Phase Equilibria in the Cu-Sn-Sb Ternary System

The phase equilibria in the Cu-Sn-Sb ternary system were investigated by means of electron-probe microanalysis and x-ray diffraction. Firstly, ternary solubilities of η-Cu₆Sn₅, δ-Cu₄₁Sn₁₁, Cu₁₁Sb₃, ε-Cu₃Sb and η-Cu₂Sb, were less than 7 at.% Sb or Sn at 400 °C. Besides, an re-stabilized ternary solubility, Cu₆(Sn,Sb)₅, was detected with a homogeneity range of Cu: 52.9-53.3 at.%, Sn: 28.4-30.9 at.%, and Sb: 15.8-18.7 at.%. Its origin was traced back to high-temperature stabilization of the binary η-Cu₆Sn₅ phase. Thirdly, the metastable phase, Cu₁₁Sb₃, was observed at 400 °C in the Cu-Sn-Sb ternary system; On raising the temperature to 500 °C, the ε-Cu₃Sn phase still retained a large solubility for Sb, at?~?16 at.%, while the ε-Cu₃Sb was replaced by β-Cu₃Sb with a dual-cornered large homogeneity range. Similarly, a ternary homogeneity range of Cu: 83.8-84.9 at.%, Sn: 2.6-6.2 at.%, and Sb: 9-12.5 at.%, was found and deduced to be the high temperature stabilization phase of γ-Cu₁₁(Sb,Sn)₂ at 500 °C.     

Synthesis and Structural Characterization of Sb-Doped TiFe<Subscript>2</Subscript>Sn Heusler Compounds

Ternary Heusler compounds form a numerous class of intermetallics, which include two families with general compositions ABC and AB₂C, usually referred to as half- and full-Heusler compounds, respectively. Given their tunable electronic properties, made possible by adjusting the chemical composition, these materials are currently considered for the possible use in sustainable technologies such as solar energy and thermoelectric conversion. According to theoretical predictions, Sb substitution in the TiFe₂Sn full-Heusler compound is thought to yield band structure modifications that should enhance the thermoelectric power factor. In this work, we tested the phase stability and the structural and microstructural properties of such heavily doped compounds. We synthesized polycrystalline TiFe₂Sn_1?xSb_x samples, with x?=?0, 0.1, 0.2 and 1.0 by arc melting, followed by an annealing treatment. The structural characterization, performed by x-ray powder diffraction and microscopy analyses, confirmed the formation of the pseudo-ternary Heusler structure (cF16, Fm-3m, prototype: MnCu₂Al) in all samples, with only few percent amounts of secondary phases and only slight deviations from nominal stoichiometry. With increasing Sb substitution, we found a steady decrease in the lattice parameter, confirming that the replacement takes place at the Sn site. Quite unusually, the as-cast samples exhibited a higher lattice contraction than the annealed ones. The fully substituted x?=?1.0 compound, again adopting the MnCu₂Al structure, does not form as stoichiometric phase and turned out to be strongly Fe deficient. The physical behavior at room temperature indicated that annealing with increasing temperature is beneficial for electrical and thermoelectrical transport. Moreover, we measured a slight improvement in electrical and thermoelectrical properties in the x?=?0.1 sample and a suppression in the x?=?0.2 sample, as compared to the undoped x?=?0 sample.     

Properties of the Ti<Subscript>40</Subscript>Zr<Subscript>10</Subscript>Cu<Subscript>36</Subscript>Pd<Subscript>14</Subscript> BMG Modified by Sn and Nb Additions

