Sn Phase Research Articles

Novel High-Tin Bronze and Nb3Sn Multifilamentary Wires

We developed a method for manufacturing a high Sn concentration bronze material with high ductility. The high-Sn bronze was used to produce multifilamentary wires, and their characteristics were evaluated. To increase the Sn content of the bronze and ensure ductility, the δ-phase (Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">41</sub> Sn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> ), which is a eutectoid when the Sn content is greater than the Cu-Sn solid-solution limit, was replaced with a ternary compound by the addition of Ti. The compound was further refined by hot forging to develop ductility. In this study, 1615-filament wires were produced using the high Sn concentration bronze and a commercial bronze for comparison. Each wire was heat treated with different conditions, and their superconducting properties were evaluated. The area ratio of the Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn phase was higher with the high-Sn bronze alloy irrespective of the heat-treatment temperature. The critical current density was improved for the high-Sn bronze for heat treatment at 625 °C or lower, but when the treatment was performed at 650 °C, the Ti concentration in the Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn phase exceeded 2.0at% and the upper critical magnetic field deteriorated dramatically.

Resolving Mixed Intermediate Phases in Methylammonium-Free Sn–Pb Alloyed Perovskites for High-Performance Solar Cells

HighlightsThe first study dedicated to solving the problem of mixed intermediate phases in methylammonium (MA)-free (FA-Cs) Sn–Pb alloyed perovskite systems, new performance records of 21.61% and 23.82% realized for its single-junction and tandem devices.d-Homoserine lactone hydrochloride (D-HLH), employed as an additive, accelerates the transition from mixed intermediate phases into preformed perovskite nuclei.The presence of D-HLH eliminated the negative effect of mixed intermediate phases and regulated the crystallization kinetics.

Sn-guided self-grown Ge stripes banded by GeSn Nanowires: Formation mechanism and electric-field-induced switching from p- to n-type conduction

The formation of GeSn nanostructures catalyzed by Sn surface droplets during the growth of Ge1-xSnx/Ge/Si(001) heterostructures provide a promising strategy for the growth of high-quality Sn-containing group-IV alloys. The droplet formation is favored by Sn segregation at dislocation cores and diffusion of Sn towards the sample surface. Subsequent Sn droplet motion along 〈110〉 crystallographic directions result in self-assembled Ge stripes along the droplet’s path. A novel phenomenon is observed, for which Sn-rich GeSn nanowires (NWs) were periodically formed on top of Ge(Sn) stripes. While the front edge of the liquid Sn droplet is continuously moving and dissolving the Ge1-xSnx epilayer, the phenomenon of NW periodicity is explained by discrete jumping of the back edge of the droplet resulting in redeposition of material forming the NWs. It is also demonstrated that sn-induced phase separation of metastable Ge1-xSnx epilayers leads to carrier redistribution and an electric-field-induced conductivity type conversion from p- to n-type in the Ge(Sn) stripes. These results advance our understanding of the Sn segregation and phase separation mechanism for Ge1-xSnx epilayers at relatively low temperature (≥230 °C). This study could pave the way for understanding the droplet epitaxy synthesis of Sn-rich GeSn nanostructures generating emergent functionalities of GeSn-based nanodevices.

Microstructure transformation and mechanical properties of Al alloy joints soldered with Ni-Cu foam/Sn-3.0Ag-0.5Cu (SAC305) composite solder

In this study, Ni-Cu/SAC composite solders with different Cu contents were used as an interlayer to solder Al alloy joints at 250 ℃ for different time. The results showed that the formation and evolution of the microstructure were affected by the Cu contents. In the Ni18Cu/SAC joint, the Sn solder was completely consumed to form a solid-phase joint in 5 min. And (Cu,Ni)6Sn5 was the initial phase formed from the reaction between Sn solder and the Ni18Cu skeleton. Due to the higher Ni concentration than (Cu,Ni)6Sn5 phase in the Ni18Cu skeleton, the Ni atoms diffused from Ni18Cu skeleton to the (Cu,Ni)6Sn5 phase and replaced the Cu atoms in it. As a result, the content of Ni atoms in (Cu,Ni)6Sn5 phase increased continuously, and transformed into (Ni,Cu)3Sn4 at 10 min. Phase transition also occurred in the Ni38Cu/SAC joints. However, the initial phase formed from the reaction between Sn solder and the Ni38Cu skeleton was (Ni,Cu)3Sn4. Therefore, the (Ni,Cu)3Sn4 phase was transformed into (Cu,Ni)6Sn5 at 10 min because the Cu atoms diffused from Ni38Cu skeleton to (Ni,Cu)3Sn4. On increasing the soldering time, the shear strength of the joints first increased and then decreased, the Ni18Cu/SAC joints soldered for 10 min exhibited the highest shear strength of 58.3 MPa, the shearing failure mainly happened in the composite solder layers.

