Ti Ternary System Research Articles

Phase equilibria and microstructure evolution of Al–Mo–Ti ternary alloys

Phase equilibria in Ti-lean part of the Al–Mo–Ti ternary system is investigated to understand the microstructure evolution of near-equi-atomic MoAl alloys containing Ti up to 17 at.%. A partial reaction scheme is proposed based on experimental study. A high temperature ternary A2(bcc)-β phase with Ti concentrations ranging from 13 to 17 at.% decomposes into A15 Mo 3Al–D0 22 Al 3Ti two-phase lamellar structure in a manner similar with a eutectoid reaction through a continuous cooling. The decomposition kinetics of the high temperature A2 phase is suppressed by adding Ti. Fine equi-axed two-phase structure is also obtained by an isothermal aging of a retained high temperature A2 phase.

The 500°C isothermal section of the Al–Dy–Ti ternary system

The phase relations in the Al–Dy–Ti ternary system at 500°C were investigated by powder X-ray diffraction (XRD), differential thermal analysis (DTA), optical microscopy and scanning electron microscopy (SEM) techniques. The existence of two ternary compounds DyTi2Al20 and Dy6Ti4Al43 were confirmed. The 500°C isothermal section of this ternary system consists of 14 single-phase regions, 27 two-phase regions and 14 three-phase regions. At 500°C, the maximum solid solubilities of Ti in Dy2Al, Dy3Al2 and DyAl2 is about 2.1at.%, 3.6at.%, 16.5at.%, respectively, and that of Dy in Ti, Ti3Al, TiAl is less than 1at.%.

The interaction of phosphorus with titanium and molybdenum

The interaction between the components in the ternary system Ti–Mo–P has been investigated using X-ray structure analysis. The isothermal section of the phase diagram at 1070 K has been built in the range 0–0.67 at.% phosphorus. Considerable solid solution ranges exist for the binary phosphides Ti 3P and Mo 3P. The solubility of the third component in the other binary compounds is insignificant. The existence of the earlier known ternary phosphide TiMoP 2 has been confirmed and a new compound (Ti,Mo) 12− x P 7 has been found to be exist in a concentration region described by the chemical formula Ti 7.1–4.5Mo 4.2–6.8P 7. The atomic parameters are refined by the full-profile Rietvelt method for a sample of the Ti 4.5Mo 6.8P 7 composition (space group P 6 , lattice parameters a=0.96834(3) and c=0.33091(1) nm, R=0.092). The crystal structure of the investigated phosphide is intermediate between the Cr 12P 7 and Zr 2Fe 12P 7 types.

ChemInform Abstract: The Isothermal Section of the Phase Diagram of the La—Ni—Ti Ternary System at 673 K.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The 573 K and 773 K isothermal sections of the phase diagram of the Pr–Ni–Ti ternary system

The 573 K and 773 K isothermal sections of the phase diagram of the Pr–Ni–Ti ternary system were investigated by X-ray diffraction, differential thermal analysis, optical microscopy and electron microscopy techniques. The 573 K isothermal section was restricted to the Pr-rich and Ti-rich parts of the Pr–Ni–Ti ternary system. The 773 K isothermal section was restricted to the Ni-rich part of the Pr–Ni–Ti ternary system. The (partial) 573 K isothermal section consists of 6 single-phase regions, 9 two-phase regions, and 4 three-phase regions. The (partial) 773 K isothermal section consists of 9 single-phase regions, 15 two-phase regions and 7 three-phase regions. The maximum solid solubilities of Ti in PrNi 2, PrNi 3, Pr 2Ni 7, PrNi 5, and Ni are about 2.5 at.% Ti, 1.5 at.% Ti, 1.0 at.% Ti, 2.0 at.% Ti, and 7.5 at.% Ti at 773 K, respectively. The solid solubilities of the other single-phase regions were too small to observe. The existence of any ternary compounds was not observed in the two partial ternary isothermal sections. The decomposition of NiTi was not observed in the Ni–Ti binary system or in the Pr–Ni–Ti ternary system.

