SbSn Phase Research Articles

Correlation of microstructure with thermal and tensile creep properties of novel Sn-5Sb-0.5Cu alloy reinforced with Co particles for soldering applications

The present research examined how cobalt microalloying additions of 0.25, 0.5, 0.75, and 1 weight percent affected the microstructural properties, thermal features, and tensile creep characteristics of eutectic Sn-5 wt% Sb- 0.5 wt% Cu (SSC) lead-free solder alloy. According to the results, cobalt additions of 0.25, 0.5, and 0.75 wt% did not affect SbSn phase but significantly refined β-Sn grains, facilitating the formation of fine fibers (Cu,Co)6Sn5 together with plate-like CoSn3 phases, and preventing the formation of Cu6Sn5 phases. Furthermore, a large amount of cobalt (1 wt%) addition accumulated in the coarsening of the CoSn3 phase. Additions of 0.25 wt% Co, 0.75 wt% Co, and 1 wt% Co did not affect the melting temperatures, but pasty ranges had been slightly lowered, which may enhance the thermal characteristics. Addition of 0.5 wt% Co had unfavorable effects on both melting point and pasty range. This has significant effects on solder reliability and electronic service performance. In terms of creep behavior, the SSC-0.75 wt% Co specimens displayed the highest creep resistance because of the fine dispersion of intermetallic compounds (IMCs) and extended the creep-rupture life to a level that is 3.0 times greater than the SSC baseline. Lower creep resistance was observed in SSC-0.25 wt% Co specimens, which was mostly due to the smaller volume fraction of the precipitate phases and the absence of the CoSn3 phase. Depending on the determined stress exponents and activation energies, it is suggested that the dominant deformation mechanism in SSC-xCo solders is the dislocation climb controlled by short-circuit pipe diffusion across the whole temperature range that was examined.

The electrochemical properties of bismuth-antimony-tin alloy anodes for magnesium ion batteries

Magnesium ion batteries (MIBs) have attracted wide attention due to their high theoretical specific capacity and abundance of Mg resources. However, the kinetics of magnesiation/demagnesiation is slow due to the formation of passive film in the interface between electrolyte and anode if pure Mg is directly employed as anode material. The development of alloy-type anodes is one of the promising strategies to address this issue. In this work, the electrochemical properties of bismuth-antimony-tin (Bi–Sb–Sn) alloy anodes for MIBs have been studied. Bi–Sb–Sn alloys with varied compositions have been synthesized using the mechanical alloying method. The Mg storage mechanism of Bi–Sb–Sn anodes has been clarified and the demagnesiation activity of Mg3Sb2 is improved by Sn substitution for Mg to form SbSn phase. Additionally, the electrochemical behavior of Bi–Sb–Sn anodes shows the formed multi-phase structure and the multi-step phase transition process are beneficial to the transport kinetics of Mg ions and the cycling stability and rate performance of anodes. Specifically, the Bi10Sb10Sn80 anode can deliver high capacity as 417 mAh g−1 at a current density of 500 mA g−1 and 517 mAh g−1 at a current density of 20 mA g−1, respectively.

Impact of precipitated phases on the microstructure and mechanical properties of eutectic Sn58Bi alloy