The results of investigation of the influence of additions of 2 and 3 at.% of Sn and simultaneously of Sn and 3 at.% Nb on microstructure and properties of the bulk metallic glasses of composition (Ti₄₀Cu_36?x Zr₁₀Pd₁₄Sn _x )_100?y Nb _y are reported. It was found that the additions of Sn increased the temperatures of glass transition (T _g), primary crystallization (T _x ), melting, and liquidus as well as supercooled liquid range (ΔT) and glass forming ability (GFA). The nanohardness and elastic modulus decreased in alloys with 2 and 3 at.% Sn additions, revealing similar values. The 3 at.% Nb addition to the Sn-containing amorphous phase decreased as well all the T _g, T _x , T _L, and T _m temperatures as ΔT and GFA; however, relatively larger values of this parameters in alloys containing larger Sn content were preserved. In difference to the previously published results, in the case of the amorphous alloys containing small Nb and Sn additions, a noticeable amount of the quenched-in crystalline phases was not confirmed, at least of the micrometric sizes. In the case of the alloys containing Sn or both Sn and Nb, two slightly different amorphous phase compositions were detected, suggesting separation in the liquid phase. Phase composition of the alloys determined after amorphous phase crystallization was similar for all compositions. The phases Cu₈Zr_3, CuTiZr, and Pd₃Zr were mainly identified in the proportions dependent on the alloy compositions.     

Improved High-Temperature Microstructural Stability and Creep Property of Novel Co-Base Single-Crystal Alloys Containing Ta and Ti

The influence of Ta and Ti additions on microstructural stability and creep behavior in novel Co-Al-W base single-crystal alloys has been investigated. Compared to the ternary alloy, the γ′ solvus temperature and γ′ volume fraction were raised by individual additions of Ta and Ti, and increased further in the quinary alloy containing both alloying additions. In contrast to ternary and quaternary alloys, an improved microstructural stability with the stable γ–γ′ two-phase microstructure and more than 60% γ′ volume fraction existed in the quinary alloy after prolonged aging treatment at 1050°C for 1000 h. The creep behavior at 900°C revealed lower creep rates and longer rupture lives in the quaternary alloys compared to the ternary alloy, whereas the quinary alloy exhibited even better creep resistance. When the creep temperature was elevated to about 1000°C, the creep resistance of the quinary alloy exceeded the previously reported Co-Al-W-base alloys and first-generation Ni-base single-crystal superalloys. The improved creep resistance at approximately 1000°C was considered to be associated with high γ′ volume fraction, γ′ directional coarsening, and dislocation substructure, which included γ–γ′ interfacial dislocation networks and the sheared γ′ precipitates containing stacking faults and anti-phase boundaries.     

Influence of Nb on microstructure and mechanical properties of Ti-Sn ultrafine eutectic alloy

In this study, A series of the high strength (T₈₂Sn₁₈)_100-xNb_x (x=0, 1, 3, 5, and 9 at%) ultrafine eutectic alloys with large plasticity are developed by suction casting method. The Ti₈₂Sn₁₈ binary eutectic alloy consists of a mixture of a hcp Ti₃Sn and a α-Ti phases having the plate-like lamellar type duplex structure with micro scaled eutectic colony. From the (T₈₂Sn₁₈)₉₇Nb₃, the alloy display structural heterogeneous distribution of ultrafine-scaled phases composed of β-Ti(Nb) solid solution surrounded by alternating plate-like shaped Ti₃Sn and α-Ti phases. With increasing Nb content, the volume fraction of β-Ti is continuously increased, which induced improving mechanical properties both strength and plasticity. Especially, (Ti₈₂Sn₁₈)₉₁Nb₉ alloy has the outstanding combination of the high strength (σ _y ≈1.1 GPa) and large plasticity (ε _p ≈36%) at room temperature.     

Experimental Investigation of the Isothermal Section of the Fe-Mn-Sn System at 723 K

Phase relationships in the Fe-Mn-Sn ternary system at 723 K were investigated using equilibrated approach. More than 40 alloys were prepared by arc-melting method and examined by x-ray powder diffraction, scanning electron microscopy and energy dispersive spectroscopic. The existence of five binary compounds FeSn, FeSn₂, MnSn₂, Mn₃Sn₂, Mn₃Sn and one intermediate solid solution γ(Fe, Mn) have been confirmed in this system. FeSn₂ and MnSn₂ form continuous solid solution (Fe_1?x, Mn _x )Sn₂ (0 ≤ X ≤ 1) and the lattice parameters of (Fe, Mn)Sn₂ reduced linearly with increasing of Fe content. At 723 K, the maximum solid solubilities of Fe in αMn, βMn, Mn₃Sn, Mn₃Sn₂ phases and Mn in FeSn, αFe are about 25, 34.8, 37.3, 46.2 at.% Fe and 26.8, 5.5 at.% Mn respectively. The solid solubilities of γ(Fe, Mn) ranged from 42.1 to 78.1 at.% Fe and the limited solubility of Sn is around 3 at.%. The isothermal section consists of 6 three-phase regions, 13 two-phase regions and 9 single-phase regions. No ternary compound was found at 723 K in this system.     