Interfacial structures and mechanical properties of Cu/Sn/Cu containing SiC nanowires under transient liquid phase bonding

In order to achieve low-temperature bonding and high-temperature service, Cu/Sn/Cu and Cu/Sn-0.6SiC/Cu structure were fabricated by transient liquid phase (TLP) bonding, and the microstructure evolution of intermetallic compound (IMC) and mechanical performance of TLP bonding solder joints were investigated. The results demonstrated that the scalloped Cu6Sn5 IMC and lamellar Cu3Sn IMC formed at Sn/Cu interface gradually grew up in both solder joints as the bonding time increased. The asymmetrical growth of IMC was formed on both sides at TLP solder joints interface, whereas the interfacial IMC growth rate of Cu/Sn-0.6SiC/Cu was smaller than that of Cu/Sn/Cu solder. After TLP bonding for 120 min, Cu/Sn/Cu structure was composed of total Cu6Sn5 and Cu3Sn IMC and Cu/Sn-0.6SiC/Cu structure still contained remaining Sn phase. SiC nanowires (SiC NWs) dispersed in the solder matrix could impede the growth path between Sn and Cu, so SiC NWs doped to Sn solder could slow down the IMC growth. Moreover, introducing SiC NWs could promote the shear strength of composite solder compared with Sn solder joints during TLP bonding.

Seismic attenuation tomography of the Sn phase beneath the Turkish-Iranian Plateau and the Zagros mountain belt

AbstractThe Turkish-Iranian Plateau and the Zagros highlands are among the most prominent physiographic features in the Middle East and were formed as a result of continental collision between the Arabian and Eurasian plates. To better understand the nature of the lithospheric mantle and the origin of the observed seismic anomalies in this region, we investigated seismic attenuation of the uppermost mantle by detailed measurements of the quality factor of the Sn seismic phase (Sn Q). To that end, we collected a large data set consisting of 30 years (1990–2020) of waveforms recorded by 1266 permanent and temporary seismic stations, applying both the two-station method (TSM) and reverse two-station method (RTM) to measure path-averaged Sn Q. Finally, we performed a tomographic inversion on the path-averaged Sn Q to map the lateral variations of the upper-mantle attenuation across the northern Middle East. Our Sn attenuation maps show moderately low Q (&amp;lt;250) values beneath the Turkish-Iranian Plateau and high Q values (&amp;gt;350) beneath the Zagros and northern edge of the Arabian plate. Furthermore, our Sn Q model is broadly consistent with seismic velocity models in the region suggesting that most of the seismic anomalies are the result of thermal rather than compositional effects.

Enhancement mechanism of Te doping on microstructure, wettability and mechanical properties of Sn–Bi-based solder

Sn–Bi-based solder alloys have sparked tremendous research interest towards the development of low-temperature interconnecting materials in multi-level packaging interconnections electronic devices. Nevertheless, the research speed of solder is elusive to match well with the rapid development of integrated circuit design and manufacturing, which leads to the slow renewal course of electronic products. In the pursue for more effective modification strategies, Te was selected to be doped into Sn58Bi–1Sb (SBS) solder. As expected by the design, Te existed in the solder matrix in the form of solid solution and intermetallic compound simultaneously. To our satisfaction, Te enormously improved both the tensile strength and plasticity of the SBS solder. This largely circumvents the negative correlation between strength and plasticity during the modification process. Additionally, Te element significantly optimized the thermal properties, wettability, and creep resistance of SBS solder. Many tiny Bi particles embedded in Sn phase and strengthened the SBST solder matrix as the second phase. More strikingly, numerous Bi twin crystal structures were observed in the Sn58Bi–1Sb1Te (SBST) solder matrix, which occurred in Sn–Bi-based solder matrixes first time. The Bi phase twin represents preferable deformation ability of Bi phase and the plasticity of the solder matrix. It indicated that the doping of Te comprehensively enhanced the performance of SBS solder and may opened new horizons to the design route of alloying modification for Sn–Bi-based solder.

