycling. After seven cycling, Sn phase has been completely corroded and Cu6Sn5 IMC began to be corroded forming circle shape of Cu2O but Bi phase still not be corroded among solders. In the electrical endurance, dense Cu6Sn5 dispersed in solder bulk and fine grain size were feasible to induce current crowding and joule heating, thus Cu deteriorated SB solders is easily failed.

Enhancing Magnesium-Ion Storage in a Bi-Sn Anode through Dual-Phase Engineering.

Magnesium-ion batteries (MIBs) are a "beyond Li-ion" technology that are hampered by Mg metal reactivity, which motivates the development of anode materials such as tin (Sn) with high theoretical capacity (903 mAh g-1). However, pure Sn is inactive for Mg2+ storage. Herein, Mg alloying with Sn is enabled within dual-phase Bi-Sn anodes, where the optimal composition (Bi66.5Sn33.5) outperformed single-phase Bi and Sn electrodes to deliver high specific capacity (462 mAh g-1 at 100 mA g-1), good cycle life (84% after 200 cycles), and significantly improved rate capability (403 mAh g-1 at 1000 mA g-1). Density functional theory (DFT) calculations revealed that Mg alloys first with Bi and the subsequent formation of the Mg3Bi2//Sn interfaces is energetically more favorable compared to the individual Mg3Bi2 and Sn phases. Mg insertion into Sn is facilitated when Mg3Bi2 is present. Moreover, dealloying Mg from Mg3Bi2:Mg2Sn systems requires the creation of Mg vacancies and subsequent Mg diffusion. Mg vacancy creation is easier for Mg2Sn compared to Mg3Bi2, while the latter has slightly lower activated Mg-diffusion pathways. The computational findings point toward easier magnesiation/demagnesiation for BiSn alloys over pure Bi or pure Sn, corroborating the superior Mg storage performance of Bi-Sn electrodes over the corresponding single-phase electrodes.

Growth kinetics and microstructure evolution of network-like Cu3Sn during thermal aging in Ni/Sn–3.5Ag/Cu transient liquid-phase bonding

The growth kinetics and morphology of network-like Cu3Sn in Ni/SA/Cu system were discussed in this study. After reflowing at 270 °C for 300 s, the solder was completely transformed into full Intermetallic compounds (IMCs) composed of (Cu, Ni)6Sn5 and Cu3Sn phases. During the short-term aging stage, the morphology of Cu3Sn was planar-like, and the growth mechanism was reaction-controlled. With aging treatment time exceeding 120 h, the network-like Cu3Sn emerged, and the growth mechanism transformed to diffusion-controlled. Furthermore, it was confirmed that the grain boundaries of (Cu, Ni)6Sn5 adjacent to the network-like Cu3Sn were high angle.

Comparative Study on Mechanical Properties and Microstructure Evolution of Mg-3Zn-1Mn/Sn Alloy through Ca-La-Ce Addition.

This study systematically investigates the influence of the composite addition of Ce, La, and Ca elements on the microstructure evolution and mechanical properties of Mg-3Zn-1Mn/Sn (wt.%) alloys. It indicates that the strength of Mg-Zn-Mn series alloys is superior to that of Mg-Zn-Sn series alloys, due to the stronger restriction of nanosized Mn particles on the recrystallization process and grain growth compared with Mg2Sn phases. The addition of the Ca-La-Ce elements significantly enhances the strength of the Mg-3Zn-1Sn alloy (YS increased by approximately 92.5%, UTS increased by approximately 29.2%, and EL decreased by nearly 52.2%), while for the Mg-3Zn-1Mn alloy, a balanced effect on both the strength and performance can be achieved. This difference mainly lies in the more pronounced refined effect on the grain size and the formation of a bimodal grain structure with strip-like un-DRXed grains and surrounding fine DRXed grains for the Mg-3Zn-1Sn alloy. In contrast, the addition of the Ca-La-Ce elements has a less obvious hindrance on the recrystallization process in the Mg-Zn-Mn series alloy, while significantly weakening the extrusion texture while refining the grains. Through in-depth characterization and experimental analysis, it is found that Sn and Ca can promote the formation of brittle and fine secondary phases. A nanoscale Sn phase (Mg2Sn phase) is more likely to accumulate at the grain boundaries, and the size of the nanoscale Ca2Mg6Zn3 in Mg-Zn-Mn series alloys is finer and more dispersed than that in Mg-Zn-Sn series alloys, thus strongly hindering recrystallization and refining the recrystallized structure of the alloy.