A new type of low-melting-point heterogeneous alloy (LMH), based on Sn58Bi alloy (SBE), was prepared using Cu, Zn, Ag, and Sb microalloying and rapid solidification. The addition of Cu and Zn elements in equal mass ratios resulted in the Cu5Zn8 phase being dispersed in the Sn55Bi3Cu3Zn (LMH3) alloy. Subsequently, the additional Cu reacted with Sn to form a nano-sized η′-Cu6Sn5 phase at the interface of the Sn-Bi eutectic phase. Sn53Bi3Cu3Zn2Ag2Sb (LMH32) was prepared by adding appropriate amounts of Ag and Sb based on LMH3, leading to the precipitation of Ag3Sn and SbSn phases in the SBE matrix. The different precipitated phases in turn produced different types of fiber textures that existed in the matrix phase of SBE, LMH3, and LMH32. In addition, compared to LMH3, the presence of Ag3Sn and SbSn phases in LMH32 caused the formation of Bi twins identified via electron backscattered diffraction. The twin planes (101̅1) and (11̅02) had corresponding rotation axes and rotation angles of 93.8°[7̅431] and 90.2°[5̅415̅], respectively. Nanoindentation results indicated that LMH32 exhibited higher creep resistance than Sn55Bi3Cu3Zn (LMH3) and SBE. The precipitated phase significantly refines the grain size and eutectic lath structure of the matrix phase (Sn and Bi). During the deformation process, the fine lath structure and the interfacial η′-Cu6Sn5 nanophase can hinder the slippage of the eutectic interface. Moreover, the presence of the precipitated phase forms a large strain gradient in the alloy matrix, which produces a significant back-stress hardening effect and induces substantial dislocation nucleation. The formation of more dislocations made the creep mechanism of LMHs depend on dislocation climbing.

New Insights into Phase Equilibria of the Sb-Sn System

A new experimental investigation of the Sb-Sn phase diagram has been performed. Special attention was focused on the phase equilibria within SbSn-Sb3Sn4 composition range. Phase equilibria have been investigated by DSC measurements combined with a thorough optical and electronic microscopy examination with a special attention to the SbSn-Sb3Sn4 phase transformation. Both DSC and metallographic results have been critically evaluated and debated. The presence of two peritectic reactions L + Sb3Sn4 ⇌ (βSn) at 243 ± 1 °C and L + (Sb) ⇌ (SbSn) at 420 ± 1 °C have been confirmed. The invariant reaction at 321 ± 1 °C has been observed and an additional small effect at about 330-340 °C was systematically recorded. These results have been extensively discussed.

The influence of Ag on the microstructure, thermal properties and mechanical behavior of Sn–25Sb-xAg high temperature lead-free solder

Abstract Adding Ag to Sn–25Sb solder to prepare Sn–25Sb-xAg (x = 0, 2.5, 3.0 and 3.5, x is the mass percentage) solder alloys. Using optical microscope, JSM-5610LV field emission scanning electron microscope, X-ray diffraction (XRD), differential scanning calorimetry (DSC), Vickers hardness tester and tensile testing machine to test the microstructure of the solder alloy, thermal performance and mechanical performance. The microstructure test results of the solder alloys show that Ag3 (Sn, Sb) intermetallic compounds (IMCs) are formed in the Sn–25Sb-xAg (x = 2.5, 3.0 and 3.5) alloys after Ag is added, and they are dispersed in β-Sn phase. Ag3 (Sn, Sb) IMCs are pinned at the grain boundary of β-Sn and SbSn phases. Moreover, it is also found that the addition of Ag makes the β-Sn and SbSn phases in the Sn–25Sb-xAg (x = 2.5, 3.0 and 3.5) solder alloy refined. DSC analysis results show that the melting point of Sn–25Sb-xAg (x = 0, 2.5, 3.0 and 3.5) solder alloy decreases slightly after adding Ag. Among them, the pasty range of Sn–25Sb-2.5Ag solder alloy is the smallest at 12.84 °C, followed by Sn–25Sb-3.5Ag at 14.81 °C. In the mechanical performance test of the solder alloy, it is found that the ultimate tensile strength (UTS) and elongation of the Sn–25Sb-xAg solder alloy increase with the increase of Ag addition. Sn–25Sb-3.5Ag solder alloy has the highest UTS and elongation, which are 69.25 MPa and 8.02% respectively. The increase is mainly through fine-grain strengthening and dispersion strengthening mechanisms.

