The Fe–Ni–Al phase diagram in the Al-rich (>50 at.% Al) corner

The ternary Fe–Ni–Al phase diagram between 50 and 100 at.% Al was investigated by a combination of powder X-ray diffraction (XRD), differential thermal analysis (DTA) and electron probe microanalysis (EPMA). Ternary phase equilibria and accurate phase compositions of the respective equilibrium phases were determined within the isothermal section at 850 °C. The crystal structure of τ1 (Fe_4−xNi_xAl₁₀) and τ2 (Fe_2−xNi_xAl₉) was determined by means of single crystal X-ray diffraction. The decagonal quasi-crystalline phase q (Fe_4.9Ni_23.4Al_71.7) was found to be stable between 850 °C and 930 °C. All experimental data were combined to yield a ternary reaction scheme (Scheil diagram) involving 10 ternary invariant reactions in the investigated composition range, and a liquidus surface projection was constructed based on DTA results.     

Structure and phase-composition of Ti-doped gas atomized Raney-type Ni catalyst precursor alloys

Raney-type Ni precursor alloys containing 75 at.% Al and doped with 0, 0.75, 1.5 and 3.0 at.% Ti have been produced by a gas atomization process. The resulting powders have been classified by size fraction with subsequent investigation by powder XRD, SEM and EDX analysis. The undoped powders contain, as expected, the phases Ni₂Al₃, NiAl₃ and an Al-eutectic. The Ti-doped powders contain an additional phase with the TiAl₃ DO₂₂ crystal structure. However, quantitative analysis of the XRD results indicate a far greater fraction of the TiAl₃ phase is present than could be accounted for by a simple mass balance on Ti. This appears to be a (Ti_xNi_1−x)Al₃ phase in which higher cooling rates favour small x (low Ti-site occupancy by Ti atoms). SEM and EDX analysis reveal that virtually all the available Ti is contained within the TiAl₃ phase, with negligible Ti dissolved in either the Ni₂Al₃ or NiAl₃ phases.     

Experimental Investigation of Phase Equilibria in the Ni-Cr-Si Ternary System

Phase equilibria of the Ni-Cr-Si ternary system at 1000 and 1100 °C have been experimentally investigated by means of electron probe microanalyzer (EPMA) and x-ray diffraction (XRD) analysis on the equilibrated alloys. In the present work, the existence of the ternary compounds of σ (Cr₁₃Ni₅Si₂), π (Cr₃Ni₅Si₂), τ₁ (Cr₂Ni₂Si) and τ₂ (Cr₃Ni₃Si₄), at both 1000 and 1100 °C is confirmed. The binary γ (Ni₃₁Si₁₂), δ (Ni₂Si), and CrSi phases exhibit a considerable solubility of a third element. Additionally, a liquid phase region is found at 1100 °C in the ranges of 15.5-21.3 at.% Cr and 22.1-25.1 at.% Si.     

Structure and magnetic properties of Cu-Ni alloy nanoparticles prepared by rapid microwave combustion method

Cu-Ni alloy nanoparticles were prepared by a microwave combustion method with the molar ratios of Cu²⁺ to Ni²⁺ as 3:7, 4:6, 5:5, 6:4 and 7:3. The as-prepared samples were characterized by XRD, HR-SEM, EDX and VSM. XRD and EDX analyses suggest the formation of pure alloy powders. The average crystallite sizes were found to be in the range of 21.56–33.25 nm. HR-SEM images show the clustered/agglomerated particle-like morphology structure. VSM results reveal that for low Ni content (Cu₅Ni₅, Cu₆Ni₄ and Cu₇Ni₃), the system shows paramagnetic behaviors, whereas for high Ni content (Cu₃Ni₇ and Cu₄Ni₆), it becomes ferromagnetic.     

Phase equilibria and structural investigations of the general NiAs-type in the ternary system Ni–Sn–Te