Isothermal Section of Er-Ag-Sn System at 873 K

The isothermal section of the Er-Ag-Sn system at 873 K was constructed with the use of scanning electron microscopy, energy-dispersive x-ray microanalysis and x-ray powder diffraction. Two ternary compounds were confirmed at this temperature: ErAgSn (LiGaGe structure type, P6₃mc, Z = 2, a = 4.6595(2) Å, c = 7.2872(3) Å) and non-stoichiometric phase ErAg_1?xSn_2+x (Cu₃Au structure type, Pm-3m, Z = 1). For the last one homogeneity range was established (0.08 < x < 0.24) and lattice parameters were determined (a = 4.5007(4), 4.5040(2), 4.5107(1), 4.5412(1) Å for the compositions Er_25.4Ag_23.4Sn_51.2, Er_25.7Ag_23.0Sn_51.3, Er_25.7Ag_21.7Sn_52.6, Er_25.2Ag_18.6Sn_56.2 (at.%) respectively). Melting point of the phase Er_25.7Ag_21.7Sn_52.6 (at.%) was determined to be 1199 K by differential thermal analysis.     

Electrical Transport Properties of Single-Crystalline β-Zn<Subscript>4</Subscript>Sb<Subscript>3</Subscript> Prepared Through the Zn-Sn Mixed-Flux Method

β-Zn₄Sb₃ is a promising p-type thermoelectric material for utilization in moderate temperatures. This study prepares a group of single-crystalline β-Zn₄Sb₃ samples using the Zn-Sn mixed-flux method based on the stoichiometric ratios of Zn_4+x Sb₃Sn _y . The effect of Zn-to-Sn proportion in the flux on the structure and electrical transport properties is investigated. All samples are strip-shaped single crystals of different sizes. The actual Zn content of the present samples is improved (>3.9) compared with that of the samples prepared through the Sn flux method. Larger lattice parameters are also obtained. The carrier concentration of all the samples is in the order of over 10¹⁹ cm^?3. With increasing Sn rate in the flux, this carrier concentration decreases, whereas mobility is significantly enhanced. The electrical conductivity and Seebeck coefficients of all the samples exhibit a behavior that of a degenerate semiconductor transport. Electrical conductivity initially increases and then decreases as the Sn ratio in the flux increases. The electrical conductivity of the x:y = 5:1 sample reaches 6.45 × 10⁴ S m^?1 at 300 K. Benefitting from the electrical conductivity and Seebeck coefficient, the flux proportion of the x:y = 7:1 sample finally achieves the highest power factor value of 1.4 × 10^?3 W m^?1 K^?2 at 598 K.     

Structure,magnetic and magnetocaloric properties of nonstoichiometric TbCo<Subscript>2</Subscript>Ni<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> compounds

The structure and magnetic and magnetocaloric properties of new nonstoichiometric TbCo₂Ni _x compounds (0 ≤ x ≤ 0.4) have been studied. The alloys with х ≤ 0.1 have been shown to be single-phase with the MgCu₂-type structure; in alloys with х > 0.1, an additional phase with a PuNi₃-type structure has been formed. It has been found that the concentration dependences of the Curie temperature and magnetic moment of the 3d-metal sublattice have a maximum at x = 0.025. The magnetocaloric effect magnitude for the TbCo2Nix compounds has been estimated using the results of magnetic and heat-capacity measurements.     

