Determination of the Fe-rich portion of the Fe-Ni-S phase diagram

The low-temperature, Fe-rich portion of the Fe-Ni-S phase diagram was determined from Fe-Ni-S alloys (2.5,5,10,20, and 30 wt.% Ni, 10 wt % S, balance Fe) heat treated at 100 °C intervals from 900 to 300 °C. The microstructure and microchemistry of the phases in the heat treated Fe-Ni-S alloys were studied using a high-resolution field-emission gun (FEG) scanning electron microscope (SEM), electron probe microanalyzer (EPMA), and analytical electron microscope (AEM). Tieline compositions were obtained by determining the average phase composition and by measuring compositional profiles across interphase interfaces with the EPMA and AEM. At 600 °C and below, at least one phase was <1 Μm in size requiring the use of the AEM for analysis. The measured α + FeS, γ+ FeS, and α + γ + FeS boundaries in the Fe-rich corner of the Fe-Ni-S isotherms are consistent with previous studies. However, two new phases were observed for the first time coexisting with γ and FeS phases: FeNiγ′′ (∼52 wt.% Ni) at 600 and 500 °C and Ni ₃ Fe, ordered Ll ₂,γ′ (∼64 wt.% Ni) at 400 °C. New ternary isotherms are given at 600,500, and 400 °C that include the newly determined γ+γ′′ + FeS and the γ + γ′ + FeS three-phase fields. The effects of S on the phase boundaries of the α + γ phase field and the application of the Fe-Ni-S phase diagram to explain the microstructure and microchemistry of the metallic phases of stony meteorites are also discussed.     

Deformation and phase transformations during the cyclic oxidation of Ni−Al and Ni−Pt−Al

The reversible high-temperature γ′ to β phase transformation may be critical to explaining the unusual high-temperature oxidation behavior of (Ni,Pt)Al alloys and coatings. During high-temperature, high-frequency (1 h) cyclic oxidation in dry, flowing O₂, unprecedented macroscopic deformation was observed in two-phase (γ′+β) cast specimens of Hf-doped Ni−Al at 1,150°C and Hf-doped Ni−Pt−Al at 1,100° and 1,150°C, Outside of this two-phase field or when the cycle frequency was decreased to 100h, no deformation was observed. Using high-temperaturex-ray diffraction in an inert environment, the β-to-γ′ phase ratio was observed to increase above 1,000°C, causing a 2.5% volume change. The addition of platinum appeared to lower the transformation temperature consistent with the deformation observed in castalloys and rumpling of simple and platinum-modified aluminide coatings.     

Reassessment of Ni-Al and Ni-Fe-Al solidus temperatures

Solidus temperatures of the B2 NiAl phase have been determined by high-temperature differential thermal analysis for binary melt compositions Ni_xAl_100−x (45<x<57) and for ternary alloys Fe_yNi_50−yAl₅₀ (0≤y≤50). It was shown that the melting temperature of the stoichiometric Ni₅₀Al₅₀ phase is 1681 °C, which is 43 K higher than some literature data. The solidus line at the Ni-rich side of the Ni-Al phase diagram exhibits a steeper slope than that reported previously. Substituting Fe for Ni, the decrease of solidus temperature along the isoplethal section with 50 at.% Al of the ternary Ni-Fe-Al phase diagram exhibits a steep initial slope of −13 K/at.% Fe for small Fe-fractions, which changes into a nearly linear decrease with an average slope of −8.5 K/at.% Fe.     

Formation,stability and crystal structure of the σ phase in Mo–Re–Si alloys

The formation, stability and crystal structure of the σ phase in Mo–Re–Si alloys were investigated. Guided by thermodynamic calculations, six critically selected alloys were arc melted and annealed at 1600 °C for 150 h. Their as-cast and annealed microstructures, including phase fractions and distributions, the compositions of the constituent phases and the crystal structure of the σ phase were analyzed by thermodynamic modeling coupled with experimental characterization by scanning electron microscopy, electron probe microanalysis, X-ray diffraction and transmission electron microscopy. Two key findings resulted from this work. One is the large homogeneity range of the σ phase region, extending from binary Mo–Re to ternary Mo–Re–Si. The other is the formation of a σ phase in Mo-rich alloys either through the peritectic reaction of liquid + Mo_ss → σ or primary solidification. These findings are important in understanding the effects of Re on the microstructure and providing guidance on the design of Mo–Re–Si alloys.     