A distinctive Pb-Sn semi-solid additive manufacturing using wire feeding and extrusion

Based on the semi-solid forming technology, the semi-solid additive manufacturing platform was built in this study, and the forming process was carried out with Pb-Sn wire as raw material. The results showed that when z-axis moving distance of monolayer stacking is 4.2 mm, extruder head temperature reaches 240 °C and heating plate temperature reaches 160 °C, the microstructure is composed of spherical grains of Pb solid solution with average diameter of 13.4 μm and low melting point Sn phase distributed at the grain boundary, the corresponding overlap surface curvature is 0.429 mm−1; The macro morphology also showed the best characteristics with forming effective degree of 0.869 and forming layer height ratio of 1.004. The mechanical properties of semi-solid additive manufacturing sample with optimized processing parameters were tested, the vertical and horizontal tensile strength of the sample are 44.2 and 47.8 MPa respectively, and the elongation in the vertical direction of sample (29.1 %) is significantly higher than that (20.1 %) in the horizontal direction because of double necking phenomena, this deformation mechanical can be explained by the existence of several bonding areas in gauge segment and soft of bonding areas due to enrich of Sn. Finally, Pb-Sn parts with different shapes were formed. This study provides a basis for the further development of semi-solid additive manufacturing for aluminum.

Minimum 1D VP and VP/VS Models and Hypocentral Determinations in the Central Mediterranean Area

Abstract Minimum 1D velocity models and station corrections have been computed for the central Mediterranean area using two main data sets. The first one consists of accurate first arrival-time readings from 103 seismic events with magnitude (ML)≥3.5 recorded by the Italian National Seismic Network (RSN) and the AlpArray Seismic Network (AASN) in the period 2014–2021. Earthquakes were selected on the basis of their spatial distribution, epicentral distance to the nearest seismic station, and maximum distance traveled by Pn and Sn phases. This fine selection of high-quality data combined with the spatial density of the AlpArray seismic stations was decisive in obtaining high resolution for upper mantle velocity, especially in the Alpine belt. To obtain a denser coverage of crustal rays, we extended the first data set with P and S arrivals of local earthquakes from Istituto Nazionale di Geofisica e Vulcanologia (INGV) bulletin data (2016–2018). A total of 75,807 seismic phases (47,183 P phases and 28,264 S phases) have been inverted to calculate best-fit 1D velocity models, at regional and local scales. We then test the performance of the optimized velocity models by relocating the last four years of seismicity recorded by INGV (period 2017–2020). The computed velocity models are very effective for routine earthquake location, seismic monitoring, source parameter modeling, and future 3D seismic tomography.

Effect of Diameter of Nb3Sn-Based Internal-Tin Wires on the Structure of Superconducting Layers

In the present study the structure and morphology of the Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn grains in experimental samples of internal-tin (IT) wires with a distributed diffusion barrier and different wire diameters have been studied by SEM and TEM. The results of these studies demonstrate the strong dependence of the fraction of subelements with residual niobium and cavities in tin sources, as well as the average grain size and composition of Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn phase on the diameter of strands (1.0 mm, 0.7 mm, and 0.5 mm). The results of the analysis of the microstructure help to choose the optimal diameter of strands and show the ways to increase <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J_c</i> to a required level for high-field applications.

Study on the evolution of interfacial (Cu,Ni)6Sn5 and shear property of (111)Cu/Sn/Ni micro joints under isothermal and TG-bonding

Single-crystal Cu can be potentially applied as pad or micro bump in bonding technology for advanced packaging. A novel bonding method with an extra temperature gradient (TG, TG-bonding) was carried out to bonding single-crystal (111)Cu and poly-crystal Ni substrates with Sn as interlayer. The morphology and orientation evolution, elemental distribution and growth kinetics of interfacial (Cu,Ni)6Sn5 intermetallic compound (IMC) in (111)Cu/Sn/Ni micro joints during isothermal and TG-bonding were investigated. Regular roof-type (Cu,Ni)6Sn5 grains along three intersectant directions with an angle of 60° formed at the initial Sn/(111)Cu interface and maintained the roof-type morphology with (112‾0) preferred orientation throughout the isothermal bonding. For TG-bonding, TG-induced atomic thermomigration (TM) and Cu–Ni cross-interaction co-played a critical role in the morphology, grain feature and growth kinetics of the interfacial IMCs. Moreover, rapid growth of (Cu,Ni)6Sn5 phase was achieved by TG-bonding with (111)Cu as hot end to fabricate full IMC joints which had higher shear strength than the cases of isothermal and TG-bonding with (111)Cu as cold end. The proposed method would provide a further insight for developing bonding technology for advanced packaging.

