Ternary Alloy Phase Research Articles

The isothermal section of the phase diagram of Gd-Mn-Ga (≤50 at.%Ga) ternary system at 873K

The phase diagram of the Gd-Mn-Ga ternary system is a very important tool for the exploration and development of rare earth Heusler alloys with excellent physical properties, such as magnetic properties, half-metallic properties, ferromagnetic shape memory effect, magnetocaloric effect, ect. In this study, the alloy samples were prepared using a vacuum arc melting furnace, and the 873 K isothermal section of the Gd-Mn-Ga (≤50 at.%Ga) ternary alloy phase diagram was determined by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy spectrometry (EDS). The isothermal section consists of 22 single-phase regions, 44 two-phase regions, and 23 three-phase regions with the presence of 6 ternary compounds, GdMnGa, Gd2MnGa6, Gd2Mn15Ga2, Gd2Mn11Ga6, GdMn0.56Ga1.44, and GdMn0.37Ga1.63. The solid solubility ranges of Ga in β-Mn and Gd2Mn15Ga2 are 5.0–18.1 at.%Ga and 10.5–25.0 at.% Ga. The maximum solid solubility of Ga in α-Mn, GdMn12, and Gd6Mn23 are 2.0, 2.7, and 7.3 at.% Ga, respectively. The maximum solid solubility of Mn in GdGa2 is determined to be 13.1 at.% Mn.

Study on Electrical, Thermal, Magnetic Properties and Microstructure for - Al, -Al2Cu, ω-Al7Cu2Fe Phases in Al-32.5 wt. % Cu-1 wt. % Fe Ternary Alloy

The electrical properties of the Al-32.5 wt. % Cu-1 wt. % Fe ternary alloy were examined, it was observed that the electrical resistivity increased depending on the temperature and it was found as 6.8546x10-8 Ωm - 5.7780x10-7Ωm in the temperature range of 298-810K. The thermal conductivity was calculated using electrical measurement results and it was observed that it decreased depending on the temperature. The ternary alloy (cubic -Al, Fm-3m, 225 a = 4.0480 Å, -tetragonal Al2Cu, I4mcm, 140, a=6.0654 Å c=4.8732 Å, ω-tetragonal Al7Cu2Fe, P4 /mnc, 128, a = 6.3360 Å, m and c = 14.87 Å) phases were obtained. In this ternary alloy, phases were clearly seen in XRD studies and EDAX analyzes at room temperature. Magnetic properties such as magnetic transition temperature and magnetization curves of the alloy were determined.

Experimental study of the phase relations of the Fe–Pt–Ho ternary system at 500 °C

Abstract The phase relations of the Fe–Pt–Ho ternary system at 500 °C have been studied by using X-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy techniques. The Ho3Pt4 phase is stable at 500 °C, and the introduction of Fe does not cause the Ho3Pt4 phase to be decomposed into the two neighbouring phases HoPt and HoPt2. The single phase ranges of α-Fe, Fe3Pt, FePt, FePt3 and Pt in Fe–Pt binary system are from 0 to 10 at.% Pt, 14 to 32 at.% Pt, 33 to 63 at.% Pt, 66 to 78 at.% Pt, and 82 to 100 at.% Pt, respectively. The highest solid solubility of Ho in the α-Fe, Fe3Pt, FePt, FePt3 and (Pt, Fe) phases is less than 1.5 at.% Ho, 2 at.% Ho, 2 at.% Ho, 1.5 at.% Ho and 1.5 at.% Ho, respectively. The isothermal section at 500 °C of the Fe–Pt–Ho ternary alloy phase diagram has been constructed, which consists of 19 single-phase regions, 35 two-phase regions and 17 three-phase regions. No new ternary compounds were found.

In situ exsolution of ternary alloy nanoparticles from perovskite oxides to realize enhanced oxygen evolution reactivity

Perovskite oxides are promising electrocatalysts for oxygen evolution reaction (OER), while the rational modification on their surface may further improve the performance. Herein, through facile in situ exsolution, CoFeNi ternary alloy nanoparticles exsolved on Sr0.9Co0.5Fe0.35Ni0.15O3-δ (SCFN) parent with embedded and well-anchored structure is proposed as an excellent electrocatalyst for OER. The strong metal-perovskite interaction caused by the exsolution generates the unique synergistic coupling effect, activating the surface oxygen to achieve oxygen species (O22-/O-) and inducing abundant oxygen vacancies and multiple active sites. The electrocatalyst SCFN350, which was reduced in 10 % H2/Ar at 350 ℃ for 1 h, exhibits remarkable OER performance with an overpotential of 282 mV at a current density of 10 mA cm-2 in 1.0 M KOH electrolyte and good durability for 10 h in practical operation. The low Tafel slope (36.53 mV dec−1) and small charge transfer resistance (8.50 Ω) indicate its good charge transfer kinetics and electrical conductivity during OER. Our work not only reveals that a nanostructured ternary alloy phase can be exsolved from the perovskite matrix but also confirms that in situ exsolution is an effective strategy for designing OER catalysts.

