Ternary Eutectic Reaction Research Articles

溶融 Zn-11%Al-3%Mg-0.2%Si めっき鋼板のめっき凝固組織

The solidification structure of the coating layer in hot-dip Zn-11%Al-3%Mg-0.2%Si coated steel sheet was studied via metallographic examinations together with the calculation of a phase diagram based on Thermo-Calc. The solidification structure observed, which exhibited a combination of the Zn/Al/MgZn2 ternary eutectic structure, the primary Al phase and the MgZn2 phase, turned out to be different from the predicted one under an equilibrium state in the sense that MgZn2 instead of Mg2Zn11 was observed under the present condition. Excluding the Mg2Zn11 phase from the equilibrium phase diagram, the metastable phase diagram was calculated and excellent agreement obtained between the calculation and the experiment in terms of the solidification structure of the coating layer. Consequently MgZn2 is considered to form easily as the metastable structure known as the Laves phase, because the high cooling rate associated with the present experiment does not provide any potential for peritectic-eutectic reactions, which usually occur in the equilibrium state. Furthermore, MgZn2, which has a C14 type Laves structure and a high rate of nucleation in the liquid phase, is considered to cause the preferential Zn/Al/MgZn2 ternary eutectic reactions.

Phase Equilibria between γ-Fe (A1) and Fe<sub>2</sub>Ti Laves (C14) Phases and Microstructure in Fe-Ti-Ni Ternary System at Elevated Temperatures

The phase equilibria among α-Fe, γ-Fe and Fe2Ti phases in Fe-Ti-Ni ternary system at 1473 K and 1373 K with Ni (γ former element) addition were examined, by paying attention to the γ+Fe2Ti two-phase region. The Fe2Ti single-phase region extends toward the equal-titanium concentration direction up to about 30 at% Ni, and the Laves phase becomes in equilibrium with γ-Fe by 12 at% Ni addition, but the γ+Fe2Ti two-phase region is limited because of the formation of liquid phase by further Ni addition at 1473 K. With decreasing temperature, a ternary eutectic reaction (L→γ-Fe+Fe2Ti+Ni3Ti) occurs, making the two-phase region wider just below the invariant reaction at 1373 K, and the region becomes narrower again by the enlargement of the three-phases region toward Fe-rich side.

Effect of minor niobium addition on microstructure of a nickel-base directionally solidified superalloy

Scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron probe microanalysis (EPMA) and differential scanning calorimetry (DSC) were used to study the effect of minor niobium addition on as-cast microstructure of a nickel-base directionally solidified superalloy. A proper niobium addition resulted in the formation of homogeneous γ′ particles almost with the same size throughout the whole dendrite. The ternary eutectic reaction L → (M 23C 6 + γ + γ′) occurred with increasing niobium content, but no eutectic was found when niobium content was high enough because the NbC preferably precipitated and the eutectic reaction was suppressed.

Phase equilibrium in the cerium-poor Ce–Ni–Cu system

In the framework of preparing metallic substrates for high temperature superconductors of the second generation, the Ce–Ni–Cu system in Ce-poor field has been studied by means of DTA/TG, X-ray diffraction, SEM with EDX attachment and optical microscope. For the solid state equilibrium, the existence of a continuous solid solution Ce(Ni 1− x Cu x ) 5 has been confirmed and it was found that this solid solution extends in poor Ce compositions. No ternary phase could be evidenced in the investigated field. CeCu 6 was found to dissolve up to 5 at.% Ni. The cerium solubility in the (Ni,Cu) solid solution is less than 0.5 at.%. At high temperatures, for the equilibrium implying a liquid phase, a ternary eutectic reaction L ↔ Ce(Ni,Cu) 6 + Ce(Ni,Cu) 5 + (Ni,Cu) occurs at T = 871 °C for Ce 0.10Ni 0.07Cu 0.83, i.e for a Ce composition 1 at.% higher than in the binary systems. Finally, the polythermal section of the system has been estimated and the isoplethic sections with the 16.7 at.% Ce, 14.3 at.% Ce and 9 at.% Ce are proposed.