Thermodynamic reassessment of the Sb-Sn and In-Sb-Sn systems

A modified version of the Sb-Sn phase diagram was proposed that includes both Sb2Sn3 and Sb3Sn4 compounds. Based on this modification, phase equilibria in the In-Sb-Sn system were calculated using a thermodynamic modeling approach. Thermodynamic models for the ternary liquid phase and solid solutions (SbSn) and (Sb2Sn3) were developed. The isopleths xSn = 0.2, 0.5, 0.8, vertical sections xIn/xSb = 3:1, 1:1, 1:3, liquidus surface projection, and isothermal section at 473 K were calculated.

The phase equilibria in the Sb-Sn system – Part II: Experimental results

Based on results from XRD, SEM/EDX and DTA, a new version of the Sb-Sn phase diagram was established that includes the Sb3Sn4 phase with R3¯m space group and a commensurately ordered superstructure that can be derived from stacking seven layers of the conventional rhombohedral SbSn cell. The close structural relationships between these two structures have so far caused Sb3Sn4 to be overlooked in most works. The phase Sb2Sn3, which had been established in some phase diagram versions without clear proof or structural description could be ruled out. Seemingly diverging literature results can now be explained in a consistent way based on a comprehensive literature review in part I and the new data from the present work, part II.

Liquidus Projection and Isothermal Section of the Sb-Se-Sn System

Sb-Se-Sn ternary alloys are promising chalcogenide materials. The liquidus projection and 673.2 K (400 °C) isothermal section of the Sb-Se-Sn ternary system are determined. Numerous Sb-Se-Sn alloys are prepared, and their primary solidification phases are examined. In addition to the three terminal phases, (Sb), (Se) and (Sn), there are Sb2Sn3, SbSn, SnSe, SnSe2, Sb2Se3, Sn2Sb9Se9, and SnSb2Se4 phases. In addition, there are two miscibility gaps along the Sb-Se and Se-Sn and sides. There are ten invariant reactions in the Sb-Se-Sn ternary system, and seven of them are experimentally determined in this study. The lowest reaction temperature of determined invariant reaction is L + SbSn = (Sn) + SnSe at 515.4 K ± 5 K (242.2 °C ± 5 °C). There are nine tie-triangles, which are Liquid + SbSn + SnSe, SbSn + SnSe + (Sb), SnSe + (Sb) + Sn2Sb9Se9, (Sb) + Sb2Se3 + Sn2Sb9Se9, SnSe + Sn2Sb9Se9 + SnSb2Se4, Sb2Se3 + Sn2Sb9Se9 + SnSb2Se4, SnSe + SnSe2 + SnSb2Se4, SnSe2 + SnSb2Se4 + Sb2Se3, and SnSe2 + Sb2Se3 + Liquid in the 673.2 K (400 °C) isothermal section of the Sb-Se-Sn ternary system.

Effect of TiO2 nanoparticle addition and cooling rate on microstructure and mechanical properties of novel Sn1.5Sb0.7Cu solders

The effects of TiO2 nanoparticles and cooling rate on the microstructure and mechanical properties of Sn1.5Sb0.7Cu alloy were investigated. A higher cooling rate and TiO2 nanoparticles refined the primary β-Sn dendrites, Cu6Sn5 and SbSn phase. Especially, the microstructure of the Sn1.5Sb0.7Cu composite solders under the rapid-cooled condition exhibited fine dot-like Cu6Sn5 in the eutectic regions. The improvement in strength was mostly attributed to (1) refinement of the β-Sn grain size; (2) the Orowan strengthening effect; (3) CTE mismatch between reinforcement second phase particles (Cu6Sn5 and TiO2) and the matrix; and (4) the load-bearing effect. However, the total elongation of the composite solders was observed to decrease because of micro-voids both at and along the Cu6Sn5 grain boundary regions. The fracture surfaces of all Sn1.5Sb0.7Cu composite solder were confirmed to exhibit the ductile fracture mode.