Phase field modeling of precipitation in Zr-1%Nb-1%Sn alloy: a study of statistical properties and mechanical response

We develop the phase field model to simulate precipitation of secondary phase in ternary alloys with extra-small content of doping. This approach is applied to study β-phase precipitation in the model system of commercial alloy Zr-Nb-Sn at thermal treatment. An analysis of local rearrangement of doping and equilibrium vacancies during precipitation has shown that the dissolved Tin is mostly segregated around phase interface by trapping vacancies. Kinetics of precipitation, size and distribution of the precipitates, concentration of the species in precipitates and matrix are studied where it is revealed that Lifshits-Slyozov-Wagner distribution can be used to predicate statistical properties of precipitates. Mechanical response including the plastic deformations in precipitated solid is discussed. It is shown that yield strength change increases during precipitation. Yield and ultimate stresses are studied at different shear rates for the annealed alloy. A transition to plastic flow is described by means of dislocation structure evolution. Formation and growth of slip planes and dislocation loop-precipitate interaction governed by elastic moduli difference is analyzed. It is shown that emergence of dislocation loops around precipitates follows the Orowan mechanism.

Formation of diffusion micro-pairs in the Ni68Mo20Al12 alloy

• The sign of the nteratomic interaction in a binary alloy changes with temperature. • Chemical bonds (ionic and covalent) exist in both solid and liquid states of an alloy. • New phases in ternary alloys form inside of diffusion micro-pairs formed in liquid. The article presents the results of an electron microscopic study of the Ni 68 Mo 20 A l 12 alloy. The results got serve as the basis for the conclusion that the chemical bonds between atoms in ternary alloys are carried out according to the principle of pair interaction. These data show that the separation of the studied ternary alloy into diffusion micro-pairs occurs already in the liquid state. When the temperature of the alloy drops to 1200 °C in the Mo/A l diffusion pair, the “ordering-phase separation” transition occurs, and Mo atoms and A l atoms take part in the formation of diffusion pairs with nickel. The article concluded that the starting point for the formation of the microstructure of alloys is the liquid state in which any alloy is in the process of its smelting. It is noted that high-entropy alloys, in which such diffusion micro-pairs cannot be formed due to hindered diffusion of atoms, are unlikely to have prospects for their use in industry.

Stable hexagonal ternary alloy phase in Fe-Si-H at 28.6–42.2 GPa and 3000 K

Hydrogen (H) and silicon (Si) are considered as important light elements for the planetary cores. A large amount of H is able to alloy with pure Fe metal at high pressures. Si can also alloy well with Fe. However, it remains uncertain how much H can alloy with iron silicides and if it alloys how H can alter the crystal structures of Fe-Si alloys at high pressures-temperatures ($P\text{\ensuremath{-}}T$). We performed experiments on Fe-9Si and Fe-16Si alloys (9 and 16 wt % Si, respectively) in a H medium up to 42.2 GPa and 3000 K in diamond-anvil cells coupled with pulsed laser heating and gated synchrotron x-ray diffraction techniques. We found conversion of the Fe-Si alloys into Fe-rich (fcc and dhcp $\mathrm{Fe}{\mathrm{H}}_{x}$), Si-rich (B20 and B2 FeSi), and intermediate (${\mathrm{Fe}}_{5}{\mathrm{Si}}_{3}{\mathrm{H}}_{x}$) phases. The new ${\mathrm{Fe}}_{5}{\mathrm{Si}}_{3}{\mathrm{H}}_{x}$ phase has a structure similar to the hexagonal ${\mathrm{Fe}}_{5}{\mathrm{Si}}_{3}$ phase but with expanded volumes, and thus, possible H incorporation. Both the observed volume expansion and the H content estimated by density-functional theory calculations support a significant amount of H with H/Fe \ensuremath{\approx} 0.6 in the crystal structure. Because ${\mathrm{Fe}}_{5}{\mathrm{Si}}_{3}$ is known to break down above \ensuremath{\sim}1300 K at \ensuremath{\sim}18 GPa, our results suggest that hydrogen stabilizes the hexagonal structure at high $P\text{\ensuremath{-}}T$. These results have implications for the crystallization of Fe-rich liquid at the solid-to-liquid boundary of planetary cores and possible existence of chemical heterogeneities in the solid cores.

