Sb Alloys Research Articles

A comparative analysis of microstructural features, tensile properties and wettability of hypoperitectic and peritectic Sn-Sb solder alloys

Sn-Sb alloys are among the current alternatives for the development of alloys for high-temperature lead-free solders. The Sn-Sb alloys having 5.5wt.% Sb or less are known to have good mechanical properties, and despite the quite low liquidus temperature have been considered adequate in the development of solder joints. The increase in the Sb content up to the limit of solubility in Sn at about 10wt.% is supposed to be detrimental to the mechanical properties due to the extensive formation of an intermetallic compound. Investigations on the interrelation of microstructure of this alloy and the corresponding mechanical properties are fundamental to an appropriate evaluation of its application in solder joints. The present investigation analyses the relationship between microstructural features of the peritectic Sn-10wt.% Sb alloy, solidified under a wide range of cooling rates, and the resulting mechanical properties. A cellular β-Sn matrix, typified by cellular spacings that decrease with the increase in the solidification cooling rate, and Sn3Sb2 particles are shown to characterize the alloy microstructure. The ultimate tensile strength is higher as compared with the corresponding values of the hypoperitectic Sn-5.5wt.% Sb solder alloy, however the elongation is shown to decrease. A comparison with Bi-Ag alloys, considered good high temperature solders alternatives, has shown that the tensile properties of the Sn-10wt.% Sb alloy, including elongation, are significantly higher. Wettability tests have been carried out and the experimental results, according to reports from the literature, are associated with good wettability.

Structural, electronic, magnetic, elastic, and thermal properties of Co-based equiatomic quaternary Heusler alloys

In this research work, we have predicted the physical properties of CoFeZrGe and CoFeZrSb for the first time by utilizing first principle calculations based on density functional theory. The exchange-correlation potentials are treated within the generalized-gradient approximation of Perdew-Burke and Ernzerhof (GGA-PBE). The investigated equilibrium lattice parameters of CoFeCrSi are in agreement with available theoretical data and for CoFeZrZ(Z = Ge,Sb) are 6.0013 and 6.2546 Å respectively. The calculated magnetic moments are 1.01μB/fu, 2μB/fu and 1μB/fu for CoFeZrZ(Z = Ge, Sb and Si) respectively, and agree with the Slater-Pauling rule, Mt=Zt-24. The CoFeZrGe, CoFeZrSb and CoFeZrSi composites showed half-metallic behaviour with 100% spin polarization at equilibrium lattice parameters with band gap of 0.43, 0.70 and 0.59 eV for GGA and an improved band gap of 0.86, 1.01 and 1.08 for GGA + U respectively. Elastic properties are also discussed in this paper and it is found that all the materials are mechanically stable and ductile in nature. The CoFeZrSi alloy is found to be stiffer than CoFeZrZ(Z = Ge and Sb) alloys. The Debye temperatures are predicted by using calculated elastic constants. Moreover, the volume heat capacities (Cv) are investigated by utilizing the quasi-harmonic Debye model.

Enhancing the Creep Resistance of Sn-9.0Zn-0.5Al Lead-Free Solder Alloy by Small Additions of Sb Element

The creep phenomenon is considered as one of the most important deformation mechanisms under working conditions. The present study has examined the microstructure and creep properties of Sn-9.0Zn-0.5Al solder alloy after adding a small amount of Antimony (Sb). Nominal compositions of Sb additions were chosen to be 0, 0.5, 1.0, and 1.5 wt.%. The minimum strain rate was reduced for the Sb containing solder alloy. The stress exponents, n, were found to be around 3.7 for all soldiers at 130°C. The stress exponent increases as the temperature drops from 100°C to 50°C, except for the 1.0% Sb alloy, where n 5.3 - 6.1 at all the temperature range (T = 50°C, 100°C and 130°C). The results reveal that the Sb-containing solder alloys have better creep resistance with greater ductility than the Sb-free alloy due to solid solution strengthening, and intermetallic compound SnSb particle hardening.