Structural chemistry and phase relations in intermetallic systems Ti–{Pd,Pt}–Al

Phase relations in the ternary systems Ti–{Pd,Pt}–Al have been experimentally established for the partial isothermal sections at 950°C in the Pd/Pt-poor region (<25 at.% Pd/Pt). The investigation is based on X-ray powder diffraction, metallography, SEM and EMPA techniques on about 45 alloys, which were prepared by various methods employing arc melting, levitation melting under argon or by powder reaction sintering in closed crucibles. Three ternary compounds were observed at 950°C in the Ti–Pd–Al system: τ 3-(Ti,Pd)(Ti,Pd,Al) 2 with Laves-MgZn 2-type, τ 2-(Ti,Al) 6(Ti,Pd,Al) 23+1 with a filled Th 6Mn 23+1-type and τ 1-(Ti,Pd,Al)(Ti,Pd,Al) 3 with AuCu 3-type. Due to the wide extension of the Laves phase field, there is no compatibility among γTiAl and τ 2-(Ti,Al) 6(Ti,Pd,Al) 23+1. The Ti–Pt–Al system at 950°C contains three ternary compounds: τ 3-(Ti,Al)(Ti,Pt,Al) 2 with Laves-MgZn 2-type, τ 2-(Ti,Al) 6(Ti,Pt,Al) 23+1 with the filled Th 6Mn 23+1-type and τ 1-(Ti,Pt,Al) with Cu-type. Compatibility exists for Al-rich γTiAl and τ 2-(Ti,Al) 6(Ti,Pt,Al) 23+1. The typical feature for both alloy systems studied is the three-phase equilibrium: α 2Ti 3Al+γTiAl+τ 3-(Ti,Pd/Al)(Ti,Pd/Pt,Al) 2. The solid solubility of palladium and platinum in the binary titanium aluminides, as observed from EMPA and X-ray data, is rather small and at 950°C accounts to about 2.5 at.% Pd and 2.0 at.% Pt. Two new oxide compounds Ti 3PdAl 2O x and Ti 3PtAl 2O x with a filled Ti 2Ni-type are observed in both quaternary systems.

The isothermal section of the phase diagram of the La–Ni–Ti ternary system at 673 K

The isothermal section of the phase diagram of the ternary system La–Ni–Ti was investigated by X-ray diffraction, differential thermal analysis, optical microscopy and electron microscopy techniques. It consists of 14 single-phase regions, 25 two-phase regions and 12 three-phases regions. At 673 K, the maximum solid solubilities of Ti in Ni, LaNi 5, La 2Ni 7, LaNi 3, La 7Ni 16, and La 2Ni are about 6.0at% Ti, 2.5at% Ti, 3.0at% Ti, 3.2at% Ti, 3.2at% Ti, and 3.5at% Ti, respectively. The existence of any ternary compounds was not observed.

Phase formation and resistivity in the ternary system Ti–Nb–Si

We present measurements of the pseudobinary phase diagram of the TiSi2–NbSi2 system. This disilicide system has recently become important because of the enhanced formation of the low resistivity C54 phase of TiSi2 by addition of Nb. The solubility limit of Nb in C54 TiSi2 at 1000 °C is found to lie between 10% and 16% at the metal site, and the solubility limit of Ti in C40 NbSi2 at 1000 °C is between 76% and 79.5% at the metal site. Adding Nb to C54 TiSi2 increases the unit cell volume at a rate of 0.035% per at. % Nb. Adding Nb to C40 (Ti,Nb)Si2 increases the unit cell volume at a rate of 0.034% per at. % Nb. The presence of Nb enhances the formation of the C54 phase and improves its thermal stability. The desirable low resistivity of the C54 phase is increased by 1.2 μΩ cm per at. % Nb.

Thermodynamic modeling of the Nb–Si–Ti ternary system

A thermodynamic description of the Nb–Si–Ti ternary system is developed by modeling the Gibbs energies of the individual phases in the system. Due to insufficient experimental data, the ternary description is obtained primarily by extrapolation based on the descriptions of the constituent binary systems, i.e. Nb–Si obtained in this study, Ti–Si and Nb–Ti available in the literature. Nevertheless, the calculated ternary phase equilibria using the thermodynamic description so obtained agree very well with available experimental data, which suggests that the ternary description is reasonable. Although there might be large uncertainties involved in this description for alloy compositions far away from the Nb–Ti boundary binary, it can be very useful, in the absence of experimental data, as a guide for alloy design and processing development. Moreover, it can be used with great advantages in planning phase equilibrium measurements in the future and thus reduce the effort to be expended.