Structure and Stoichiometry of Mg<Subscript>x</Subscript>Zn<Subscript>y</Subscript> in Hot-Dipped Zn–Mg–Al Coating Layer on Interstitial-Free Steel

Correlations of stoichiometry and phase structure of Mg_xZn_y in hot-dipped Zn–Mg–Al coating layer which were modified by additive element have been established on the bases of diffraction and phase transformation principles. X-ray diffraction (XRD) results showed that Mg_xZn_y in the Zn–Mg–Al coating layers consist of Mg₂Zn₁₁ and MgZn₂. The additive elements had a significant effect on the phase fraction of Mg₂Zn₁₁ while the Mg/Al ratio had a negligible effect. Transmission electron microscope (TEM) assisted selected area electron diffraction (SAED) results of small areas Mg_xZn_y were indexed dominantly as MgZn₂ which have different Mg/Zn stoichiometry between 0.10 and 0.18. It is assumed that the Mg_xZn_y have deviated stoichiometry of the phase structure with additive element. The deviated Mg₂Zn₁₁ phase structure was interpreted as base-centered orthorhombic by applying two theoretical validity: a structure factor rule explained why the base-centered orthorhombic Mg₂Zn₁₁ has less reciprocal lattice reflections in the SAED compared to hexagonal MgZn₂, and a phase transformation model elucidated its reasonable lattice point sharing of the corresponding unit cell during hexagonal MgZn₂ (a, b?=?0.5252 nm, c?=?0.8577 nm) transform to intermediate tetragonal and final base-centered orthorhombic Mg₂Zn₁₁ (a?=?0.8575 nm, b?=?0.8874 nm, c?=?0.8771 nm) in the equilibrium state.     

Phase Field Modeling of Joint Formation During Isothermal Solidification in 3DIC Micro Packaging

In this paper, a computational multi-phase field approach is utilized to study the formation of the Cu/Sn/Cu micro-joint in 3-Dimensional Integrated Circuits (3DICs). The method considers the evolution of the system during isothermal solidification at 250 °C for the case of two different interlayer thicknesses (5 and 10 µm). The Cu/Sn/Cu interconnection structure is important for the micro packaging in the 3DIC systems. The thermodynamics and kinetics of growth of η-Cu₆Sn₅ and ?-Cu₃Sn interfacial intermetallics (IMCs) are investigated by coupling the multi-phase field method with CALPHAD approach. The interaction of the phases is addressed by assuming a metastable condition for the Cu/Sn reacting system. The simulations start with the nucleation and rapid growth of the η-Cu₆Sn₅ IMCs at the initial stage, the nucleation and growth of ?-Cu₃Sn IMCs at the intermediate stage ending with the full consumption of Sn layer and the domination of ?-Cu₃Sn IMCs at the later stages. In addition, comparing different diffusion rates through the grain boundary of η phases show that their morphology is the direct consequence of balance of kinetic forces. This work provides a valuable understanding of the dominant mechanisms for mass transport in the Cu/Sn/Cu low volume interconnections. The results show that the phase field modeling is successful in addressing the morphological evolution and growth of IMC layers in the 3DIC joint formation.     

Microstructural evolution of intermetallic compounds in Sn–3.5Ag–X (X = 0, 0.75Ni, 1.0Zn and 1.5In)/Cu solder joints during liquid aging

In this paper, the microstructural evolution of IMCs in Sn–3.5Ag–X (X = 0, 0.75Ni, 1.0Zn, 1.5In)/Cu solder joints and their growth mechanisms during liquid aging were investigated by microstructural observations and phase analysis. The results show that two-phase (Ni₃Sn₄ and Cu₆Sn) IMC layers formed in Sn–3.5Ag–0.75Ni/Cu solder joints during their initial liquid aging stage (in the first 8 min). While after a long period of liquid aging, due to the phase transformation of the IMC layer (from Ni₃Sn₄ and Cu₆Sn phases to a (Cu, Ni)₆Sn₅ phase), the rate of growth of the IMC layer in Sn–3.5Ag–0.75Ni/Cu solder joints decreased. The two Cu₆Sn₅ and Cu₅Zn₈ phases formed in Sn–3.5Ag–1.0Zn/Cu solder joints during the initial liquid aging stage and the rate of growth of the IMC layers is close to that of the IMC layer in Sn–3.5Ag/Cu solder joints. However, the phase transformation of the two phases into a Cu–Zn–Sn phase speeded up the growth of the IMC layer. The addition of In to Sn–3.5Ag solder alloy resulted in Cu₆(Sn_x,In_1?x)₅ phase which speeded up the growth of the IMC layer in Sn–3.5Ag–1.5In/Cu solder joint.     