Эффект формы при расслаивании твердых растворов в малом объеме на примере сплава Bi--Sb

AbstractThe regularities of the effect of the shape of interphase boundaries in small volume systems on the separation of solutions with an upper critical solution temperature (UCST) are described by the example of Bi–Sb alloy particles with a core–shell configuration. The change in the shape of interphase boundaries is simulated in general by introducing a parameter corresponding to the degree of deviation of the shape of the boundaries from the spherical one. An analysis of the extrema of the Gibbs function revealed regularities in the effect of the shape of the core and shell phases on phase equilibria, the thermodynamic stability of heterogeneous states, and the phase separation diagram. The deviation of the shape of the interphase boundaries from the spherical shape changes the UCST and the mutual solubility of the components. The deformation of the shell of a core–shell particle increases the thermodynamic stability of the heterogeneous state, which contributes to the separation of the solution. The deformation of the core lowers the thermodynamic stability of the heterogeneous state and expands the range of metastable states.

Synergetic enhancement of the electronic/ionic conductivity of a Li-ion battery by fabrication of a carbon-coated nanoporous SnOxSb alloy anode.

The major obstacles which prohibit the practical applications of alloy-type anodes include insufficient ionic/electronic transportations and structural failures. Herein, we report the fabrication of a carbon-coated nanoporous SnSb alloy (NP-SnOxSb@C) and its application as an anode in Li-ion batteries (LIBs). The as-fabricated NP-SnOxSb@C is characterized by SEM and TEM and demonstrates a bi-continuous nanoporous structure. Amorphous carbon is found to be uniformly coated on the alloy surface. When used as an anode for LIB, NP-SnOxSb@C displays a high capacity (850 mA h g-1 after the 50th cycle) and good rate performance of 664 mA h g-1 at 2000 mA g-1. The improved electrochemical performance is mainly due to a high Li+ diffusion coefficient and low charge transfer resistance between the nanoporous structure and conductive carbon layer. The facile material fabrication process and good electrochemical performance enable the practical utilization of this anode for high-performance LIBs.

Pressure dependence of resistivity and magnetic properties in a Mn1.9Cr0.1Sb alloy

We report magnetic-field and hydrostatic pressure dependent electrical resistivity and magnetic properties of a Mn1.9Cr0.1Sb alloy. Upon cooling, the magnetization of Mn1.9Cr0.1Sb exhibits a first-order ferrimagnetic to antiferromagnetic transition at the exchange inversion temperature, TS = 261 K under a 0.1 T magnetic field. Our experimental results show that TS decreases with increasing magnetic field but increase with increasing hydrostatic pressure. The pressure induced transition is accompanied by a large positive baro-resistance of 30.5% for a hydrostatic pressure change of 0.69 GPa. These results show that the lattice parameters as well as the bond distance between Mn-Mn atoms play a crucial role in the magnetic and electronic transport properties of Mn1.9Cr0.1Sb. This sample also exhibits a large inverse magnetocaloric effect with a magnetic entropy change of ΔSm = +6.75 J/kg.K and negative magnetoresistance (44.5%) for a field change of 5 T at TS in ambient pressure which may be useful for magnetic cooling and spintronics applications.

Optical Characterization of AlAsSb Digital Alloy and Random Alloy on GaSb

III-(As, Sb) alloys are building blocks for various advanced optoelectronic devices, but the growth of their ternary or quaternary materials are commonly limited by spontaneous formation of clusters and phase separations during alloying. Recently, digital alloy growth by molecular beam epitaxy has been widely adopted in preference to conventional random alloy growth because of the extra degree of control offered by the ordered alloying. In this article, we provide a comparative study of the optical characteristics of AlAsSb alloys grown lattice-matched to GaSb using both techniques. The sample grown by digital alloy technique showed stronger photoluminescence intensity, narrower peak linewidth, and larger carrier activation energy than the random alloy technique, indicating an improved optical quality with lower density of non-radiative recombination centers. In addition, a relatively long carrier lifetime was observed from the digital alloy sample, consistent with the results obtained from the photoluminescence study.

Influence of Fe-doping on magnetic structure and martensitic transformation in Ni[sbnd]Mn[sbnd]In and Ni[sbnd]Mn[sbnd]Sb alloys

Influence of Fe substitution for Ni on the magnetic properties and martensitic transformation was investigated theoretically in Heusler alloys Ni2Mn1.5Z0.5 (Z = In, Sb). Fe-doping does not change the general magnetic structure of Ni2Mn1.5Z0.5. In both Ni2Mn15In0.5 and Ni1.75Fe0.25Mn1.5In0.5 the austenitic phase is ferromagnetic and martensitic phase is antiferromagnetic, which leads to the large ΔM observed experimentally. But in Ni2Mn1.5Sb0.5 and Ni1.75Fe0.25Mn1.5Sb0.5, the antiferromagnetic state is stable in both austenite and martensite. This difference is mainly related to the different atomic radii of In and Sb, which change the distance between Mn (B) and Mn (D). Parallel or antiparallel coupled Mn moments determine the magnetic properties of these alloys. But the partial moment of Fe is large and its direction reverses after martensitic transformation, which makes it a possible way to adjust the magnetic properties of MSMAs. Calculation also suggests that the substitution of Fe for Ni can lower the martensitic transition driving force and lead to the decrease of phase transition temperature. These results agree well with preceding experimental results and make reasonable explanation for them.