Phase equilibria in the ternary Ni–Sb–Sn system: Experiments and calculations

The ternary Ni–Sb–Sn phase diagram was investigated experimentally by a combination of powder X-ray diffraction (XRD), electron probe microanalysis (EPMA), scanning electron microscopy (SEM), and differential thermal analysis (DTA). Ternary phase equilibria were experimentally evaluated for four partial isothermal sections at 1000, 900, and 500°C (for the Ni-rich part) and at 400°C (for the Sb/Sn-rich part) of the system. A continuous solid solution between the two B8-type phases Ni3Sn2 HT(ζ) and NiSb was observed. Although it cannot be proved unequivocally that a similar continuous solid solution exists between the two D03-type phases Ni3Sn HT and β-Ni3Sb (since neither the two binary phases nor any possible ternary solid solution can be retained on quenching) the experimental results suggest indirectly such a continuous solution. The solubility ranges of all other binary phases were determined. The ternary skutterudite-type phase SnyNi4Sb12−xSnx was found to decompose in a ternary peritectic reaction at about 485±5°C. The experimental results, together with additional available literature information, were used to perform a thermodynamic assessment of the ternary system. Five calculated isothermal sections (1000, 900, 500, 400, and 250°C) and three isopleths (xNi/xSn=3/1, 3/2, and 3/4) are presented, together with a Scheil reaction scheme and a liquidus projection for the entire ternary Ni–Sb–Sn system.

Sb-Sn (Antimony-Tin)

The Sb-Sn phase diagram in [Massalski2] was redrawn from [1971Pre]. This phase diagram was updated experimentally and theoretically by [1995Oht], as introduced by [1998Oka]. [2008Man] also got a similar result by thermodynamic modeling. Figure 1 shows the Sb-Sn phase diagram proposed by [2008Che]. The phase diagram was determined by thermodynamic modeling based on experimental data available in the literature supplemented by their own DTA, micrograph, and x-ray diffraction data. This phase diagram differs from the earlier ones most noticeably with regard to the Sb2Sn3 phase. In [Massalski2], this phase exists only in a limited temperature range ( 250320 C). This phase exists at 57 at.% Sn, not at the stoichiometric composition. Its crystal structure is still unknown. [1997Vas] doubted the existence of the b phase having a broad solubility range and proposed the existence of three stoichiometric phases in this system at 34, 48, and probably 50 at.% Sn. There has been no supporting report on this feature since then. References

Interface between Sn–Sb–Cu solder and copper substrate

Influence of antimony and copper in Sn–Sb–Cu solder on the melting and solidification temperatures and on the microstructure of the interface between the solder and copper substrate after wetting the substrate at 623 K for 1800 s were studied. Microstructure of the interface between the solder and copper substrates in Cu–solder–Cu joints prepared at the same temperature for 1800 s was observed and shear strength of the joints was measured. Influence of the atmosphere – air with the flux and deoxidising N 2 + 10H 2 gas – was taken into account. Thermal stability and microstructure were studied by differential scanning calorimetry (DSC), light microscopy, scanning electron microscopy (SEM) with energy-dispersive spectrometry (EDS) and X-ray diffraction (XRD). Melting and solidification temperatures of the solders were determined. An interfacial transition zone was formed by diffusion reaction between solid copper and liquid solder. At the interface Cu 3Sn and Cu 6Sn 5 phases arise. Cu 3Sn is adjacent to the Cu substrate and its thickness decreases with increasing the amount of copper in solder. Scallop Cu 6Sn 5 phase is formed also inside the solder drop. The solid solution Sn(Sb) and SbSn phase compose the interior of the solder drop. Shear strength of the joints measured by push-off method decreases with increasing Sb concentration. Copper in the solder shows even bigger negative effect on the strength.