Reinvestigation of Ni-solid solution/liquid equilibria in Ni-Al binary and Ni-Al-Zr ternary systems

The present work reports the results of a reinvestigation of the γ liquidus and solidus temperatures of the Ni-Al system and the γ/Ni₅Zr eutectic reaction temperatures in the Ni-Al-Zr system. In the Ni-Al binary system, it is found that the stability of the Ni-rich γ solid solution phase is enhanced by small additions of Al with the melting temperature of the γ phase and that the melting temperature reaches a congruent maximum at a few at.% Al. The temperature of the eutectic reaction L→γ+Ni₅Zr in the Ni-Zr binary edge is confirmed to be 1196 °C by differential thermal analysis (DTA), rather higher than the value reported previously. The reaction temperature increases with Al addition to reach or exceed 1206 °C, forming a “saddle point,” then decreasing to reach 1187 °C or below by flowing into a ternary invariant reaction. These findings can be explained by γ/liquid equilibrium in the Ni-Al binary system.     

Reinvestigation of Ni-solid solution/liquid equilibria in Ni-Al binary and Ni-Al-Zr ternary systems

The present work reports the results of a reinvestigation of the γ liquidus and solidus temperatures of the Ni-Al system and the γ/Ni₅Zr eutectic reaction temperatures in the Ni-Al-Zr system. In the Ni-Al binary system, it is found that the stability of the Ni-rich γ solid solution phase is enhanced by small additions of Al with the melting temperature of the γ phase and that the melting temperature reaches a congruent maximum at a few at.% Al. The temperature of the eutectic reaction L→γ+Ni₅Zr in the Ni-Zr binary edge is confirmed to be 1196 °C by differential thermal analysis (DTA), rather higher than the value reported previously. The reaction temperature increases with Al addition to reach or exceed 1206 °C, forming a “saddle point,” then decreasing to reach 1187 °C or below by flowing into a ternary invariant reaction. These findings can be explained by γ/liquid equilibrium in the Ni-Al binary system.     

The isothermal section of the Ni–Sn–Zn phase diagram at 873 K

The phase equilibria of the Ni–Sn–Zn ternary system were experimentally investigated at 873 K in the framework of the COST Action MP0602. Six ternary phases have been observed and their composition ranges have been determined by EPMA analysis on the annealed alloys. All the binary compounds, excluding Ni₃Sn₄, show a large solubility of the third element. The isothermal section at 873 K, including 17 three phase fields, has been determined.     

High-temperature phase relations in the ternary Ga-Mn-Ni system

Isothermal sections of the ternary Ga-Mn-Ni phase diagram at 800 and 1000 °C have been investigated for alloys with a manganese content below 70 at.% for 800 °C and a content below 65 at.% at 1000 °C. The high-temperature phase relations among the solid phases have been analyzed with diffusion couples and by energy dispersion x-ray spectroscopy (EDX) on quenched two-phase alloys. For these temperatures, the solidus line was determined from quenched alloys from the solid and liquid two-phase region by EDX analysis and the liquidus line by an overall evaluation of the phases found in the quenched alloys. By powder x-ray diffraction (XRD) measurements, the results for the equilibria among the solid phases were confirmed and the lattice parameters for the martensite formed from the β phase have been determined over a wide range of compositions.     