Tailoring Morphology and Size of Microstructure and Tensile Properties of Sn-5.5 wt.%Sb-1 wt.%(Cu,Ag) Solder Alloys

Transient directional solidification experiments, and further optical and scanning electron microscopy analyses and tensile tests, allowed the dependence of tensile properties on the micromorphology and length scale of the dendritic/cellular matrix of ternary Sn-5.5Sb-1Ag and Sn-5.5Sb-1Cu alloys to be determined. Extensive ranges of cooling rates were obtained, which permitted specific values of cooling rate for each sample examined along the length of the casting to be attributed. Very broad microstructural length scales were revealed as well as the presence of either cells or dendrites for the Ag-containing alloy. Hereafter, microstructural spacing values such as the cellular spacing, λ c, and the primary dendritic spacing, λ 1, may be correlated with thermal solidification parameters, that is, the cooling rate and the growth rate. While, for the Cu-containing Sn-Sb alloy, the β-Sn matrix is characterized only by the presence of dendritic arrangements, the Ag-containing Sn-Sb alloy is shown to have high-velocity β-Sn cells associated with high cooling rate regions, i.e., positions closer to the bottom of the alloy casting, with the remaining positions being characterized by a complex growth of β-Sn dendrites. Minor additions of Cu and Ag increase both the yield and ultimate tensile strengths when compared with the corresponding values of the binary Sn-5.5Sb alloy, with a small reduction in ductility. This has been attributed to the homogeneous distribution of the Ag3Sn and Cu6Sn5 intermetallic particles related to smaller λ 1 characterizing the dendritic zones of the ternary Sn-Sb-(Cu,Ag) alloys. In addition, the Ag-modified Sn-Sb alloy exhibited an initial wetting angle consistent with that characterizing the binary Sn-5.5Sb alloy.

Nucleation/growth mechanism of electrocrystallization for As–Sb alloy in hydrochloric acid system

Abstract The initial electrocrystallization of As–Sb alloy on glass carbon (GC) electrode in hydrochloric acid system was studied via cyclic voltammetry (CV) and chronoamperometry measurements. Current transients were presented in dimensionless formation, which showed that the initial nucleation/growth process of As–Sb alloy followed three-dimensional nucleation model with diffusion-controlled growth. Relevant nucleation parameters were calculated by analyzing related current transients. Particular attention was paid to the effect of Sb(III) concentration on the nucleation process during the co-electrodeposition. The quantitative results showed that Sb(III) played a positive effect on enhancing the nucleation rate of As–Sb alloy, leading to the evolution of alloy surface morphology from grain structure to compact layer structure.

Magneto-electronic, thermal, and thermoelectric properties of some Co-based quaternary alloys

In this study, quaternary Heusler alloys CoFeCrZ (Z = Si, As, Sb) were investigated based on the modified Becke–Johnson exchange potential. The electronic structures demonstrated that CoFeCrZ (Z = Si, As, Sb) alloys are completely spin polarized with indirect bandgap and has an integer magnetic moment according to the Slater–Pauling rule. Pugh's and Poisson's ratios showed that these materials are highly ductile with high melting temperatures. The thermal properties comprising the thermal expansion coefficient, heat capacity, and Grüneisen parameter were evaluated at various pressures from 0 to 20 GPa. The Grüneisen parameter values indicated the strong anharmonicity of the lattice vibrations that predominated in these compounds. We also studied the dependency of the thermoelectric transport properties on the temperature, i.e., the thermal conductivity and Seebeck coefficient. These alloys exhibited low lattice thermal conductivity and good Seebeck coefficients at room temperature. The half-metallic structures of these compounds with large band gaps and adequate Seebeck coefficients mean that they are suitable for use in spintronic and thermoelectric device applications.