Fabricating TiC particles reinforced Fe-based composite coatings produced by GTAW multi-layers melting process

The present study aims to analyze microstructure and properties of TiC particles reinforced Fe-based surface composite coatings produced by gas tungsten arc welding (GTAW) multi-layers melting process. The mixture powder of graphite and ferrotitanium (FeTi) was deposited evenly on an AISI 1045 steel substrate, which was then heated by GTAW heat source. The results showed that in situ synthesized TiC particle reinforced composite coatings can be achieved under suitable welding parameters. Cubic TiC carbides and fine needle-shape eutectic TiC carbides are formed by ternary eutectic reaction between FeTi and graphite powders. Together with these TiC carbides, radially grown dendrites of primary TiC particles are also found in the composite coatings. These TiC particles are evenly distributed in the composite coatings. Because of the generation of these carbide particles and their homogeneous distribution in the matrix, the composite coatings give very high hardness and excellent wear resistance. The wear resistance of multi-layers composite coatings is about three to four times higher than that of 1045 steel substrate. Moreover, the wear resistance of the composite coatings and the substrate increased with increasing wear sliding distance.

Contribution to the tin‐rich region of the Sn‐Zn‐Ti system

AbstractThe tin‐rich region of the system Sn‐Zn‐Ti system has been studied by diffusion couples, differential scanning calorimetry and electron microprobe analyses. Ternary eutectic reaction occurs at 193.7°C near to the binary tin‐zinc eutectic point and titanium content less than 0.9 at.% Ti. Three ternary compounds with approximate formulae: Ti8Sn5Zn2 to Ti5Sn3Zn, TiSn4Zn5 and Ti2Sn4Zn3 have been observed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Mathematical modeling of solidification paths in ternary alloys: Limiting cases of solute redistribution

A simple mathematical framework is provided for calculating solidification paths of ternary alloys for equilibrium, paraequilibrium, and nonequilibrium conditions. The results are useful for estimating the possible range of primary solidification paths, the type of monovariant reaction expected to occur, and the relative amount of primary, monovariant eutectic and ternary eutectic constituents that form during solidification. Example calculations show that, for solidification of a ternary eutectic alloy under equilibrium conditions, the monovariant eutectic reaction will only occur when the nominal alloy concentration is above the maximum solid solubility. This result is similar to the binary case. For paraequilibrium conditions, a monovariant eutectic reaction is always expected to occur, but solidification can terminate before the invariant ternary eutectic reaction is reached. Finally, for nonequilibrium conditions, both the monovariant and invariant ternary eutectic reactions are always expected to occur, which is similar to the binary nonequilibrium case. The direction of liquid enrichment on the monovariant eutectic line can also be determined from the results.

Thermodynamic Properties and Melting Behavior of Bi–Sn–Zn Alloys

The partial and integral enthalpies of mixing of liquid Bi–Sn–Zn alloys were determined at 500°C by a drop calorimetric technique using a Calvet-type microcalorimeter. The ternary interaction parameters in the Bi–Sn–Zn system were fitted using the Redlich-Kister-Muggianu model for substitutional solutions, and isoenthalpy curves of the integral molar enthalpy of mixing at 500°C were constructed. Furthermore, a DSC technique was used to determine the liquidus temperatures in three sections (3, 5, and 7 at.% Zn) as well as the invariant reaction temperature of the ternary eutectic L ⇄ (Bi) + (Sn) + (Zn). The ternary eutectic reaction was found at 135°C.

Lead contamination of a transient liquid-phase-processed Sn-Bi lead-free solder paste

The influence of Pb contamination on the solidification behavior of a transient liquid-phase powder-processed Sn-Bi solder paste has been studied using differential scanning calorimetry. The development of low-temperature ternary reactions was found to be very sensitive to both the Pb and Bi content of the solder. Solders with high Bi content favored the formation of the ternary eutectic reaction. Solders with high Pb contents favored the formation of a ternary peritectic reaction. These results agree very well with solidification predictions present in the literature for ternary Sn-Bi-Pb alloys. In particular, the dependence of ternary reactions on composition is due to a change in solidification path. Alloy compositions which mark the transition from one path to the next were identified.