High-temperature phase relations in the ternary Ga-Mn-Ni system

Isothermal sections of the ternary Ga-Mn-Ni phase diagram at 800 and 1000 °C have been investigated for alloys with a manganese content below 70 at.% for 800 °C and a content below 65 at.% at 1000 °C. The high-temperature phase relations among the solid phases have been analyzed with diffusion couples and by energy dispersion x-ray spectroscopy (EDX) on quenched two-phase alloys. For these temperatures, the solidus line was determined from quenched alloys from the solid and liquid two-phase region by EDX analysis and the liquidus line by an overall evaluation of the phases found in the quenched alloys. By powder x-ray diffraction (XRD) measurements, the results for the equilibria among the solid phases were confirmed and the lattice parameters for the martensite formed from the β phase have been determined over a wide range of compositions.     

Thermodynamic Study of Liquid Mg-In-Sn Alloys

Liquid Mg-In-Sn alloys were studied by the emf method using concentration cells with liquid electrolyte. Experiments were performed for 30 alloys along three sections on the Gibbs triangle with constantt = 0.25, 0.50, 0.75 [t = X_Sn/(X_Sn + X_In)] and for magnesium concentration from 0.1 to 0.65 at temperatures from 950 to 1100 K. From the change of the slope of the emf versusT, points on the liquidus surface for sixteen alloys were detected. Calculated partial excess Gibbs energies δG_exMg and partial enthalpies δH_Mg were compared with the results of previous work.     

Phase equilibria in the Ti-rich corner of the Ti-Si-Ga system

Phase relations in the ternary Ti-Si-Ga system have been established experimentally by means of a study of alloy samples in the as-cast condition and annealed at 1350 °C. The alloys were prepared by arc melting. The investigation was carried out using physico chemical methods of analyses (metallography, X-ray powder diffraction, differential thermal analysis, and electron probe microanalysis over a limited composition range with samples containing less than 38 at.% Ga and more than 62 at.% Ti. Liquidus and solidus surface projections, the isothermal section at 1350 °C, and the isopleth at 68 at.% Ti are presented. Three surfaces of primary crystallization of phases have been established: extended ones for Ti₅(Si,Ga)₃ and β (Ti-base solid solution) and a narrow one of Ti₂Ga. The monovariant curves separating these are due to the eutectic reactions L↔β+Ti₅(Si,Ga)₃ and L↔β+Ti₂Ga and to the L+Ti₅(Si,Ga)₃↔Ti₂Ga peritectic reaction. The three-phase region (β+Ti₅(Si,Ga)₃+Ti₂Ga) results from the four-phase eutectic reaction L↔β+Ti₅(Si,Ga)₃+Ti₂Ga. The composition of the ternary eutectic point E and the compositions of the coexisting solid phases have been determined. The solubilities of Si in the gallides, and of Ga in Ti₅Si₃ and of both the elements in Ti are given.     

The Ho-Sn (Holmium-Tin) system

The Ho-Sn phase diagram was established by means of differential thermal, x-ray, and microscopic analyses of 23 as-cast alloys. Seven intermetallics were found to form in the system. Ho₅Sn₃ melts congruently at 1915°C. The intermetallics Ho₅Sn₄, Ho₁₁Sn₁₀, Ho₄Sn₅, HoSn₂, Ho₂Sn₅, HoSn₃ form in peritectic reactions at 1720 ±13,1592 ±11,1144 ±11,1114 ±15,509 ±12, and 420 °C, respectively. Compounds Ho₅Sn₄ and Ho₄Sn₅ were observed for the first time. The Ho-rich eutectic crystallizes at 1252 ±11°C and contains ≅13 at. % tin. The solid solubility of Sn in Ho is about 2.5 at. % and that of Ho in Sn is negligible. The enthalpy of mixing of liquid Ho-Sn alloys was studied by calorimetric method. The limit enthalpy of dissolution of Ho in Sn was calculated to be-78.4 kJ/mol.     

Stable and metastable phase equilibria of the In-Se system

The In-Se phase diagram was redetermined using DTA, x-ray analysis, optical microscopy, TEM, and scanning electron microscopy. In₉Se₁₁ and In₅Se₇ are stable phases at stoichiometric composition and βIn₂Se₃ was observed at 59.6 at % Se. ΒIn₂Se₃ decomposes at 198 °C into γIn₂Se₃ and In₅Se₇. Alloy melts between 33 and 54 at.% Se exhibit a strong tendency for undercooling. Between 50 and 60 at. % Se, the InSe, In₆Se₇, or In₂Se₃ phases solidify directly from the undercooled melt, and the formation of In₅Se₇ and In₉Se₁₁ is suppressed while applying cooling rates between 2 to 10 K/min. The respective undercooled states and metastable phase equilibria are provided.     