The Effect of In Concentration and Temperature on Dissolution and Precipitation in Sn-Bi Alloys.

Sn-Bi-based, low-temperature solder alloys are being developed to offer the electronics manufacturing industry a path to lower temperature processes. A critical challenge is the significant microstructural and lattice parameter changes that these alloys undergo at typical service temperatures, largely due to the variable solubility of Bi during the Sn phase. The influence of alloying additions in improving the performance of these alloys is the subject of much research. This study aims to enhance the understanding of how alloying with In influences these properties, which are crucial for improving the alloy's reliability. Using in situ heating synchrotron powder X-ray diffraction (PXRD), we investigated the Sn-57 wt% Bi-xIn (x = 0, 0.2, 0.5, 1, 3 wt%) alloys during heating and cooling. Our findings reveal that In modifies the microstructure, promoting more homogeneous Bi distribution during thermal cycling. This study not only provides new insights into the dissolution and precipitation behaviour of Bi in Sn-Bi-based alloys, but also demonstrates the potential of In to improve the thermal stability of these alloys. These innovations contribute significantly to advancing the performance and reliability of Sn-Bi-based, low-temperature solder alloys.

High Milling Time Influence on the Phase Stability and Electrical Properties of Fe50Mn35Sn15 Heusler Alloy Obtained by Mechanical Alloying.

Fe50Mn35Sn15 Heusler alloy, obtained by mechanical alloying, was subjected to larger milling times in the range of 30-50 h to study the phase stability and morphology. X-ray diffraction studies have shown that the milled samples crystallise in a disordered A2 structure. The A2 structure was found to be stable in the milling range studied, contrary to the computation studies performed on this composition. Using Rietveld refinements, the lattice parameter, mean crystallite size, and lattice strain were computed. The nature of the obtained phases by milling was found to be nanocrystalline with values below 50 nm. A linear increase rate of 0.00713 (h-1) was computed for lattice strain as the milling time increased. As the milling time increases, the lattice parameter of the cubic Heusler was found to have a decreasing behaviour, reaching 2.9517 Å at 50 h of milling. The morphological and elemental distribution-characterised by scanning electron microscopy and energy-dispersive X-ray spectroscopy-evidenced Mn and Sn phase clustering. As the milling time increased, the morphology of the sample was found to change. The Mn and Sn cluster size was quantified by elemental line profile. Electrical resistivity evolution with milling time was analysed, showing a peak for 40 h of milling time.

A good balance between the efficiency of ionizing radiation shielding and mechanical performance of various tin-based alloys: Comparative analysis

The Sn-Bix (x = 30, 40, 50, 60 and 70%) radiation shielding alloys were prepared using a melting process of the alloying material in a ceramic crucible at 200 °C for 120 min. The structural characterization for synthesized samples was carried out using X-ray Diffraction technique (XRD). The hardness and elastic properties of the prepared alloys was measured using micro-indentation creep technology and tensile test machine respectively. XRD pattern indicated that that the crystal size of Sn phase is lowered by increasing Bi concentration in the Sn matrix. The hardness decreases as the dwell time increases. The hardness values and elastic properties (in terms of young modulus) were significantly improved due to the decrease in the crystallite size by increasing Bi content. The stress exponent (n) value increase by increasing Bi content which mean that the mechanical properties improved due to increment of resistance. Furthermore, the produced alloys' nuclear shielding ability was investigated. The μm values were calculated using MCNP simulation code and XCOM software over a broad energy range of 0.015 MeV–15 MeV with good agreement between them. Several characteristics are estimated in order to properly understand the researched alloy's radiation and properties of neutron shielding. The findings showed that a higher Bi concentration causes the crystal size to decrease, improving the radiation shielding and mechanical qualities. The alloy Sn-70% Bi has a maximum increase of vicker hardness, tensile strength, and young's modulus. The findings of the shielding parameters indicate that the alloys under study are efficient gamma shielding materials in contrast to other typical shielding materials and materials that have been examined recently. The highest mechanical efficiency and rather strong gamma-ray shielding capabilities are found in the Sn–70Bi alloy. Owing to its ability to effectively balance mechanical performance and shielding, the Sn–70Bi are approved for use in radiation protection. In addition, when compared to all other manufactured alloys, typical neutron shielding materials, and recently investigated materials, the results further demonstrate that the Sn–70Bi alloy has the best neutron attenuation capability. Furthermore, in terms of mass stopping power (MSP) and projected range (PR), the Sn–70Bi alloy demonstrates the most effective attenuation for alpha particles (He+2) and protons (H+1). These results imply that the Sn–70Bi alloy provide superior mechanical performance and nuclear shielding for a range of applications including industrial, medicinal, and nuclear waste storage in the future.