Phase Relation in the Titanium-Rich Region of the Ge&amp;ndash;Si&amp;ndash;Ti Ternary System

The Ti-rich region of the Ge-Si-Ti ternary isotherm at 900°C was determined by metallography, X-ray diffraction, and electron microprobe analysis. The sample alloys were prepared by arc-melting. It was confirmed that at 900°C Ti 5 Si 3 and Ti 5 Ge 3 form a continuous solid solution Ti 5 (Si 1-x Ge x ) 3 with the hP16 crystal structure. The lattice constants for Ti 5 (Si 1-x Ge x ) 3 are linear functions of the composition variable x. This continuous solid solution also exists at 1100°C. There is another solid solution Ti 3 (Si 1-y Ge y ), that has the same crystal structure as Ti 3 Si (tP32), but this solid solution is stable only for y<0.44 at 900°C. It was also shown that there is not any other binary or ternary phase within the Ti-Ti 5 Si 3 -Ti 5 Ge 3 triangular region except Ti 5 (Si 1-x Ge x ) 3 and Ti 3 (Si 1-y Ge y ). In this region, there is one three-phase field Ti+Ti 5 (Si 1-x Ge x ) 3 +Ti 3 (Si 1-y Ge y ), and the compositions of these three phases are Ti 0.96 Si 0.03 Ge 0.01 , Ti 0.63 Si 0.08 Ge 0.29 , and Ti 0.75 Si 0.14 Ge 0.11 respectively. In addition, there are three two-phase fields within this region: Ti 5 (Si 1-x Ge x ) 3 + Ti 3 (Si 1-y Ge y ), Ti+Ti 3 (Si 1-y Ge y ), and Ti+Ti 5 (Si 1-x Ge x ) 3 .

Nanocrystalline hard coatings within the quasi-binary system TiN–TiB2

Ti–B–N films with a gradient in the chemical composition were deposited onto austenitic stainless steel sheets by means of unbalanced DC magnetron co-sputtering using a segmented TiN\\Tib2 target. Film microstructure was characterized by means of electron-probe microanalysis (EPMA), transmission electron microscopy (TEM), electron energy-loss spectroscopy (EELS), and X-ray diffraction (XRD) as well as glancing angle X-ray diffraction (GAXRD). The mechanical properties of the coatings were measured using a depth-sensing nanoindenter. The composition of the films was found to lie close to the quasi-binary section TiN–TiB2 within the ternary system Ti–B–N. The grain size determined from TEM investigations range between 3 and 5 nm. Coatings consisted of a nanocrystalline fcc TiN phase (with boron atoms and oxygen impurities dissolved), and TiB2, TiB and B2O3. Microstructure as well as chemical composition of the films were not influenced significantly by the deposition parameters used in this investigation. Contrary, the mechanical properties were strongly influenced varying the ion bombardment. Hardness values exceeding 50 GPa and elastic moduli close to 500 GPa were obtained.

873 K Isothermal section of phase diagram for YFeTi ternary system

For Y-Fe-Ti ternary system, a ternary compound, Fe{sub 10.8}Ti{sub 1.2}Y, was observed by Mooij et al. in the alloys with composition Fe{sub 12{minus}x}Ti{sub x}y homogenized and equilibrated at 1123 K for 2--3 weeks. Additionally, a new ternary compound R{sub 3}(Fe,Ti){sub 29} (for R = Sm or Nd) has excited interest of research recently. The present work was also intended to determine whether or not this phase can exist for R = Y at the considered temperature range.

Alloys with the shape memory effect in systems of d-transition metals containing metals of the platinum group

Our own and literature data on the reactions in binary and ternary systems of transition metals, one component of which is a platinum group metal, and which contain phases which undergo a martensitic transformation, are reviewed. The transformation is responsible for the shape memory effect, which occurs in the alloys under consideration at temperatures above 300°C. In all equiatomic phases of the binary systems discussed (including quasibinary sections in the ternary systems Ti(Sc)–Ni(Co)–Me; Me=platinum group metal), in which the shape memory effect occurs, the transformation takes place from a matrix phase with a CsCl-type crystal structure. The properties of the parent and transformation phases, phase equilibria in the region of phase formation, and the effect of composition on these are described.

Local density functional calculations of the electronic structures ofTi2AlC and Ti3AlC

Local density functional calculations are used to address the electronic structures and the properties of chemical bonding of two definite phases formed within the ternary system Ti, Al and C: Ti 2 AlC and Ti 3 AlC. From the analyses of the density of states and of the crystal orbital overlap populations of the respective phases within the ASW method the role of C is assessed. Moreover, the bonding within TiC is discussed concomitantly. These calculations are of interest in the composite field to understand the mechanisms of formation of new compounds at the matrix/reinforcement interface.