Lattice distortion tuning of the metamagnetic phase transition in tetragonal Cu2Sb-type Mn1.95V0.05Sb alloy

The lattice distortion of tetragonal Cu2Sb-type Mn1.95V0.05Sb alloy was realized by Li interstitial doping or hydrostatic pressure. The metamagnetic transition temperature was decreased and the thermal hysteresis was widened by either depressurization or increasing interstitial Li content. Its effects on magnetic entropy changes (∆S) and critical field had been studied. Thanks to moderate hydrostatic pressure, the beneficial enhancement of maximum of ∆S was achieved in tetragonal Cu2Sb-type Mn1.95V0.05Sb alloy. Our experiment demonstrates that the interatomic distance between MnII-MnII sites and the electronic density surrounding MnII sites are critical for metamagnetic phase transition.

Nucleation interface of Al-Sb alloys on single crystal Al 2 O 3 substrate

Abstract Lattice structure information of heterogeneous nucleation at nucleation interface was present. The crystal orientation, and interfacial structure characteristic of liquid Al alloys nucleated on the basal surface (0001) Al 2 O 3 single crystal substrate were identified by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) analysis. The preferred crystal orientations of pure Al and Al-1%Sb (mass fraction) alloy adjacent to the nucleation interface were examined as (200) and (220) planes of Al, respectively, and two corresponding orientation relationships were obtained. An improved nucleation efficiency and refined grains were attributed to both the reduced interplanar spacing of preferred orientation and the decrease of lattice misfit from 16.4% to 7.0% in Al-1%Sb/Al 2 O 3 nucleation group.

Thermoelectric power factor of Bi-Sb-Te and Bi-Te-Se alloys and doping strategy: First-principles study

The Bi2Te3-related binary compounds (Bi2Te3, Sb2Te3, Bi2Se3, and Sb2Se3) and ternary alloys [(Bi1-xSbx)2Te3 (BST, 0 ≤ x ≤ 1) and Bi2(Te1-ySey)3 (BTSe, 0 ≤ y ≤ 1)] are known as the high performance room temperature thermoelectric materials. Here, for the first time, we systematically study the thermoelectric transport properties of BST and BTSe alloys by calculating their thermoelectric power factor (PF) as a function of alloy composition ratio x and y, carrier concentration n, and the absolute temperature T. The band valley degeneracy and the band gap are critical to determine the thermoelectric transport properties of ternaries. We find that PFs of p-type BST are comparable to those of binaries, while those of n-type BTSe are not, due to the band structure similarity. And the p-type BST performances are superior to the n-type BTSe due to the longer carrier relaxation time, transport anisotropy, and the band valley degeneracy. We also find that the optimal carrier concentrations which maximize the PFs (nopt) depend on the ternary composition and the transport direction. The bipolar effect is found to be less significant for n-type BTSe due to the large band gap and the large nopt. For p-type poly-crystalline BST, the nopt is between 3 and 4 × 1019 cm−3 and it is achievable by Sb alloying and controlling the concentration of intrinsic defect. However, for n-type polycrystalline BTSe, nopt is ranging between 6 × 1019 cm−3 and 1 × 1020 cm−3 and thereby we need additional extrinsic dopant beyond Se alloying. The defect formation energy calculations reveal that Cl, Br, and I impurities are potential candidates for n-type carrier sources without forming any compensating defect, while F as well as Au is the compensating defect.

Optimization in fabricating skutterudite CoSb3 thermoelectric thin films

CoSb3 based thin films were prepared at room temperature by radio-frequency sputtering and the CoSb3 alloy targets were used with the Co:Sb atomic ratio of 1:3, 1:3.5 and 1:4, respectively. Then the as-deposited thin films were annealed at 300 and 325 °C under argon atmosphere for 1 h. It can be found that the thin films have single skutterudite phase structure when used the Co:Sb (1:3.5) alloy target. Though other films show the primary CoSb3 phase structure, there are some impurity phases can be observed from the X-ray diffraction patterns. For contrast, the thin films prepared by the Co:Sb (1:3.5) alloy target were annealed from 250 to 350 °C with the temperature interval of 25 °C. The results show that the thin film annealed at 325 °C has the best thermoelectric performance.

Correlation of Microstructure and Electrochemical Corrosion Behavior of Squeeze-Cast Ca and Sb Added AZ91 Mg Alloys

The effect of individual and mixed additions of calcium (Ca) and antimony (Sb) on the corrosion behavior of the squeeze-cast AZ91 alloy have been investigated. The corrosion resistance of all modified alloys is better as a result of the refined and reduced volume fraction of the β-Mg17Al12 phase as well as grain refinement. Individual additions are better than mixed additions. The AZ91-1.0Ca (AZX911) alloy comprising individual Ca addition with a continuous network of the Al2Ca phase reveals the lowest corrosion rate. Among the alloys comprising combined additions, the AZ91-2.0Ca-0.3Sb (AZXY9120) alloy exhibits the best corrosion resistance because of the higher and lower volume fractions of the Al2Ca and Ca2Sb phases, respectively.