Liquidus Surfaces and Isothermal Section at 973 K of the BaO-ZnO-B<SUB>2</SUB>O<SUB>3</SUB> Pseudo-Ternary System

The liquidus surfaces and the isothermal section at 973 K of the pseudo-ternary BaO-ZnO-B 2 O 3 system were determined using the thermal analysis and X-ray diffraction. The liquidus surface in equilibrium with ZnO spreads over a wide composition range and that in equilibrium with 5ZnO.2B 2 O 3 extends long and narrow toward BaO.B 2 O 3 . The slope of the liquidus surface in equilibrium with ZnO is steep in the region of less than 20 mol%B 2 O 3 but gentle when the B 2 O 1 content exceeds 20mol%. The liquidus surface in equilibrium with 3BaO.B 2 0 3 widely extends and its slope is gentle in the region of less than 30mol%B203 but steep when the B 2 0 3 content exceeds 30 mol%. Pseudo-ternary BaO-ZnO-B 2 O 3 compounds were not found in the composition range investigated. The ternary eutectic reactions are as follows: L -> 3BaO.B 2 0 3 + BaO.B 2 0 3 + ZnO, occurring at 1033 K at the composition 46.5 mol%Ba0-l4.5 mol%ZnO-39.0 mol%B203, L →BaO.B 2 0 3 + ZnO.B 2 0 3 + 5Zn0.2B203, occurring at 1038K at the composition 34mol%BaO-21 mol%ZnO-45mol%B20, L→BaO.2B 2 0 3 +BaO4B 2 0 3 + Zn0.B 2 0 3 , occurring at 1008K at the composition 19mol%BaO-17mol%ZnO-64 mol%B203.

BaO-ZnO-B2O3擬三元系の液相面と973 Kの等温状態図

The liquidus surfaces and the isothermal section at 973 K of the pseudo-ternary BaO-ZnO-B 2 O 3 system were determined using the thermal analysis and X-ray diffraction. The liquidus surface in equilibrium with ZnO spreads over a wide composition range and that in equilibrium with 5ZnO.2B 2 O 3 extends long and narrow toward BaO.B 2 O 3 . The slope of the liquidus surface in equilibrium with ZnO is steep in the region of less than 20 mol%B 2 O 3 but gentle when the B 2 O 1 content exceeds 20mol%. The liquidus surface in equilibrium with 3BaO.B 2 0 3 widely extends and its slope is gentle in the region of less than 30mol%B203 but steep when the B 2 0 3 content exceeds 30 mol%. Pseudo-ternary BaO-ZnO-B 2 O 3 compounds were not found in the composition range investigated. The ternary eutectic reactions are as follows: L -> 3BaO.B 2 0 3 + BaO.B 2 0 3 + ZnO, occurring at 1033 K at the composition 46.5 mol%Ba0-l4.5 mol%ZnO-39.0 mol%B203, L →BaO.B 2 0 3 + ZnO.B 2 0 3 + 5Zn0.2B203, occurring at 1038K at the composition 34mol%BaO-21 mol%ZnO-45mol%B20, L→BaO.2B 2 0 3 +BaO4B 2 0 3 + Zn0.B 2 0 3 , occurring at 1008K at the composition 19mol%BaO-17mol%ZnO-64 mol%B203.

Application of diffusion couple technique for the determination of the Ti-Bi-Sn phase diagram

The system Ti-Bi-Sn has been investigated by solid/liquid diffusion couples at 500, 600, 700 and 800°C. A non-negligible solubility of Sn into solid Bi is found. Diffusion layers of the recently revealed ternary compound Ti3BiSn have been observed, thus its existence has been confirmed. Data about the homogeneity ranges of the binary end-system compounds have been obtained. The assessed growth constants of the diffusion layers are comprised in the interval 10-12 –10-14 m2.s-1. The phases participating in the hypothetical ternary eutectic reaction, probably are: (Bi), (Sn), Liquid and Ti2Sn3. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The phase diagram of the Cd–In–Sn system

Abstract The phase diagram of the Cd–In–Sn ternary system was studied by X-ray powder diffraction analysis and differential scanning calorimetry. 138 alloys were elaborated on nine vertical sections. Three transition peritectic reactions (U-type), two ternary eutectoid reactions (E-type) and one ternary eutectic reaction (E-type) were characterized.