Experimental investigation and thermodynamic prediction of the Ga–Sb–Sn phase equilibria

Abstract Optimized thermodynamic data, successfully used for phase diagram calculations of constitutive binary systems, were used for prediction of phase equilibria in the ternary Ga–Sb–Sn system. The projection of the liquidus surface, invariant equilibria and three vertical sections with molar ratios Sb:Sn = 1, Ga:Sn = 1 and Ga:Sb = 1 of the Ga–Sb–Sn ternary system were calculated using the CALPHAD method. Alloys, situated along three selected vertical sections, were investigated using differential scanning calorimetry. The experimental phase equilibria data from this work and literature were compared with calculation results.

Phase equilibria of the Sn–Sb–Ag ternary system and interfacial reactions at the Sn–Sb/Ag joints at 400 °C and 150 °C

The isothermal sections of the Sn–Sb–Ag ternary system at 400 °C and 150 °C were determined in this study by experimental examination. At both temperatures, the experimental results are as follows: No ternary compounds were found in the Sn–Sb–Ag system. Two extensive regions of mutual solubility were found. The one located between the two binary isomorphous phases, Ag 3Sn and Ag 3Sb, is labeled ɛ and the other one located between the two binary isomorphous phases, Ag 4Sn and Ag 4Sb, is labeled ζ. The ɛ phase is a very stable phase and is in equilibrium with the ζ, Sb, SbSn, and Sn phases. Each of the Sb and SbSn phases has a limited solubility of Ag. It was found that the equilibrium phases in the isothermal section of the Sn–Sb–Ag ternary system at 400 °C are very similar to those in the section at 150 °C. Besides equilibria determination, the interfacial reactions between Sn–Sb alloys and an Ag substrate were investigated at the same temperatures, producing phase formation results in the Sn–Sb/Ag couples that are very similar to those in Sn/Ag couples.

Formation mechanism of primary phases and eutectic structures within undercooled Pb-Sb-Sn ternary alloys

The solidification characteristics of three types of Pb-Sb-Sn ternary alloys with different primary phases were studied under substantial undercooling conditions. The experimental results show that primary (Pb) and SbSn phases grow in the dendritic mode, whereas primary (Sb) phase exhibits faceted growth in the form of polygonal blocks and long strips. (Pb) solid solution phase displays strong affinity with SbSn intermetallic compound so that they produce various morphologies of pseudobinary eutectics, but it can only grow in the divorced eutectic mode together with (Sb) phase. Although (Sb) solid solution phase and SbSn intermetallic compound may grow cooperatively within ternary eutectic microstructures, they seldom form pseudobinary eutectics independently. The (Pb)+(Sb)+SbSn ternary eutectic structure usually shows lamellar morphology, but appears as anomalous eutectic when its volume fraction becomes small. EDS analyses reveal that all of the three primary (Pb), (Sb) and SbSn phases exhibit conspicuous solute trapping effect during rapid solidification, which results in the remarkable extension of solute solubility.

The 260 °C phase equilibria of the Sn–Sb–Ag ternary system and interfacial reactions at the Sn–Sb/Ag joints

The isothermal section of the Sn–Sb–Ag ternary system at 260 °C has been determined in this study by experimental examination. Experimental results show no existence of ternary compounds in the Sn–Sb–Ag system. Two extensive regions of mutual solubility have been determined. The one located between the two binary isomorphous phases, Ag 3Sn and Ag 3Sb, is labeled as ɛ and the other one located between the two binary isomorphous phases, Ag 4Sn and Ag 4Sb, is labeled as ξ. The ɛ phase is a very stable phase and is in equilibrium with ξ, Sb, SbSn, Sb 2Sn 3, and liquid Sn phases. Each of the Sb and SbSn phases has a limited solubility of Ag. Only one stoichiometric compound, Sb 2Sn 3, exists. Besides phase equilibria determination, the interfacial reactions between the Sn–Sb alloys and the Ag substrate were investigated at 260 °C. It was found that the phase formations in the Sn–Sb/Ag couples are very similar to those in the Sn/Ag couples.