First-principles investigation of magnetic properties and metamagnetic transition of NiCoMnZ(Z = In, Sn, Sb) Heusler alloys

We employed the density functional theory to investigate the structural, magnetic properties and metamagnetic transition on Mn and Co doped-Ni2MnZ (Z = In, Sn, Sb) Heusler alloys. The calculated formation energy indicates that excess Mn and Co prefer to occupy Z and Ni sites, respectively. The energy difference between austenite and martensite phases exhibits a monotonic increase with Mn doping, and a decrease with Co doping, which are consistent with the trend of experimental martensitic transformation temperature. The evaluated magnetic exchange parameters show a strong dependence on Z element, which can be explained by the super-exchange interaction mediated by Z sp states near the Fermi level. Bond analysis of martensite phase reveals that the strength of MnSb bond is stronger than that of MnIn and MnSn bond and it explains the larger driving magnetic field in NiMnSb than NiMnZ(Z = In, Sn) is need for metamagnetic phase transformation. In addition, we predict NiCoMnZ (Z = Sn, Sb) alloys require a smaller compressive epitaxial strain for metamagnetic transition than NiCoMnIn alloys.

Microstructural and Crystallographic Insights in a Martensite/Austenite Dual Phase Ni–Mn–Sb Alloy

For Ni–Mn–Sb multifunctional alloy, its microstructure and crystallographic information are decisive factors for its multiple magnetic field induced properties, such as magnetic field induced shape memory effect, magneto‐caloric effect, exchange bias effect, and so on. While, studies on such field are rarely conducted. In the present work, a thorough study on microstructural features and crystallographic characteristics has been conducted in a martensite/austenite dual phase coexisting polycrystalline Ni50Mn37Sb13 alloy. Results show that the martensite is self‐organized in plates in the original austenite. The intra‐plate martensite presents a fine lamellar microstructure and each fine lamella corresponds to one martensite variant. Crystallographic orientation analysis indicates that each martensite plate exists four differently oriented martensite variants and they can form three types of twins, type I, type II, and compound twin. Trace analysis results show that the interface between adjacent variants are their twinning plane K1. Further investigation on martensitic transformation orientation relationship reveals that the Pitsch orientation relationship, specified as //and //, is the effective one from austenite to martensite. All the above results offer basic microstructural and crystallographic information on Ni–Mn–Sb alloys and can be useful for further investigation on property optimization of these alloys.

Effect of strain on band alignment of GaAsSb/GaAs quantum wells

GaAsSb/GaAs quantum wells are of great interest for optical communications; however, their band alignment properties are not fully understood, particularly at 35% Sb alloy concentration used for emission at 1.3 μm. We use device simulation methods based on the 8 × 8 k·p theory to explore the effects of GaAsSb/GaAs quantum well composition, width, and strain on the band alignment. Strain-relaxed wells demonstrate type-I alignment and pseudomorphic wells demonstrate type-II alignment, regardless of quantum-well composition or thickness for wells wider than 3 nm. For partially strain-relaxed wells, we determine the band alignment as a function of the interplay of composition, width, and strain. Our calculated results at various strain conditions agree well with published experimental data. This work provides insight on band alignment of GaAsSb/GaAs quantum wells, as well as of embedded quantum dots with strong confinement along the out-of-plane direction.

Interstitial effects of B addition on the metamagnetic transition and magnetocaloric effect in tetragonal Cu2Sb-type Mn1.95Cu0.05Sb alloys

Mn1.95Cu0.05SbBx (x = 0, 0.06 and 0.1) alloys had been prepared and B interstitial effects on metamagnetic transition were studied. The metamagnetic transition temperature was reduced and thermal hysteresis was widened by higher B concentration. The saturation magnetization and the magnetic entropy change were increased by moderate amount of B addition. However, too high B composition led into the sluggish metamagnetic transition. By relating with crystallographic structure, our results further indicated that the electron density of the atoms at MnⅡ position plays critical role on influencing the metamagnetic transition in tetragonal Cu2Sb-type Mn1.95Cu0.05Sb alloys.