The ternary system Ni–Sn–Te was investigated by means of light optical microscopy (LOM), powder X-ray diffraction (XRD), differential thermal analysis (DTA) and scanning electron microscopy (SEM) in combination with energy dispersive X-ray spectroscopy (EDX). Two isothermal sections at 600 and 800 °C were investigated experimentally. The two ternary compounds, Ni_5.78SnTe₂ (space group I4/mmm, Pearson symbol tI18) and Ni_3−xSnTe₂ (space group P6₃/mmc, Pearson symbol hP12), already known from literature, were confirmed, although Ni_3−xSnTe₂ was found only at 600 °C. At higher temperatures a continuous phase field of the general NiAs-type structure was discovered between NiTe_2−x and Ni₃Sn₂ HT. It ranges continuously from 34 to 63 at.% Ni, covering CdI₂-types, as well as Ni₂In-type domains; thus a continuous transition from the CdI₂ to Ni₂In type is confirmed, to the best of our knowledge, for the first time. Lattice parameter variations and the transition CdI₂–NiAs–Ni₂In in the ternary phase field were analysed.Furthermore, vertical sections at 10, 40, 55, 60 and 70 at.% Ni were determined. A liquidus surface projection and a reaction scheme of the system were constructed as well. Altogether, 17 invariant phase reactions, including 3 eutectic reactions, 2 peritectic reactions, 11 transition reactions and one maximum were discovered.     

The Al–Ni–Si phase diagram—Part III: Phase equilibria in the nickel rich part

The ternary Al–Ni–Si phase diagram between 66.7 and 100 at.% Ni was investigated by a combination of differential thermal analysis (DTA), powder X-ray diffraction (XRD), metallography and electron probe microanalysis (EPMA). The ternary phase equilibria were analyzed within the isothermal section at 1000 °C, and DTA was used to determine the various invariant reactions within the three sections at 70, 75 and 80 at.% Ni. A liquidus surface projection was constructed for the entire composition range by combining our experimental data with those from literature. Powder XRD was used to determine the lattice parameters and their variation as a function of composition for the solid solutions. Based on our analysis, we report the existence of two major solid solution phases, namely, (a) the solid solution of Al and Si in Ni and (b) the complete solid solution between the isostructural binary compounds AlNi₃ (γ′) and Ni₃Si (β₁).     

Experimental investigation on the phase equilibria of the Mn–Ni–Zn system at 400 °C

Partial isothermal section of the Mn–Ni–Zn system at 400 °C was experimentally established by means of XRD and SEM/EDS techniques. Three ternary compounds, i.e. T, τ₁ and τ₂, were found to exist at 400 °C for the first time. The compound T having an approximate formula of Mn₇Ni₇Zn₈₆ was indexed as fcc structure with a lattice parameter of a = 1.81476 (1) nm. τ₁, the structure of which is unknown, has an approximately stoichiometric composition of about 29 at.% Mn, 38 at.% Ni and balanced Zn. τ₂ has fcc structure and a composition range of about 46–40 at.% Mn and constant 30 at.% Zn. Extended single-phase regions of the phases Mn₅Zn₂₁, Ni₂Zn₁₁, NiZn₃, NiZn and β-Mn were observed. The maximum solubility of Ni in Mn₅Zn₂₁ and those of Mn in Ni₂Zn₁₁, NiZn₃ and NiZn were determined to be 10, 6, 26 and 25 at.% at 400 °C, respectively.     

The constitution of the ternary system Fe–Ni–Si

The ternary system Fe–Ni–Si was investigated using X-ray diffraction (XRD), metallography (SEM), energy dispersive spectroscopy (SEM/EDS), magnetic susceptibility measurements, and differential thermal analysis (DTA). The existence of the ternary phase τ is corroborated and its crystal structure is confirmed to be isostructural to Cr₃Ni₅Si₂. At 700 °C the homogeneity of this phase extends from 43 to 55 at.% iron at constant 20 at.% Si. Furthermore, for the binary phases NiSi₂, Ni₂Si and Ni₃₁Si₁₂ extensive solubilities for iron are found, while the solubility of Fe in NiSi, Ni₃Si₂ or Ni₃Si does not exceed 5 at.%. On the other side of the system, the phases FeSi and Fe₃Si have large solubilities for Ni, while this is rather limited in FeSi₂. The (binary high temperature) phase Fe₅Si₃ is stabilized by Ni at least down to 700 °C. Tie lines exist between τ and solid solutions based on Fe₃Si, Ni₃₁Si₁₂ as well as γ (Ni). DTA measurements for the vertical section Fe₂Si–Ni₂Si strongly indicate that Fe₂Si and θNi₂Si form a complete series of solid solutions θ(Fe, Ni)₂Si and are thus isostructural. A critical evaluation of the available crystal structure data for Fe₂Si supports this assumption. Iron rich θ(Fe, Ni)₂Si is a weak ferromagnet. The magnetic moment of ～1 μB per Fe-atom in θ(Fe, Ni)₂Si is only half of the magnetic moment per Fe-atom measured for τ Fe₅Ni₃Si₂. A reaction scheme accounting for all DTA data of the entire system is established and in combination with observations on the first crystallizing phase(s) the liquidus surface of Fe–Ni–Si is revised.     