Mixing, Domains, and Fast Li-Ion Dynamics in Ternary Li–Sb–Bi Battery Anode Alloys

Both antimony and bismuth can alloy with up to three molar equivalents of lithium and are therefore attractive candidates for replacing graphite in Li-ion battery anodes. Li3Sb and Li3Bi have the same cubic structure (Fm3̅m), but the ternary Li–Sb–Bi system has not been studied. We synthesized Li3(SbxBi1–x) with different Sb mole fractions at room temperature by ball milling. These ternary alloys all have cubic crystal structures, as determined by X-ray diffraction (XRD), but show a tendency toward phase segregation for x = 0.25 and 0.50. For x = 0.25, the lattice parameter presents a clear positive deviation from Vegard’s law in XRD, while for x = 0.50, XRD reveals two phases after milling, with the Bi-rich minority phase diminishing after thermal annealing. Solid-state nuclear magnetic resonance spectroscopy provides evidence for a Sb-enriched environment around the Li atoms for Li3Sb0.25Bi0.75, and nuclear spin–lattice relaxation measurements of the binary and ternary alloy phases point to low activation energies and rapid Li-ion diffusion in Li3Bi.

Short-range order clusters in the long-period stacking/order phases with an intrinsic-I type stacking fault in Mg-Co-Y alloys

We have investigated short-range order (SRO) solute clusters in the long-period stacking/order (LPSO) phases with an intrinsic-I (I1) type stacking faults (SFs), which have been uniquely formed in Mg-Co-Y alloys, based on atomic-resolution scanning transmission electron microscopy (STEM) combined with first-principles calculations. The Co3Y5 SRO cluster model embedded across the I1-type SFs has been successfully constructed to satisfy the observed electron diffraction, STEM images and computed energetic stabilities. The optimized Co3Y5 cluster configurations appear to be significantly deviated from the host Mg atom positions and consequently provide a significant gain for the energetic stability of the I1-type LPSO phases. This is a similar phenomenon observed for the major LPSO phases with an intrinsic-II (I2) type SFs, and therefore the solute SRO clusters play an important key role for the formation and stability of the LPSO phases in ternary Mg alloys.

Short-Range Order Clusters in the Long-Period Stacking/Order Phases With an Intrinsic-I Type Stacking Fault in Mg-Co-Y Alloys

We have investigated short-range order (SRO) solute clusters in the long-period stacking/order (LPSO) phases with an intrinsic-I (I1) type stacking faults (SFs), which have been uniquely formed in Mg-Co-Y alloys, based on atomic-resolution scanning transmission electron microscopy (STEM) combined with first-principles calculations. The Co3Y5 SRO cluster model embedded across the I1-type SFs have been successfully constructed to satisfy the observed electron diffraction, STEM images and computed energetic stabilities. The optimized Co3Y5 cluster configurations appear to be significantly deviated from the host Mg atom positions and consequently provide a significant gain for the energetic stability of the I1-type LPSO phases. This is a similar phenomenon observed for the major LPSO phases with an intrinsic-II (I2) type SFs, and therefore the solute SRO clusters play an important key role for the formation and stability of the LPSO phases in ternary Mg alloys.

Annealing driven positive and negative exchange bias in Fe–Cu–Pt heterostructures at room temperature

We report the annealing-induced exchange bias in Fe–Cu–Pt based heterostructures with Cu as an intermediate layer (Fe/Cu/Pt heterostructure) and as a capping layer (Fe/Pt/Cu heterostructure). The exchange bias (shift in the hysteresis loop along the field axis) observed at room temperature (300 K) is found to be dependent on the annealing temperature. We obtained positive exchange bias of ∼ +120 Oe on annealing both the heterostructures at 400 °C, while on annealing these heterostructures at 500 and 600 °C a negative exchange bias of ∼ −100 Oe was observed. X-ray and polarized neutron reflectivity measurements show the evolution of the depth-dependent structure and magnetic properties of the heterostructures on annealing at different temperatures and revealed the coexistence of soft and hard (alloy) magnetic phases across the thickness of the films. Rapid and long-range interdiffusion at interfaces on annealing the systems at a temperature 〉 400 °C resulted into the formation of a ternary alloy phase. The observation of annealing-induced positive and negative exchange bias effect is dependent on the applied field and majority of the magnetic phase (hard/soft), present in the system. This annealing dependent coupling could give rise to more advanced applications of hard/soft ferromagnetic heterostructures.