Optimum Combination of Thermoplastic Formability and Electrical Conductivity in Al–Ni–Y Metallic Glass

Both thermoplastic formability and electrical conductivity of Al–Ni–Y metallic glass with 12 different compositions have been investigated in the present study with an aim to apply as a functional material, i.e. as a binder of Ag powders in Ag paste for silicon solar cell. The thermoplastic formability is basically influenced by thermal stability and fragility of supercooled liquid which can be reflected by the temperature range for the supercooled liquid region (ΔT_x) and the difference in specific heat between the frozen glass state and the supercooled liquid state (ΔC_p). The measured ΔT_x and ΔC_p values show a strong composition dependence. However, the composition showing the highest ΔT_x and ΔC_p does not correspond to the composition with the highest amount of Ni and Y. It is considered that higher ΔT_x and ΔC_p may be related to enhancement of icosahedral SRO near T_g during cooling. On the other hand, electrical resistivity varies with the change of Al contents as well as with the change of the volume fraction of each phase after crystallization. The composition range with the optimum combination of thermoplastic formability and electrical conductivity in Al–Ni–Y system located inside the composition triangle whose vertices compositions are Al₈₇Ni₃Y₁₀, Al₈₅Ni₅Y₁₀, and Al₈₆Ni₅Y₉.     

Correlation between the Hall Resistance and Magnetoresistance in the Mixed State of an Nd<Subscript>2 − <Emphasis Type="Italic">x</Emphasis></Subscript>Ce<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>CuO<Subscript>4 + δ</Subscript> Electronic Superconductor

The Hall resistance and the magnetoresistance in the mixed state of the Nd_{2 ? x}Ce _x CuO_{4 + δ} quasi-two-dimensional system near the antiferromagnetic-superconductor (AF-SC) phase transition have been measured at doping levels x = 0.14 and 0.15, and a correlation has been established. This correlation can be analyzed using the following power relationship: ρ _xy (B) ~ [ρ _xx (B)]^β. It was found that index β varied from 0.94 ± 0.03 in the region of AF and SC coexistence (x = 0.14) to 0.6 ± 0.1 in the SC region with the maximum critical temperature (x = 0.15) at low temperatures and weak magnetic fields. This reduction suggests that the symmetry of carrier pairing changes at the boundary of the transition from the phase of antiferromagnetic ordering and spin density waves to the superconducting phase in the presence of antiferromagnetic spin fluctuations.     

Experimental Investigation of the Isothermal Section at 800 °C of the Nd-Fe-Co Ternary System

The phase equilibrium of the ternary Nd-Fe-Co system at 800 °C was investigated by means of powder x-ray diffraction and scanning electron microscopy–energy dispersive x-ray spectroscopy. Seven binary compounds, i.e., Nd₂Co₁₇, NdCo₅, Nd₅Co₁₉, Nd₂Co₇, NdCo₃, NdCo₂, Nd₂Fe₁₇ were identified to exist at this isothermal section. This isothermal section consists of ten single-phase, ten two-phase and six three-phase regions. All measured compositions and unit-cell refinements were performed at room temperature from quenched samples annealed at 800 °C for one week. The maximum solubility at 800 °C of Fe in NdCo_2?x Fe _x (MgCu₂-type structure, Fd-3 m), NdCo_3?x Fe _x (PuNi₃-type structure, R-3 m space group), Nd₂Co_7?x Fe _x (Ce₂Ni₇-type structure, R-3 m), Nd₅Co_19?x Fe _x (CeCo₁₉-type structure, R-3 m space group), NdCo_5?x Fe _x (CaCu₅-type structure, P6/mmm), Nd₂Co_17?x Fe _x (Th₂Zn₁₇ type structure, R-3 m) and Nd₂Fe_17?x Co _x (Th₂Zn₁₇ type structure, R-3 m) are about 31.6 at.% Fe, 47.9 at.% Fe, 13.3 at.% Fe, 8.6 at.% Fe, 10.37 at.%, 36.35 at.% Fe, and 58.23 at.% Fe respectively. The solid solubility range of Co in Nd₂Fe₁₇ form discontinuous series of 2 ranges is about 0-30.14 at.% Co, and 51.9-100 at.% Co and the solid solubility range of Fe in Nd₂Co₁₇ is about 0-48.1 at.% Fe, and 69.86-100 at.% Fe.     