Microstructural characteristic of NiTi coating on stainless steel by plasma transferred arc process

In this study, NiTi powder mixture was coated on the surface of an austenitic stainless steel (AISI 304) by plasma transferred arc (PTA). Coating was carried out by using 80, 90, 100 A current density under Ar atmosphere. Coating layer and interface were examined with SEM, EDX, XRD analysis and micro hardness test. Thickness of coating increased with current density. No cracks or pores were detected in the interface. Higher arc current densities caused a coating layer poor in NiTi alloy. Secondary phases such as Cr₂Fe₇Ni, Fe₇Cr₂Ni and Ni₃Ti also formed in the coating layer.     

Thermodynamic study of phase equilibria in the Ni-Si-B system

A thermodynamic analysis of the phase equilibria in the Ni-Si-B ternary system was conducted. A regular solution approximation based on a sublattice model was adopted to describe the Gibbs energies for the individual phases in the binary and ternary systems. A set of thermodynamic parameters for the individual phases was evaluated from literature data on phase boundaries and thermochemical properties. The optimized parameters reproduced the experimental data, for the most part, satisfactorily. However, in the calculated isothemal section at 850 °C, phase equilibria between the fcc phase and Ni₆Si₂B or Ni₃Si(β ₁) and Ni₆Si₂B were found instead of the experimentally observed equilibria between Ni₃Si(β ₁) and Ni₃B or Ni₅Si₂(γ) and Ni₃B. Further, in the primary crystal surface for the fcc phase, the calculated liquidus temperatures were higher than the reported values by approximately 80 °C. Therefore, it is considered that the fcc phase evaluated in the Ni-Si system by Lindhólm and Sundman is too stable.     

Thermodynamic study of phase equilibria in the Ni-Si-B system

A thermodynamic analysis of the phase equilibria in the Ni-Si-B ternary system was conducted. A regular solution approximation based on a sublattice model was adopted to describe the Gibbs energies for the individual phases in the binary and ternary systems. A set of thermodynamic parameters for the individual phases was evaluated from literature data on phase boundaries and thermochemical properties. The optimized parameters reproduced the experimental data, for the most part, satisfactorily. However, in the calculated isothemal section at 850 °C, phase equilibria between the fcc phase and Ni₆Si₂B or Ni₃Si(β ₁) and Ni₆Si₂B were found instead of the experimentally observed equilibria between Ni₃Si(β ₁) and Ni₃B or Ni₅Si₂(γ) and Ni₃B. Further, in the primary crystal surface for the fcc phase, the calculated liquidus temperatures were higher than the reported values by approximately 80 °C. Therefore, it is considered that the fcc phase evaluated in the Ni-Si system by Lindhólm and Sundman is too stable.     

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.     

Measurement of 900 °C Isothermal Section in the Mo-Ni-Zr System

The isothermal section of the Mo-Ni-Zr system at 900 °C was investigated by characterization of eighteen equilibrium alloys. Electron probe microanalysis (EPMA) and x-ray diffraction (XRD) were used to identify the phases and obtain their compositions. The existence of two ternary compounds, Zr₆₅Mo_18?x Ni_16.5+x (τ₁, cF96-Ti₂Ni) and Zr₆₅Mo_27.3Ni_7.7 (τ₂, hP28-Hf₉Mo₄B), was confirmed in the Zr-rich corner, and the compositions of the two phases were determined. The isothermal section of the Mo-Ni-Zr system at 900 °C consists of 15 three-phase regions and 29 two-phase regions. The following three-phase equilibria were well established: (1) (Ni) + Ni₇Zr₂ + Ni₅Zr, (2) MoNi + MoNi₃ + Ni₇Zr₂, (3) Ni₇Zr₂ + MoNi + (Mo), (4) (Mo) + Ni₇Zr₂ + Ni₃Zr, (5) (Mo) + Ni₃Zr + Ni₂₁Zr₈, (6) (Mo) + Ni₂₁Zr₈ + Ni₁₀Zr₇, (7) (Mo) + Ni₁₀Zr₇ + NiZr, (8) (Mo) + Mo₂Zr + NiZr, (9) NiZr₂ + Mo₂Zr + τ₁, (10) τ₁ + Mo₂Zr + τ₂, (11) τ₂ + Mo₂Zr + (Zr)ht, (12) NiZr₂ + τ₁ + (Zr)ht and (13) τ₁ + τ₂ + (Zr)ht. Several binary phases, such as MoNi₃, Ni₇Zr₂ and Mo₂Zr, dissolve appreciable amount of the third component.     