Giant magneto resistance for CuCoNi granular films prepared by electrode position

CuCoNi granular films were prepared by electrodeposition, and the magnetoresistance were measured. The results show that the content of Ni is favorable for separation of more magnetic particles in the films. More Ni addition would decrease the concentration of magnetic particles. XRD analysis showed that the addition of Ni is in favor of magnetic particles of layer depositing. Excessive Ni added in the film but reduced concentration of magnetic particles. The layer complete phase separation after 600 °C annealing, corresponding to the copper diffraction peak intensity reaches the maximum; There is a clear satellite peaks at the between Co and Ni diffraction peak. Vacuum annealing make superparamagnetic particles into ferromagnetic particles, improve the coercivity. The GMR results show that 450 °C heat treatment to achieve the best film structure, with a maximum GMR, higher temperatures will form a ternary alloy phase in making the film, the GMR value is the lower.

Formation of phases in ternary substitution-interstitial alloys

The article discusses previously obtained results of experimental studies of multi-component alloys, in which all components are elements of substitution. It adduces the arguments that the formation of diffusion pairs in the liquid state of the alloy is the reason that causes the very possibility of the decomposition of multi-component substitution alloys. It is shown that in substitution-intеrstitial alloys such diffusion pairs are formed only between substitution atoms, the interstitial atoms do not participate in this process in view of their very high diffusion rate at high temperatures. Electron microscopic data obtained in the article show how the ternary Fe-22% Cr-1.1% N alloy decomposes when the temperature of its heating is reduced from the liquid state to the aging temperature.

The Application of CALPHAD Calculations to Uranium-Based Metallic Nuclear Fuels

The thermodynamic calculation and optimization on the binary and ternary systems consisting of Mo, Pu, Th, Ti, U, V and Zr used in metallic nuclear fuel are systematically reviewed. By combining the optimized systems in literatures and present assessment of U-Mo-Zr ternary system, the thermodynamic databases of U-Mo-based and U-Zr-based nuclear fuels were established based on the Calculation of Phase Diagram (CALPHAD) method. The stable phase diagrams and dynamical phase diagrams under irradiation were reviewed based on the database. As the examples for the application of the two thermodynamic databases, the effect of alloying elements on the stability of bcc (γU) phase in different ternary and multicomponent alloys were discussed, which can provide essential theoretical guidance for the design Uranium-based metallic nuclear fuels.

Metastable phase in binary and ternary 12-carat gold alloys at low temperature

Low temperature phase transitions in 12-carat gold alloys have been investigated for binary Au-Cu and ternary Au-Cu-Ag compositions. The thermal analyses investigations using differential scanning calorimetry (DSC) and the dilatometry were performed in the 50–300 °C temperature range in order to detect the structural transformations. The thermal analyses were carried out on annealed samples at 700 °C for two hour followed by water quenching. They reveal an important new reaction for both used compositions and both thermal techniques confirm each other. This reaction has been assessed as pre-ordering reaction. SEM and STM imaging were performed on annealed samples at 700 °C for two hours and water quenched followed by a heating from room temperature up to the temperature of the new peaks obtained in the thermal study. The imaging reveals the relationship between the pre-ordering reaction and the surface aspect presented in the fact of dendrite precipitates. A series of SEM observation have been performed in order to follow the kinetic of the observed precipitates by the way of several series of heating up, from 140 to 220 °C for the binary composition and from 100 to 180 °C for the ternary composition. Furthermore, this study shows that the silver accelerates the ordering reaction.

Radially Phase Segregated PtCu@PtCuNi Dendrite@Frame Nanocatalyst for the Oxygen Reduction Reaction.

Pt-based alloy nanoframes have shown great potential as electrocatalysts toward the oxygen reduction reaction (ORR) in fuel cells. However, the intrinsically infirm nanoframes could be severely deformed during extended electro-cyclings, which eventually leads to the loss of the initial catalytic activity. Therefore, the structurally robust nanoframe is a worthy synthetic target. Furthermore, ternary alloy phase electrocatalysts offer more opportunities in optimizing the stability and activity than binary alloy ones. Herein, we report a robust PtCuNi ternary nanoframe, structurally fortified with an inner-lying PtCu dendrite, which shows a highly active and stable catalytic performance toward ORR. Remarkably, the PtCu@PtCuNi catalyst exhibited 11 and 16 times higher mass and specific activities than those of commercial Pt/C.