A level set approach to modelling diffusional phase transformations under finite strains with application to the formation of [formula omitted]

This paper presents a sharp interface formulation for modelling diffusional phase transformations. Grain boundary motion is, in accordance with diffusional phase transformation kinetics, determined by the amount of flux towards the interface and is formulated in a level set framework. This approach enables a computational efficiency that can be expected to be higher than what can be achieved with conventional phase field methods. Compatibility of the interfaces is obtained through an interface reconstruction process, in which the locations of triple junction points are also determined. To ensure local equilibrium and a continuous chemical potential across the interfaces, the chemical composition is prescribed at the phase interfaces. The presented model is used to study the growth of the intermetallic compound (IMC) Cu6Sn5 for a system with Sn electroplated on a Cu substrate. A finite strain formulation is incorporated into the model to investigate the effects of the volume change resulting from the IMC formation. In this formulation, the Cu and Sn phases are allowed to deform plastically. The numerical simulations demonstrate IMC growth rates in agreement with experimental measurements. Moreover, the IMC evolves into a scallop-like morphology, consistent with experimental observations.

Interfacial reaction and strengthening mechanism of thermo-compression bonding foam Ni reinforced SAC105 and SAC105–0.3Ti solder joints

The foam Ni holds great potential as a reinforcement phase, attributed to its distinctive three-dimensional (3D) continuous structure. In this study, high-strength Cu connections were produced by vacuum thermo-compression bonding using Ni foam reinforced SAC105 and SAC105–0.3Ti solders. The microstructure, interfacial morphology and shear strength of the connections with different Ni foam composite solders were systematically examined. The results demonstrate that the incorporation of Ni foam as a reinforcing phase substantially enhances the strength of SAC105 solder. The introduction of foam Ni resulted in the formation of a prismatic (Cu, Ni)6Sn5 phase in the matrix and altered the composition of the IMC layer. As the bonding time increased, (Cu, Ni)6Sn5 further grew in the matrix and formed a double interpenetration structure with the foam Ni. The IMC layer, composed of (Cu, Ni)6Sn5 and Cu3Sn, exhibited a random orientation. The Cu/SAC105–0.3Ti-Foam Ni/Cu joints bonded for 10 min exhibited the highest shear strength of 70.23 MPa. Shearing failure predominantly occurs within the soldering seam. The double interpenetration structure and the random orientation of the interfacial IMC impeded crack propagation, thereby significantly enhancing the strength of the Cu joints.

Rationally constructing metallic Sn-ZnO heterostructure via in-situ Mn doping for high-rate Na-ion batteries

Developing a heterostructure for alloying-based anode for sodium-ion batteries (SIBs) is an efficient solution to accommodate volume change upon sodiation/desodiation and boost sodium storage since it combines the merits of each component. Herein, we report a metallic and microphone-like Sn-Zn0.9Mn0.1O heterostructure via an in-situ Mn doping strategy. Based on theoretical calculations and experimental results, the introduction of Mn into ZnO (a small amount of Mn also diffuses into the Sn lattice) can not only enhance intrinsic electronic conductivity but also reduce the Na+ diffusion barrier inside the Sn phase. When evaluated as anode for SIBs, the obtained heterostructures show a high reversible capacity of 395.1 mAh/g at 0.1 A/g, rate capability of 332 mAh/g at 5 A/g, and capacity retention of almost 100 % after 850 cycles at 5 A/g, indicating its great potential for high-power application of SIBs.