The Cr-Ni-V system

The Cr-Ni-V system was investigated at 1100 ‡C using XRD, metallography, and energy dispersive chemical analysis of phases using scanning electron microscopy (SEM). The bcc α phase extends from the Cr-Ni binary to the V-Ni binary and has a maximum solubility of Ni in ternary α phase alloys of ∼12 at. %. A wide fcc γ phase field exists at the Ni corner. A ternary Σ phase (Σ₂) exists; it differs from the binary Ni-V Σ phase (Σ₁). The Σ₁ phase has a tetragonal unit cell with parameters almost double those of a normal Σ phase (Σ₂). Results indicate difficulty in achieving equilibrium states in alloys containing more than 30 at. % V and less than 15 at. % Cr even after 480 h annealing. The phase analysis of alloys annealed for 170 to 480 h suggests Σ₂ first forms through a ternary peritectic reaction to subsequently develop the Σ₁, phase by subsidiary reactions in those ternary alloys in the concentration range where Σ₁ is the stable phase. A tentative reaction scheme, consistent with the phase relations established at 1100 ‡C, is proposed.     

The Cr-Ni-V system

The Cr-Ni-V system was investigated at 1100 ‡C using XRD, metallography, and energy dispersive chemical analysis of phases using scanning electron microscopy (SEM). The bcc α phase extends from the Cr-Ni binary to the V-Ni binary and has a maximum solubility of Ni in ternary α phase alloys of ∼12 at. %. A wide fcc γ phase field exists at the Ni corner. A ternary Σ phase (Σ₂) exists; it differs from the binary Ni-V Σ phase (Σ₁). The Σ₁ phase has a tetragonal unit cell with parameters almost double those of a normal Σ phase (Σ₂). Results indicate difficulty in achieving equilibrium states in alloys containing more than 30 at. % V and less than 15 at. % Cr even after 480 h annealing. The phase analysis of alloys annealed for 170 to 480 h suggests Σ₂ first forms through a ternary peritectic reaction to subsequently develop the Σ₁, phase by subsidiary reactions in those ternary alloys in the concentration range where Σ₁ is the stable phase. A tentative reaction scheme, consistent with the phase relations established at 1100 ‡C, is proposed.     

Intermetallic Compounds Formed in Sn-20In-2.8Ag Solder BGA Packages with Ag/Cu Pads

The interfacial reactions in a Sn-20In-2.8Ag solder ball grid array (BGA) package with immersion Ag surface finish are investigated. After reflow, the Ag thin film dissolves quickly into the solder matrix, and scallop-shaped intermetallic layers, with compositions of (Cu_0.98Ag_0.02)₆(In_0.59Sn_0.41)₅, appear at the interfaces between Sn-20In-2.8Ag solder ball and Cu pad. No evident growth of the (Cu_0.98Ag_0.02)₆(Sn_0.59In_0.41)₅ intermetallic compounds was observed after prolonged aging at 100 °C. However, the growth accelerated at 150 °C, with more intermetallic scallops floating into the solder matrix. The intermetallic thickness versus the square root of reaction time (t ^1/2) shows a linear relation, indicating that the growth of intermetallic compounds is diffusion-controlled. Ball shear tests show that the strength of Sn-20In-2.8Ag solder joints after reflow is 4.4 N, which increases to 5.18 N and 5.14 N after aging at 100 and 150 °C, respectively.     