High-power (Nd,Dy)–(Fe,Co)–B magnets with a low temperature coefficient of induction

High-power (Nd, Dy)–(Fe, Co)–B permanent magnets with a low temperature coefficient of induction (α) were prepared using advantages of strip casting and low-oxygen technologies. The microstructure and temperature dependences of magnetic properties have been studied on sintered (Nd_{1 – x} Dy _x )_13.9(Fe_{1 – y} Co _y )_79.8Cu_0.1Ga_0.1B_6.1 magnets with 0.20 ≤ x ≤ 0.25 and 0 ≤ y ≤ 0.20. The increase in y from 0 to 0.20 is accompanied by an increase in the Curie temperature from 327 to 492°C. This favors a decrease in the value of α from 0.099 to 0.060%/°C, respectively. Magnets with an oxygen content of no more than 2500 ppm which were prepared from the (Nd_0.75Dy_0.25)_13.9(Fe_0.85Co_0.15)_79.8Cu_0.1 Ga_0.1B_6.1 alloy, have the following hysteresis characteristics at 140°C: B _r ≥ 11.3 kG, H _c ≥ 8 kOe, and (BH)_max ≥ 30 MGOe; in this case, α ≤ |–0.07%/°С|.     

Symmetry analysis of the magnetic structures of alloys of the quasi-binary system Fe<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Mn<Subscript>1 − <Emphasis Type="Italic">x</Emphasis></Subscript>Sn<Subscript>2</Subscript>

To estimate the reliability of the literature data on the magnetic structures of quasi-binary alloys Fe _x Mn_{1 ? x} Sn₂ obtained without using methods of symmetry analysis, we calculated the basic functions of the irreducible representations of the space group D _4h ¹⁸ (I4/mcm) with the stars of wave vectors determined from an analysis of previously published models of these structures. A comparison of these models with the results of calculations has been performed. A conclusion is made that the models of magnetic structures examined are in agreement with the results of the symmetry analysis performed in this work.     

Isothermal Section of the Al-Mn-Dy System at 500 °C

Phase relationships in the Al-Mn-Dy ternary system at 500 °C have been investigated by X-ray diffraction, scanning electron microscopy with energy dispersive spectroscopy, and electron probe microanalysis. From the experimental results it was concluded that the isothermal section consists of 16 single-phase regions, 26 two-phase regions and 12 three-phase regions. Two extensive solid solutions, (Al _x Mn_1?x )₁₂Dy and (Al_1?x Mn _x )₂Dy, were observed. The solid solution (Al _x Mn_1?x )₁₂Dy forms by Al replacing Mn in Mn₁₂Dy, while the continuous solid solution (Al_1?x Mn _x )₂Dy forms by Mn and Al mutually substituting in Al₂Dy and Mn₂Dy, respectively. The maximum solid solubility of Al in Mn₁₂Dy is 79.3 at.%.     

The influence of the conditions of synthesis on the composition and mechanical properties of silicon oxycarbonitride nanocomposite films

Dielectric films of hydrogenated silicon oxycarbonitride SiC _x N _y O _z :H were prepared by plasmaenhanced chemical vapor deposition using gas mixtures of 1,1,1,3,3,3-hexamethyldisilazane (HMDS) or 1,1,3,3-tetramethyldisilazane (TMDS) with oxygen and nitrogen in the temperature range of 373–973 K. The effect of the conditions of synthesis on the chemical and phase composition of the films was studied, in the amorphous part of which nanocrystals belonging to the phases of the Si–C–N system α-Si₃N₄, α-Si_3–x C _x N₄, and graphite were distributed. To measure the hardness and Young’s modulus, the nanoindentation method was used. The influence that the synthesis temperature and nitrogen-to-oxygen ratio in the initial gas mixtures HMDS + O₂ + xN₂ and TMDS + O₂ + xN₂ have on the hardness and Young’s modulus of the resulting SiC _x N _y O _z :H films was investigated. The maximum obtained values of these parameters were 20.4 and 201.5 GPa, respectively.