Seis-PnSn: A Global Million-Scale Benchmark Data Set of Pn and Sn Seismic Phases for Deep Learning

Abstract The seismic phases Pn and Sn play a crucial role in investigating the velocity and anisotropic characteristics of the uppermost mantle. However, manually annotating these phases can be time-intensive and prone to subjective interpretation. Consequently, the use of travel-time data for these seismic phases remains limited. Despite the potential of deep learning to address this challenge, the scarcity of extensive training data sets for Pn and Sn presents significant constraints. To address this challenge, our research compiled a global million-scale benchmark data set of Pn and Sn seismic phases, namely Seis–PnSn. The data set is derived from earthquake events with epicenter distances ranging from 1.8° to 18°. The high-quality travel-time data used in this study are all from the International Seismological Centre and span the period 2000 to 2019. The waveform data were sourced from data centers located in different regions of the world under the International Federation of Digital Seismograph Networks. By leveraging the unique attributes of this data set, we trained baseline models and explored the prevailing challenges in deep-learning-based Pn and Sn phase picking as the scope transitions from local to regional epicenter distances. Our results show that the performance of the model is considerably enhanced after training on the proposed data set. Our study is a significant complement to the data foundation for future data-driven Pn and Sn seismic phase-picking studies, which will contribute to enhancing our understanding of the uppermost mantle structure of Earth, for example, the seismic velocity, anisotropy, and attenuation characteristics.

Spontaneous growth of Sn whisker on the hot-dipping Al[sbnd]Sn alloy coating on Fe-Cr-B cast steel

Although the MAX phase solid solutions and spontaneous growth of Sn whiskers had been reported widely, the study on the spontaneous growth of whisker at room temperature on the MAB phase was very rare. In our previous work, the periodic layered structure consisted of alternatively arranged Cr-Al-B MAB phase and FeAl3 was formed during the hot-dip aluminizing of Fe-Cr-B cast steel. Herein, the Cr-(Al, Sn)-B MAB phase solid solution was prepared by HDA of Fe-Cr-B cast steel in a AlSn alloy melt and subsequently thermal diffusion treatment. Sn atoms in the Al melt could partially occupy the positions of Al atoms in the Cr-Al-B MAB phase by A-site replacement approach, which resulted in the formation of the Cr-(Al, Sn)-B MAB phase solid solution. Subsequently, spontaneous growth of β-Sn whisker occurred on the Cr-(Al, Sn)-B MAB phase solid solution at room temperature. The original Sn source was the pure Sn phase among the grains of Cr-(Al, Sn)-B MAB phase solid solution. The mass transport pathway for maintaining the spontaneous growth of Sn whiskers was: pure Sn among the grains of Cr-Al-B MAB phase→ Cr-(Al, Sn)-B MAB phase→ SnO2 → Sn whisker. The spontaneous growth of Sn whisker in the air resulted in the deep grooves covered on the surface of whisker, while, growth in the vacuum resulted in the prism structure at the bottom of whisker. The spontaneous growth of Sn whisker could grow from both the bottom and the tip. The findings will expand the family of MAB phase and help well understand the growth mechanism of Sn whisker.

Tailored eutectic alloy coating for enhanced EMI and X-ray protection by basalt fiber CNT/epoxy composite