Phase equilibria in the Fe–Al–Nb system: Solidification behaviour,liquidus surface and isothermal sections

The Fe–Al–Nb phase diagram including isothermal sections at 1000, 1150, and 1300 °C as well as the liquidus surface and corresponding reaction scheme was studied experimentally by a combination of scanning electron microscopy (SEM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and differential thermal analysis (DTA). No genuinely ternary intermetallic phase exists in the system, but the two Fe–Nb phases NbFe₂ (C14-type Laves phase) and Fe₇Nb₆ (μ phase) have extended homogeneity ranges in the ternary system, where large amounts of Fe can be substituted by Al in both cases. The solubility of the third element was studied for all binary phases and the effect on the lattice parameters is discussed. From analysis of the as-cast microstructures and DTA experiments, the liquidus surface including all invariant reactions as well as the occurring solid state reactions were established. Three ternary eutectics, one eutectoid, and two peritectic reactions were found, and the list of invariant points is completed by seven U-type reactions.     

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.     

Influence of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Particle Size on Microstructure,Mechanical Properties and Abrasive Wear Behavior of Flame-Sprayed and Remelted NiCrBSi Coatings

The influence of micrometric alumina (low surface area-to-volume ratio) and nanometric alumina (high surface area-to-volume ratio) on microstructure, hardness and abrasive wear of a NiCrBSi hardfacing alloy coating applied to an AISI 304 substrate using flame spraying (FS) combined with surface flame melting (SFM) is studied. Remelting after spraying improved the mechanical and tribological properties of the coatings. Microstructural characterization using XRD, SEM and EDS indicated that alumina additions produced similar phases (NiSi, Ni₃B, CrC and Ni₃₁Si₁₂) regardless of the alumina size, but the phases differed in morphology, size distribution and relative proportions from one coating to another. The addition of 12 wt.% nanometric Al₂O₃ increased the phases concentration more than five- to sixfold and reduced the hard phases size about four-to threefold compared with NiCrBSi + 12 wt.% micrometric Al₂O₃. Nanoalumina led to reduced mass loss during abrasive wear compared to micrometric alumina and greater improvement in hardness.     

The Fe-A1-Ti system

An extensive experimental investigation of the Fe-Al-Ti system by metallography, microprobe analysis, and XRD on quenched specimens and on diffusion couples is presented. Two isothermal sections at 800 and 1000 °C were established; they differ substantially from the existing (800 °C) or partly determined (1000 °C) diagrams. From these results, existence of the τ₁ phase (Fe₂AlTi) can be ruled out. Existence of the ternary compounds, τ₂ (Al₂FeTi) and τ₃ (Al₂₂Fe₃Ti₈), is confirmed. The composition limits of both phases were determined; they differ considerably from those given in earlier reports. The τ₂ phase apparently exists in a cubic and a tetragonal polymorph, depending on composition. The cubic form exists at high titanium contents. At 1000 °C, the two polymorphs are separated by a miscibility gap. At compositions where the “X phase” (Al₆₉Fe₂₅Ti₆) was previously reported, single-phase samples were obtained at both temperatures. From the present results, there is no evidence to assume that this is a new ternary phase rather than the ternary homogeneity range of the Al₃Fe phase. In addition, extensions of the binary intermetallic phases into the ternary system were determined.     

Experimental Phase Diagram Investigations in the Ni-Rich Part of Al-Fe-Ni and Comparison with Calculated Phase Equilibria

The phase equilibria in the section Ni₃Fe-Ni₃Al and phase boundaries of γ′(Ni₃Al) at 1000 °C were studied by a combination of powder X-ray diffraction (XRD), differential thermal analysis (DTA), and electron probe microanalysis (EPMA). The existence of a continuous solid solution at 450 °C was confirmed by a linear decrease of the lattice parameter from Ni₃Al to Ni₃Fe. The phase boundaries of γ′ with γ and the B2-type phase were determined at 1000°C by EPMA. A vertical section of the phase diagram from Ni₃Al to Ni₃Fe above 450 °C, including the liquidus temperatures, is proposed based on the DTA investigations. The invariant four-phase equilibrium U: L + γ′ = γ + B2 is found to occur at 1366 ± 1 °C. The experimental data are compared with a calculated phase diagram obtained by extrapolation from the corresponding binary data sets.