(Sn1-xZnx)57(In0.78Bi0.22)43低熔点无铅焊料的微观结构表征(英文)

为了寻求一种应用于三维集成电路低温焊接的无铅焊料，基于多组元混合的概念设计并表征(Sn_1-xZn_x)₅₇-(In_0.78Bi_0.22)₄₃ (x=0.10,0.15,0.20，摩尔分数，%)四元合金。采用扫描电子显微镜、X射线衍射仪和差示扫描量热仪研究合金的显微组织、热性能和润湿性。结果表明，合金由金属间化合物BiIn₂、In_0.2Sn_0.8和富Zn固溶体组成。随着Zn添加量的增加，BiIn₂和富Zn相的体积分数增加。合金的熔点低至70℃，源自低熔点金属间化合物In_0.2Sn_0.8和BiIn₂的形成；合金具有良好的润湿性，润湿角约为40°。在合金和Cu板的界面结合处形成一种薄而坚韧的Cu₅Zn₈层，提高焊点可靠性。研究表明，通过多组元混合概念设计合金可以有效提高...     

Phase diagram of the Sn–Zn–Ti system

Equilibrated Sn–Zn–Ti alloys and (Sn + Zn)/α-Ti diffusion couples have been studied by scanning electron microscopy, metallography, and differential scanning calorimetry. For the first time an isothermal section, at 600 °C, of the ternary Sn–Zn–Ti system has been constructed. A previously unknown ternary phase with approximate formula Ti₃Sn₂Zn₆ (probable homogeneity interval in the range Ti₅Sn₄Zn₁₁ to Ti₅Sn₃Zn₁₂) has been found.The solubility ranges of the titanium based solid solutions and the intermetallic phases have been looked for. As far as we could detect and in agreement with theoretical considerations, zinc dissolves more in Ti–Sn phases than tin into Ti–Zn compounds. Titanium additions of 3 and 4 at.% Ti do not influence significantly the Sn–Zn eutectic temperature. The experimentally determined melting enthalpies of the nearly eutectic alloys have values around 100 J g⁻¹.     

New Co-based γ-γ′ high-temperature alloys

New cobalt-based alloys containing ordered L1₂ precipitates have been investigated. With additions of Cr, Mo, Ni, Re, Ta, and V to the ternary Co-Al-W system, two phase γ-γ′ microstructures have been established. Solidus and liquidus temperatures are 100°C–150°C higher than advanced nickel-based single-crystal alloys strengthened with the L1₂ phase. An anomalous rise in flow stress with temperature is observed. Single crystals have been solidified and partitioning during solidification is limited in the ternary system, suggesting a high resistance to convective instabilities. Oxidation at 900°C results in the formation of cobalt oxide. Following oxidation, an inner layer of Al₂O₃ is observed in uncoated Cr-containing alloys and Cr₂O₃ is observed in alloys subjected to chromization.     

Intrinsic and Interdiffusion in Cu-Sn System

Solid-solid diffusion couples assembled with disks of copper, tin and intermetallics (Cu₃Sn and Cu₆Sn₅) were employed to investigate the Kirkendall effect in the copper-tin system at the temperature of 200 °C. In the Cu(99.9%)/Sn diffusion couple, inert alumina particles used as markers were identified in the Cu₆Sn₅ phase, while microvoids were observed at the Cu/Cu₃Sn interface. The Cu(99.9%)/Sn and Cu(99.9%)/Cu₆Sn₅ diffusion couples annealed at 200 °C for 10 days were analyzed for intrinsic diffusion coefficients of Cu and Sn in the Cu₆Sn₅ and Cu₃Sn phases, respectively with due consideration of changes in molar volume. Interdiffusion, integrated and effective interdiffusion coefficients were also calculated for the intermetallic phases. Diffusion couples annealed at 125-400 °C for various times were analyzed for the kinetic parameters such as growth rate constants and activation energies for the formation of Cu₃Sn and Cu₆Sn₅ phases. Uncertainties in the calculated intrinsic diffusivities of Cu and Sn arise mainly from the non-planar morphologies of the interfaces and the non-planar distribution of the markers. Intrinsic diffusion coefficients based on average locations of the marker plane indicate that Cu is the faster diffusing component than Sn in both the Cu₃Sn and Cu₆Sn₅ phases.