A novel ternary eutectic in the Nb–Al–Ni system

A novel ternary eutectic reaction L → Nb 2Al + Al 3Nb + AlNbNi occurs at the composition of Al–40.4Nb–2.42Ni and the temperature of 1553.6 °C. The third phase is an Al-rich AlNbNi phase with the composition Al–33.3Nb–12.3Ni. Ternary Nb–Al–Ni eutectic exhibits regular microstructure with the predominantly fibrous morphology.

The Al–Ni–Si phase diagram between 0 and 33.3 at.% Ni

The ternary Al–Ni–Si phase diagram between 0 and 33.3 at.% Ni was investigated by a combination of differential thermal analysis (DTA), powder X-ray diffraction (XRD), metallography and electron probe microanalysis (EPMA). Ternary phase equilibria and accurate phase compositions of the respective equilibrium phases were determined within the isothermal section at 550 °C by means of EPMA. Al 3Ni 2 and NiSi 2 were found to form extended ternary solid solutions while Al 3Ni and the ternary phase Al 6Ni 3Si have only small homogeneity ranges within the ternary system. The variation of lattice parameters with the composition was studied for all solid solution phases. DTA was used to investigate ternary phase reactions. A total number of five invariant reactions could be derived from DTA data, i.e. one ternary eutectic reaction, three transition reactions and one ternary peritectic reaction. All experimental data were combined to yield a ternary reaction scheme (Scheil diagram) of the investigated composition range and a liquidus surface projection was constructed based on DTA results. The melting behavior of the extended solid solution phase NiSi 2− x Al x was studied in detail by DTA measurements at low heating rates. The melting reaction was found to change from peritectic decomposition in the binary Ni–Si system to congruent melting at approximately 20 at.% Al.

Determination of the liquidus of the ternary system Cu-Sn-Ti

The liquidus surface of the ternary system Cu-Sn-Ti was established by determining the primary crystallizing phases as well as the phase reactions involving the liquid phase. The τ1CuSn3Ti5 and Ti6Sn5 have a wide field in terms of the primary composition. The primary crystallization of the τ2CuSnTi phase was observed in alloys containing 26 or more at.% Sn and up to 10 at.% Ti. In the tin-rich corner, the liquid phase solidifies in a ternary eutectic reaction.

Non-equilibrium reactions in 6xxx series Al alloys

Laboratory scale techniques have been developed to investigate particular aspects of nucleation and growth during solidification. These techniques have been used to isolate and study under controlled conditions the nucleation and growth aspects of the solidification that may occur in industrial processes such as direct chill (DC) casting, where cooling rates and growth velocities can be relatively high. The resultant intermetallic phase selection has been studied in Al alloys, where a wide range of equilibrium and metastable intermetallics can form. This paper describes the use of the entrained droplet technique together with intermetallic phase identification by transmission electron microscopy (TEM) to study the solidification sequence in a model 6xxx series Al alloy. In the entrained droplet technique, 1–1000 nm liquid droplets are entrained in a solid matrix which acts as a heterogeneous nucleation catalyst, and their solidification is monitored using differential scanning calorimetry (DSC). In the majority of commercial Al alloys, solidification takes place by the formation of primary Al, followed by secondary eutectic and peritectic reactions to form small quantities of intermetallic particles in the interdendritic regions. In the model 6xxx series Al alloy, the solidification sequence observed using the entrained droplet technique after partially melting to 640°C and re-solidifying at a cooling rate of 5 K min −1, showed that the cubic α c-AlFeSi phase was formed via three reactions: (i) the predicted equilibrium peritectic reaction L+Al 13Fe 4→α-Al+α c-AlFeSi; (ii) a non-equilibrium eutectic reaction L→α-Al+α c-AlFeSi; and (iii) a ternary eutectic reaction L→α-Al+α c-AlFeSi+Mg 2Si. Only the peritectic and non-equilibrium eutectic reactions were readily observed during solidification at a cooling rate of 5 K min −1 from the fully molten state. The literature suggests that all the three reactions may operate during commercial casting operations.