The 260 °C phase equilibria of the Sn–Sb–Cu ternary system and interfacial reactions at the Sn–Sb/Cu joints

The isothermal section of the Sn–Sb–Cu ternary system at 260 °C has been determined in this study by experimental examination. Experimental results show no existence of ternary compounds in the Sn–Sb–Cu system. An extensive region of mutual solubility existing between the two binary isomorphous phases, Cu 3Sn and Cu 4Sb, was determined and labeled as δ. Intermetallic compounds (IMCs) Cu 2Sb, SbSn, and Cu 6Sn 5 are in equilibrium with the δ solid solution. Up to about 6.5 at.%Sb can dissolve in the Cu 6Sn 5 phase, and the solubility of Sn in the Cu 2Sb is approximately 6.2 at.%. Each of the Sb and SbSn phases has a limited solubility of Cu. Only one stoichiometric compound, Sb 2Sn 3, exists. Besides phase equilibria determination, the interfacial reactions between the Sn–Sb alloys and Cu substrates were investigated at 260 °C. Sb was observed to be present in the Cu 6Sn 5 and δ phases, and Sb did not form Sn–Sb IMCs in the interfacial reactions. Moreover, the addition of up to 7 wt% of Sb into Sn does not significantly affect the total thickness of IMC layers. It was found that the phase formations in the Sn–Sb/Cu couples are very similar to those in the Sn/Cu couples.

Experimental investigation and thermodynamic description of the In–Sb–Sn ternary system

Phase equilibria in the In–Sb–Sn ternary system have been studied experimentally and calculated by the CALPHAD method. Solubility of indium in the SbSn phase was experimentally established. Our own SEM–EDX results were used together with the literature data for thermodynamic modeling of the Gibbs energy of the SbSn intermediate phase. Optimized phase diagrams of the isothermal sections at 100 °C and 300 °C were compared with the experimental results from this work and literature. Three calculated vertical sections were compared with the DTA results from this work and with available thermal analysis data reported in the literature. Some calculated thermodynamic functions are compared with experimental values reported in the literature. Reasonable agreement between calculations and experimental data was observed in all cases.

Phase equilibria and thermodynamics of the Bi–Sb–Sn ternary system

Phase equilibria in the Bi–Sb–Sn ternary system have been studied experimentally as well as by using the calculation of phase diagram (CALPHAD) method. New experimental SEM-EDX and DTA results were used together with the literature data in this thermodynamic assessment. Solubility of bismuth in SbSn phase and ternary corrections for Liquid and Rhombo_A7 phase were established. Calculated values of thermodynamic functions were collated with recently published experimental thermodynamic results for liquid phase at 900 K. Calculated isothermal sections at 200 °C and 300 °C were compared with our own experimental results based on the SEM-EDX analysis of composition of phases. Three calculated vertical sections were successfully compared with the DTA results from this work and from literature data. Reasonable agreement between calculation and experimental data was observed in all cases.

Effect of Sb Addition on Microstructure and Shear Strength of Sn-Ag Solder Joints

The effect of Sb addition on microstructure, intermetallic compound (IMC) and mechanical properties of Sn-Ag solder joints is investigated. The compositions of selected solders are Sn2.58Ag, Sn2.82Ag1.75Sb, Sn2.87Ag4.75Sb and Sn2.7Ag8.78Sb. Experimental results show that most of the added Sb are solved in -Sn matrix, and the rest react with the Ag3Sn to form Ag3(Sb,Sn) phase, which contributes to suppress the coarsening of Ag3Sn phase. SbSn phase can be observed in β-Sn matrix as the Sb addition exceeds 4.75% and remains stable during the thermal storage test. The solder microhardness increases with increasing Sb. And the growth rate of interfacial IMC layer decreases as Sb addition increases. EPMA analysis indicates there are some Sb diffusing into the interfacial IMC layer. Shear strength of solder joints are raised by adding Sb. The shear strength by as-soldered condition are 27.8MPa (0%Sb), 29MPa (1.75%Sb), 30.4MPa (4.75%Sb) and 43.4MPa (8.78%Sb) respectively