Effects of various second phase ratios and contents on microstructure and mechanical properties of eutectic Sn58Bi alloy

A distinctive low melting point heterostructure alloy (LMH) Sn-Bi-Cu-Zn-Ag-Sb was prepared by introducing different ratios and contents of second phase into the eutectic Sn58Bi alloy (SBE). Rapid solidification results in a dispersion of Cu5Zn8, Ag3Sn, and SbSn precipitated phases in Sn53Bi3Cu3Zn2Ag2Sb (LMH32). Besides, the nano-sized η'-Cu6Sn5 and Ag3Sn phases were also observed in the alloy matrix. During solidification, the Cu5Zn8 and Ag3Sn phases are used as the heterogeneous nucleation matrix of the Sn and Bi phases, which significantly refines the eutectic structure and leads to fine-grained strengthening. And the formation of Sn(Sb) solid solution phase leads to solid solution strengthening. The significant mechanical incompatibility between the matrix and the second phases of the LMHs produces a higher back stress hardening effect. The coupling effect of multiple strengthening mechanisms causes the ultimate tensile strength (UTS) of LMH32 reaches 102 MPa, higher 88.9% than that of SBE, and the elongation reaches 12.8%, but the melting point does not change significantly.

Impact of Ni-coated carbon fiber on the interfacial (Cu,Ni)6Sn5 growth of Sn-3.5Ag composite solder on Cu substrate during reflow and isothermal aging

In this work, a novel composite solder was fabricated by mechanically incorporating Ni-coated carbon fiber (Ni-CF) into the Sn-3.5Ag solder paste in an effort to improve the overall service capability, where the intermetallic compound (IMC) formation and growth is a fundamental issue for consideration. General findings indicated that the addition of Ni-CF did not significantly impact the processing properties of the base alloy, such as melting temperature and wettability, when the reinforcement fraction was less than 2 wt%. Isothermal aging tests were carried out to study the formation and growth of interfacial IMC layers between the composite solder and Cu substrate. The addition of Ni-CF into Sn-3.5Ag solder could effectively promote the formation of interfacial (Cu, Ni)6Sn5 phase during reflow but retard its growth in the solid-state aging. The addition of 1 wt% Ni-CF was believed to be more effective to restrict and reduce the subsequent growth rate of the IMCs during solid-state aging due to the initial formation of a thicker (Cu, Ni)6Sn5 layer after reflow.

Effect of TiO2 nanoparticles on the microstructure, mechanical and thermal properties of rapid quenching SAC355 lead-free solder alloy

PurposeThis study aims to investigate the effect of a small amount of TiO2 NPs addition on the microstructure, thermal, mechanical and electrical properties of environmentally friendly eutectic (SAC355)100-x(TiO2)x (x = 0.1, 0.3, 0.5, 0.7 and 1 wt.%) solder alloys.Design/methodology/approachMechanical, thermal and electrical properties and microstructure conditions are taken into major consideration in any study of materials containing nanoparticles. Dynamic resonance technique, X-ray diffraction and scanning electron microscopy were carried out to study stiffness, identification of the phases and the morphology features of the solder. Structure and microstructure analysis indicated that the presence of rhombohedral β–Sn phase in addition to orthorhombic intermetallic compound (IMC) Ag3Sn and Cu3Sn phase dispersed in Sn matrix. In addition, the results showed that TiO2 NPs addition at a small trace amount into SAC355 system reduces and improves the particle size of both rhombohedral β–Sn and orthorhombic IMC Ag3Sn and Cu3Sn. The interstitial dispersion of TiO2 NPs at grain boundaries resulted in Ag3Sn being more uniform needle-like, which is distributed in the β–Sn matrix. The fine and uniform microstructure leads to improvement of mechanical strength.FindingsSome important conclusions are summarized as follows: microstructure investigations revealed that the addition of TiO2 NPs particles to eutectic SAC355 inhibited in reducing and refines the crystallite size as well as the Ag3Sn IMC, which reinforced the strength of plain solder alloy. The mechanical properties values such as Young’s modulus and Vickers microhardness of SAC355 solder alloy can be significantly improved by adding a trace amount of TiO2 NPs compared with plain solder because of the existence of appropriate volume fraction of Ag3Sn IMC. The results show that the best creep resistance is obtained when the addition of 0.3 wt.% of TiO2 NPs is compared to plain solder. TiO2 NPs addition could increase the melting temperature, compared with plain solder. All results showed that TiO2 NPs addition is an effective method to enhance new solder joints.Practical implicationsNew solder alloys.Originality/valueDevelopment of TiO2 NPs-doped eutectic SAC355 lead-free solder for electronic packaging.