Reaction of solder with Ni/Au metallization for electronic packages during reflow soldering

Gold over Ni is one of the most common surface finishes for Cu soldering pads in ball-grid-array (BGA) and other electronic packages. The Au layer is for oxidation protection, and the Ni layer serves as a solderable diffusion barrier. In this study, eutectic Pb-Sn solder-balls were reflowed on the Au/Ni/Cu pads, and the chemical interactions between the solder and the surface finish were studied. Quenched-in microstructures at different stages of the reflow were carefully examined using the scanning electron microscopy. It was found that the solder melted locally along the solder/pad interface at the very early stages of the reflow before the whole solder ball had reached the Pb-Sn eutectic temperature. This was because a ternary eutectic reaction L=(Pb)+(Sn)+AuSn/sub 4/ occurred at 177/spl deg/C, six degrees below the Pb-Sn eutectic temperature. Four distinct stages were identified for the reflow process. The four stages are: (1) partial melting of solder balls and the initial reaction of Au with Sn; (2) complete reaction of An with Sn; (3) separation of (Au/sub x/Ni/sub 1-x/)Sn/sub 4/ from the pad; (4) complete melting of solder balls and the reaction of Ni with Sn. After a typical reflow, with a 225/spl deg/C peak reflow temperature and 115 s reflow time, all the An and Au-bearing intermetallic compounds left the interface and the only intermetallic compound at the interface was Ni/sub 3/Sn/sub 4/ with a thickness of about 2 /spl mu/m.

Effect of Ag Addition on the Microstructural and Mechanical Properties of Sn-Cu Eutectic Solder

The effect of adding Ag up to 1 mass% on the microstructural and mechanical properties of Sn–Cu eutectic solder alloy was examined. Without Ag, primary β–Sn grains are surrounded by the eutectic network band of Cu6Sn5 needle precipitates/β–Sn. With increasing Ag content, the primary β–Sn grain size and the eutectic network size become finer. In the eutectic band fine Ag3Sn particles appear in addition to Cu6Sn5 precipitates. The DSC experiment revealed the presence of four endothermic reactions on heating for Sn–Cu–Ag alloys; the two peaks near 217°C correspond to the Sn–Cu–Ag ternary eutectic melting reaction and those at 223–225°C/224–226°C are for Sn–Cu binary melting. The 0.2% proof stress and tensile strength decrease with the addition of 0.1 mass%Ag and then gradually increase up to 1 mass%Ag. Even with 1% Ag, they are less than the values for a Sn–0.7Cu binary alloy. In contrast, elongation increases with increasing Ag content up to 1%. Thus, the addition of Ag to Sn–0.7Cu alloy can effectively improve its ductility. The strain rate dependence of 0.2% proof stress of Sn–0.7Cu–0.5Ag is similar to that of Sn–Ag eutectic alloy but is different from that of Sn–Cu eutectic alloy. A small amount of added Ag results in a change of the deformation mechanism of Sn–Cu alloy.

Solidification and precipitation behaviour of Al-Si-Mg casting alloys

The effect of Mg content on the solidification and precipitation behaviour of both unmodified and Sr-modified Al-7Si-Mg casting alloys has been investigated at various solidification rates using cooling curve analysis, differential scanning calorimetry (DSC) and optical and electron microscopy. The Mg concentrations covered the range from 0.3 wt% to 0.7 wt%. The results indicate that increasing Mg content or cooling rate lowers the liquidus and binary Al-Si eutectic transformation temperatures. The latent heat of fusion of these alloys is strongly dependent on the level of Si present, but there is no observed dependence on Mg content. The solidification reactions observed under DSC are identified and it is noticed that the ternary eutectic solidification reaction L → Al + Si + Mg2Si is only observed at Mg levels of 0.6% and higher. The minor phases formed on solidification are identified and their response to solution heat treatment is examined. Increasing Mg content usually enhances precipitate hardening. However when Mg levels are increased above 0.5wt%, no apparent increase of yield strength with Mg is observed. This is correlated with dissolved Mg levels and energy released during reprecipitation.