Thermal Conductivity in &lt;I&gt;X&lt;/I&gt;&lt;SUB&gt;2&lt;/SUB&gt;&lt;I&gt;YZ&lt;/I&gt; Heusler Type Intermetallic Compounds

Results are given of comprehensive measurements on thermal conductivity of Heusler type intermetallic compounds Fe2AlTi, Co2AlTi, Ni2AlTi, Ni2GaTi, Ni2AlZr and Ni2AlHf. The compounds have fully ordered L21 structure. There exists a wide single phase region of L21 in Ni–Al–Ti ternary alloy system. The contour map showing the magnitude of thermal conductivity is constructed in Ni2AlTi single phase region. The thermal conductivity in Ni2AlTi takes a maximum of 21.4 Wm−1K−1 at stoichiometry which is much lower than that of NiAl having a B2 structure. By the deviation from stoichiometry, the thermal conductivity decreases in Heusler compounds. The magnitude of thermal conductivity in Fe2AlTi, Co2AlTi and Ni2AlTi are compared in connection with those of B2 aluminides (FeAl, CoAl, NiAl) and titanides (FeTi, CoTi, NiTi). Thermal conductivities in three kinds of Heusler compounds X2AlTi (X: Fe, Co, Ni) are almost the same value of approximately 20 Wm−1K−1. Ordering from B2 to L21 incrcases thermal conductivity in accord with the estimation by Nordheim relation. The magnitude of thermal conductivity in X2YZ Heusler compounds, including Ni2GaTi, Ni2AlZr and Ni2AlHf, is related to those of XY and XZ compounds having a B2 structure.

The structure and composition of TiZrN, TiAlZrN and TiAlVN coatings

In this paper, we deal with physically vapour-deposited hard coatings in the ternary system TiZrN and in the quaterrnary systems TiAlZrN and TiAlVN on various substrate materials such as cold-worked steels, high speed steels and cemented carbides. The reactive gas high performance sputtering technique has specific advantages in the deposition of these innovative complex coating materials with extremely different melting points because there is no intermediate liquid phase in the coating process. All the compound coatings investigated crystallize in a cubic face-centred TiN lattice with reduced or enlarged lattice parameters depending on the amount and type of the “foreign” atoms present. There was no real correlation found between wear properties, foreign metal type and content, and lattice distortion.

On the structure of (Ti, Al)N-PVD coatings

Thin films of the ternary system TiAlN, produced by PVD magnetron sputtering, show excellent wear-resistance and microhardness. It could be proved that a composition of the form (Ti, Al)N grows up a TiN lattice. Up in a 30 at.% aluminium can be solved in this lattice with decreasing lattice parameters. The ternary H-phase Ti 2AlN has not been deposited as the deposition temperatures are too low.

Transformations β → ω dans les alliages metalliques du systeme ternaire TiZrO

The X-ray study of the metallic alloys in the ternary system TiZrO shows the existence of phases α, β, ω (o) and of a new phase ω′ (o). This phase ω′ (o) appears in the alloy Ti 2ZrO after a long anneal at low temperature. Its structure is described in the space groupe Cmmm ( a = 4,8387 A ̊ ; b = 8,1486 A ̊ ; c = 6,1042 A ̊ ; 8 Ti atoms in 8 n with y = 0,338 and z = 0,254; 4 Zr atoms in 2 a + 2 d; 4 0 atoms in 4 e). The filiation of the phases shows the existence of ordering phenomena in the distribution of Ti and Zr atoms during the transformation β → ω (o), and in the distribution of 0 atoms during the transformation ω (o) → ω′ (o).

Some Superconducting Properties of Ti–Nb–Ta Ternary Alloys

Superconducting properties of the ternary system Ti–Nb–Ta were measured. Critical temperatures were found to decrease with increasing amount of Ta in the alloys from those of Ti–Nb binary alloys. However, a broad plateau of high critical fields (above 120 kG) was observed in the region around the composition 63 at.% Ti-31 at.% Nb-6 at.% Ta. This plateau is discussed in relationship with the corrected Abrikosov upper critical field and with the Maki upper critical field which includes the effects of Pauli paramagnetism and spin-orbit scattering. Critical current density data are also reported for one alloy.