Growth behavior and morphology evolution of interfacial (Cu,Ni)6Sn5 in (001)Cu/Sn/Ni micro solder joints

A novel reflow method with an additional temperature gradient (TG) was performed to bonding single crystal (001)Cu and polycrystal Ni substrates with pure Sn as interlayer. The growth behavior and morphology evolution of interfacial intermetallic compound (IMC) in (001)Cu/Sn/Ni micro solder joints during reflow with and without TG were investigated. (Cu,Ni)6Sn5 phase was found to dominate the IMC growth at all the interfaces, showing significant Cu-Ni cross-interaction. For as-soldered state, prism-type (Cu,Ni)6Sn5 grains formed on the (001)Cu substrate. After isothermal reflow or reflow under TG with Ni as hot end, a single crystal (Cu,Ni)6Sn5 layer formed at the (001)Cu side remaining the prism-type morphology. After reflow under TG with (001)Cu as hot end, the dominant polycrystal (Cu,Ni)6Sn5 IMC formed at the Ni cold end and directionally grew towards the hot end until forming full IMC joint with a much faster growth rate than the other two reflow cases. Cu-Ni cross-interaction and TG played a significant role in IMC growth and morphology/orientation evolution, which was discussed in detail from the respects of lattice misfit and atomic diffusion flux.

Large-scale sodiophilic/buffered alloy architecture enables deeply cyclable Na metal anodes

The application of Na metal anodes is hindered by the formation of dendrites, which evolves from the initial heterogeneous nucleation. The construction of sodiophilic pure metal layers on substrates can partly improve Na deposition behavior, but huge volume change during the repetitive alloy/dealloy process renders their rapid failure, especially under the high depth of discharge. Inspired by the assets of alloy anodes compared with monometallic anodes in Li/Na ion batteries, a Cu6Sn5 alloy layer is constructed on commercial Cu foils with a huge size of 850 mm × 650 mm via a facile electroless Sn plating approach. The sodiophilic Sn phase can alloy with Na and contribute to an ultralow nucleation overpotential as well as dendrite-free morphology. Meanwhile, the inactive Cu phase acts as buffer media to mitigate the internal stress and volume change induced by the alloy reaction, which prevents the alloy layer from peeling. Based on these synergetic effects, the Cu6Sn5 alloy coated Cu current collector gives rise to a highly prolonged Coulombic efficiency (99.84%) for 2000 cycles and 600 h lifetime under an ultrahigh depth of discharge (80%), which is superior to those of single Sn metal-coated Cu current collector. Furthermore, the full cells coupled with FeS2 cathode can stably operate for 1500 cycles with a decent capacity retention of ∼ 95%.

Eutectic intermetallic formation during solidification of a Mg-Sn-Al-Zn-Mn alloy

Multiple primary and eutectic intermetallic compounds (IMCs) often form during the solidification of multicomponent magnesium alloys. Here, we comprehensively explore eutectic intermetallic formation in Mg-4Sn-3Al-1.5Zn-0.6Mn (wt%) as-cast alloy, in comparison with Mg-3Al-1Zn-0.3Mn, to better understand Mg 2 Sn formation during complex multiphase solidification and how it affects the formation of other IMCs. Various IMCs formed at different stages of solidification: τ-AlMn and Al 8 Mn 5 early during solidification and Mg 2 Sn, β-Mg 17 Al 12, and τ-MgAlZn as late forming eutectic phases. Most Mg 2 Sn phase shared a faceted interface with β-Mg 17 Al 12 and τ-MgAlZn grains, forming a fully divorced eutectic particle containing multiple phases. EBSD-based trace analysis in combination with XCT and TEM results revealed that β-Mg 17 Al 12 and τ-MgAlZn phase grew adjacent to the {100} growth facets of Mg 2 Sn. Within multi-phase particles, seven types of reproducible orientation relationships (ORs) were measured between each intermetallic. The ORs between Mg 2 Sn and τ-MgAlZn were found to have the best lattice match among the observed phase pairs. For the defined ORs, Mg 2 Sn can be correlated with the icosahedral coordination in τ-MgAlZn. • Multi-phase eutectic particles investigated in a Mg-4Sn-3Al-1Zn-0.6Mn alloy. • β-Mg 17 Al 12 and τ-MgAlZn phase grew adjacent to the {100} growth facets of Mg 2 Sn. • Reproducible orientation relationships measured between eutectic intermetallics. • For the ORs, Mg 2 Sn correlated best with the icosahedral coordination in τ-MgAlZn.