In this study, eutectic-Bi–Sn-coated basalt fiber (BF)-reinforced carbon nanotube (CNT)/epoxy hybrid composites were fabricated for dual functionality, i.e., in managing and shielding clinical X-ray radiation and electromagnetic interference (EMI). BF mats were coated with Bi–Sn nanoparticles and subsequently layered with multi-walled CNTs mixed epoxy resin using the vacuum-assisted resin transfer method. High resolution field emission scanning electron microscopy revealed a good dispersion of Bi–Sn nanoparticles over BF and, CNTs within the epoxy matrix. X-ray diffraction analysis confirmed the presence of Bi–Sn, basalt, and CNT phases in the composites. High-resolution Raman spectroscopy revealed characteristic peaks corresponding to the CNTs, epoxy, and Bi–Sn phases. EMI total shielding effectiveness (SET) analysis in the X-band frequency range (8.2–12.4 GHz) demonstrated that the Bi–Sn/BF/CNT/epoxy (S3) exhibits the highest SET value of 30.4 dB, which is attributable to the synergistic effect of the Bi–Sn coating and CNT filler. Analysis of X-ray-radiation leakage revealed that all the composite samples effectively attenuated X-rays with minimal leakage, limited to 6.8 mR. These results indicate the potential of these composites for applications as eco-friendly, non-toxic, and lead-free various industries including healthcare, electronics, aerospace, and defense.

Microstructure and properties of multi-layer laser cladding Cu-10Pb-10Sn anti-friction coating

The preliminary experimental results show that the laser cladding technology can produce a well-formed single-layer lead bronze cladding layer with a thickness of 250 μm. The ideal process parameters of the single-layer laser cladding test were selected to study the multi-layer cladding, and the microstructure and properties of the multi-layer cladding were evaluated. The results show that, the multi-layer cladding is composed of α-Cu, Cu41Sn11, Cu5.6 Sn, Pb, and SnO2 phases. There are fine equiaxed crystals at the top of the cladding layer while columnar crystals growing perpendicular to the fusion line at the bottom. The maximum hardness of cladding layer is 248.2 HV near the bottom fusion line. The wear mechanism of multi-layer cladding layer combines abrasive wear and adhesive wear, with wear weight loss and average friction coefficient of 0.0025 g and 0.1161, respectively. The average shear strength between the substrate and the cladding layer is 129 MPa, the shear fracture mode is ductile fracture. Compared with single-layer cladding, the anti-friction performance of multi-layer cladding is significantly improved.

Counter-intuitive mechanical performance variation in aged low-temperature interconnections in electronic packaging

Different from the conventional aging induced continuous mechanical performance deterioration in solder joints, a counter-intuitive “decrease-increase-decrease” variation in shear strength with a peak value 12 MPa higher than the initial state was captured in aged low-temperature BGA structure Cu/Sn–58Bi/Cu solder joints. The first decrease in shear strength was dominated by the coarsening of Sn and Bi phases. The following increase in shear strength was rooted in the concurrent Bi subgrain strengthening, solid solution strengthening of Bi element in Sn-rich phase and precipitation strengthening induced by the Bi-rich phase particles. The eventual decrease in shear strength was ascribed to severely deteriorated interface between the solder matrix and intermetallic compound layer being the weaker site in the long time aged solder joint. This aging induced strengthening phenomenon is inspiring in mechanical performance optimization and reliability elevation of SnBi-based solder joints for the coming chiplet and heterogeneous integration packaging.

Effects of Sn on Corrosion Resistance of Rare-Earth-Free Mg-2Zn Alloy

Alloys of Magnesium metal have attracted the attention of the automobile industries in the past two decades due to their greater specific strength as well as stiffness. However, increasing the corrosion performance of alloys of magnesium has remained a prime concern in order to attain better performance without using expensive rare-earth elements. In this study, the result of Sn addition (0%, 2%, 4%) to hot rolled binary Mg-2Zn alloy was examined in terms of their corrosion and microstructural properties. To understand microstructural features, optical micrography, and SEM-EDX study were conducted. SEM and EDX analysis confirmed the presence of Sn phase after 2% and 4% addition of Sn. The number of particles increased with the gradual increase in the addition of Sn. However, Sn lowered the melting point of Zn precipitates. Thus, the presence of Zn particles was reduced with the addition of Sn. Electrochemical analyses were conducted in order to study the corrosion performance of the selected alloys by submerging it in NaCl (3.5 wt.%) solution, supported by the SEM micrographs of the corroded surface. It was found that adding tin up to 2% increases corrosion resistance. The addition of 4% Sn, on the other hand, introduced large-size particles of Mg2Sn, leading to local corrosion initiation sites, micro galvanic in nature, and hence, reducing corrosion resistance.