Interfacial reaction and mechanical properties for Cu/Sn/Ag system low temperature transient liquid phase bonding

Low temperature transient liquid phase (LTTLP) bonding is a promising technology to enable in high temperature electronic packaging. In this study, interfacial reaction and mechanical characterizations for Cu/Sn/Ag system LTTLP bonding at temperatures ranging from 260 to 340 °C for various time were investigated. Experimental results showed that Cu and Ag substrate independently reacted with molten Sn, and the growth of IMCs on one side was hindered by the opposite IMCs layer after scalloped Cu6Sn5 contacted with the Ag3Sn, and there was no ternary alloy phase formed all the time. Pores were found and distributed at the Cu6Sn5/Ag3Sn interface or between grain boundaries after the residual Sn was fully consumed, however, they gradually disappeared with continuing reaction of that Cu6Sn5 phase converted into Cu3Sn phase. Shear strength of the LTTLP joints increased with increasing bonding time, and the adhesive strength of Cu6Sn5/Ag3Sn interface was weaker than that of the Cu3Sn/Ag3Sn interface. The rupture behaviors were also discussed with a fracture model. As follow, cracks initiated in the pore and mainly propagated along the Cu6Sn5/Ag3Sn interface for the joint consisted of layered Cu3Sn, Cu6Sn5 and Ag3Sn IMCs, however, failure path only passed through the Cu3Sn layer after Cu6Sn5 islands were completely transformed.

Microstructure and Thermal Analysis of As-Cast Ag-Bi-Ni alloys

The calculated liquidus projection of the Ag-Bi-Ni ternary system has been experimentally examined. Alloys were prepared by induction melting, and their microstructure studied by scanning electron microscopy coupled with energy dispersive x-ray spectroscopy. Of the primary solidification phases, (Ni) solidifies over the largest concentration range, although it was found to be narrower than calculated. The range in which Bi3Ni is the primary solidification phase was found to be broader than calculated. Also, the liquid miscibility gap is broader than predicted from assessed thermodynamic parameters. Differential thermal analysis was used to study temperatures of phase transitions of as-cast alloys, and recorded temperatures of melting of Bi3Ni and BiNi phases in ternary alloys agree well with those calculated.

Comparative assessment of synthetic strategies toward active platinum–rhodium–tin electrocatalysts for efficient ethanol electro-oxidation

The present work explores the effect of autoclave-based autogenous-pressure vs. ambient pressure conditions on the synthesis and properties of carbon-supported Pt–Rh–Sn nanoparticle electrocatalysts. The Pt–Rh–Sn nanoparticles were characterized by X-ray spectroscopy, electron microscopy and mass spectroscopy and deployed as catalysts for the electrocatalytic ethanol oxidation reaction. Pt–Rh–Sn catalysts precipitated with carbon already present showed narrow particle size distribution around 7 nm, while catalysts supported on carbon after particle formation showed broader size distribution ranging from 8 to 16 nm, similar metal loadings between 40 and 48 wt.% and similar atomic ratios of Pt:Rh:Sn of 30:10:60. The highest ethanol oxidation activity at low overpotentials associated with exceptionally early ethanol oxidation onset potential was observed for ambient-pressure catalysts with the active ternary alloy phase formed in presence of the carbon supports. In contrast, catalysts prepared under ambient pressure in a two-step approach, involving alloy particle formation followed by particle separation and subsequent deposition on the carbon support, yielded the highest overall mass activities. Based on the observed synthesis–activity correlations, a comparative assessment is provided of the synthetic techniques at high vs. low pressures, and in presence and absence of carbon support. Plausible hypotheses in terms of particle dispersion and interparticle distance accounting for these observed differences are discussed.

Effect of scandium addition on the microstructure, mechanical and wear properties of the spray formed hypereutectic aluminum–silicon alloys

Hypereutectic Al–x%Si–0.8Sc alloys (x=13, 16, 19 and 22wt%) were produced by spray forming. The microstructures of all the alloys exhibited very fine silicon phase with average size of about 5–10µm irrespective of the silicon content of the alloy. Transmission electron microscopy revealed the presence of a nano-scale scandium rich phase, identified as AlSi2Sc2 (V-phase) uniformly distributed in the alloy. The presence of V-phase resulted in higher matrix hardness (1.34GPa) in contrast to 1.04GPa observed in the case of binary Al–Si alloys by nanoindentation. Isothermal heat treatment at 375°C revealed insignificant coarsening of silicon phase in both binary and ternary alloys. The Al–x%Si–0.8Sc alloys exhibited higher flow stress and tensile strength in contrast to their binary alloy counterparts which was attributed to the bi-modal size distribution of the strengthening phases in the form of nano-scale V-phase and sub-micron to 10µm size silicon particles. The pin-on-disk wear tests exhibited appreciable improvement in the wear performance of the relatively low-silicon content ternary alloys over their binary counterparts while the high-silicon content binary and ternary alloys exhibited no much difference in the wear performance.