Mechanochemical preparation of NiCuSn nanoparticles and composites in presence of cetyltrimethylammonium bromide (CTAB) and the catalytic application of the products in homocoupling and hydration of terminal alkynes

We report the synthesis of the NiCuSn nanoparticles and nanocomposites in mechanochemical route using CTAB as milling additive. The study of grinding intensity (frequency) and time interval drew up the importance of the well-chosen operation parameters. The mild milling resulted in formation of NiSn intermetallics, while the intense ones aided the evolution of bronze and copper(I) oxide phases. The utilization of CTAB proved to be the key factor to prevent or slow down the process of mechanical alloying and to fritter the metal grains into the nanodimensions. The dynamic light scattering data demonstrated positively charged particles with average solvodynamic diameters of around 70 nm applying intense or long-term millings. Without CTAB or with relatively short or weak grindings, these values remained between 230 and 550 nm, as in the case of the surface areas getting around 20 m2/g with and 1 m2/g without CTAB. The catalytic transformation of p-methoxyphenylacetylene in dimethyl sulfoxide showed that the copper, copper(I) oxide and bronze particles managed the reaction toward the evolution of 1,3-diyne in Glaser-Hay homocoupling without base addition, while the Sn and SnO2 phases assisted to the Markovnikov-type hydration of alkyne groups. The formation of α-diketone signed that the anti-Markovnikov route was also occurred. The use of CTAB was found to exert a profound effect on the quality of catalytic end-products through the controlled generation of bronze and tin oxide phases and the solid solution of nickel atoms.

Preparation of In/Sn Nanoparticles (In3Sn and InSn4) by Wet Chemical One-Step Reduction and Performance Study

The preparation of binary alloys by surfactant-assisted chemical reduction in aqueous solution at room temperature has become a hot topic. In this article low melting point tin/indium (Sn/In) nanoparticles are synthesized. The formation process of the alloy was studied. Scanning electron microscopy, energy spectrometry, and X-ray diffraction are used to determine the morphology, composition, and crystal structure of the nanoparticles. Study found that fully alloyed indium-tin nanoparticles can be obtained by wet chemical method and the main phases of indium-tin alloy are β-phase (In3Sn) and γ-phase (InSn4). However, the Sn phase appears at a low content of indium (40 wt%). When the content of indium increases to 45 (wt%), the tin phase disappears. In addition, the most important finding is that the composition of the indium-tin alloy can be changed by ratio control, and the content of In3Sn increases with the increase of indium content. The relative content of In3Sn attains a maximum when the content of indium increases to 60 (wt%). In contrast, the content of InSn4 decreases. Finally, differential scanning calorimetry measurements is performed to understand the melting behavior of the nanoparticles and low melting temperatures are achieved for a wide range of indium compositions (from 40% to 60%). The melting temperature is found to be in the range of 125–132 °C and it increased with increasing In3Sn (also the increase of indium content). This gives us a new understanding into the binary alloy nano-system and gives important information for the application of low temperature alloy solders. The choice of composition can be based on the corresponding melting point.

Preparation of a novel multi-layered AlSnCu coating for journal bearings

ABSTRACT This paper described preparation process and tribological performance of a novel overlay material used in journal bearings. A new kind of multi-layered AlSnCu coating with good wear resistance and high load capacity was fabricated by arc assisted magnetron sputtering method. The multi-layered structure was implemented by the intermittent sputtering of Al target during the continuous sputtering of AlSnCu target. As a result, the normal growth of Sn crystals was interrupted by introducing periodic sputtering of Al target, which reduced the size of Sn particles in AlSnCu coating. These small size Sn particles played better anti-friction function under both dry and lubricated conditions. Especially, the self-formed Sn-oil synergic lubricating film played a vital role to enhance its tribological performance in oil environment even under a high applied load of 30 N. Therefore, this novel multi-layered AlSnCu coating with small Sn phase displayed considerable application prospects in journal bearings of diesel engine.