Ti Ternary System Research Articles

A new composition zone of bulk metallic glass formation in the Cu–Zr–Ti ternary system and its correlation with the eutectic reaction

A new composition region of bulk metallic glass formation, around Cu 52Zr 40Ti 8, was discovered in the Cu–Zr–Ti ternary system, for which monolithic bulk metallic glass rods of 4 mm in diameter can be fabricated using copper mold casting. The solidification of the Cu 52Zr 40Ti 8 deeply-undercooled liquid mainly undergoes a univariant eutectic reaction, ( L → Cu 10Zr 7 + CuZr), even though this composition was predicted to be a ternary eutectic point ( L → Cu 10Zr 7 + CuZr + Cu 2ZrTi) by CALPHAD calculations. With respect to the deep-eutectic reaction of ( L → Cu 10Zr 7 + CuZr) in the Cu–Zr binary alloys, alloying of Ti has a significant effect on further stabilizing the liquid, as indicated as a drop of the univariant eutectic groove, limiting the coupled growth of two crystalline phases, hence increasing the glass-forming ability.

Cu−Zr−Ti ternary bulk metallic glasses correlated with (L → Cu8Zr3 + Cu10Zr7) univariant eutectic reaction

Starting from Cu60Zr30Ti10, the compositional dependence of bulk metallic glass (BMG) formation was revisited in the Cu−Zr−Ti ternary system. It was revealed that the optimal BMG-forming composition is located at Cu60Zr33Ti7, for which a monolithic BMG rod 4 mm in diameter can be fabricated using copper mold casting. This composition is along, although slightly off, the univariant eutectic groove for the reaction (L → Cu8Zr3 + Cu10Zr7). With respect to the corresponding Cu−Zr binary alloys, Ti has a significant effect on further stabilizing the liquid, thus increasing the glass-forming ability. For the Cu60Zr40−yTiy (3 ⩽ y ⩽ 10) series BMGs, the glass transition temperature Tg decreased with increasing Ti content, at a rate of about 2.8 K/at.%. Among these BMGs, significant compositional dependence of compressive plasticity is not observed, irrespective of the Tg change. Cu60Zr33Ti7 glass exhibits maximum fracture strength around 2160 MPa.

Microstructural and mechanical characterization of Nb-based in situ composites from Nb–Si–Ti ternary system

This study deals with the Nb–niobium silicide-based composites developed by the hot-pressing of Nb–Si–Ti ternary powder mixtures with a fixed Ti addition (6 at.%) and Si content ranging from hypereutectic (11 at.%) to near-eutectic compositions (18 at.%). The effects of Si content, Ti addition and strain rates on the sample microstructural characterization, flexural strength, fracture toughness, quasi-static compressive deformation and failure processes were investigated. It was revealed that the volume fraction of silicides increased with increasing Si content, and most of the Ti atoms dissolved into the niobium silicides to form (Nb,Ti) 5Si 3 solid solutions instead of binary titanium silicides. The experimental evidence showed that a moderate improvement in the flexural strength, fracture toughness and compressive yield stress of the composites was achieved by the addition of Ti. Higher Si additions produced a much more remarkable enhancement in the compressive yield stress and bulk hardness, whereas both the flexural strength and fracture toughness decreased with increasing Si content owing to the existence of residual porosities in the samples. The composites showed remarkable superiority to the arc-melted Nb–Si alloys and monolithic niobium silicides in fracture toughness ( 8.3 – 13.0 MPa m vs. 4.5 MPa m ), where the toughening effect was attributed mainly to crack bridging and crack deflection by the remaining ductile Nb phase. Moreover, quasi-static uniaxial compression tests at strain rates between 10 –5 and 10 –3 s −1 indicated that the deformation behavior and failure processes were significantly affected by Si content and strain rates. The strain-rate-hardening behavior for all the strain rates was observed in the composite materials and the strain-rate sensitivity decreased with increasing Si content. At a lower strain rate, the composite materials with a hypoeutectic Si composition failed with a pseudoplastic response and at an angle of ∼45° off the compressive loading direction. However, in the case of higher strain rate and Si content, the brittle failure in the samples occurred through vertical splitting and spalling of fragments.

Microstructure and mechanical properties of mechanically alloyed and spark plasma sintered amorphous–nanocrystalline Al 65Cu 20Ti 15 intermetallic matrix composite reinforced with TiO 2 nanoparticles

Multiphase Al 65Cu 20Ti 15 intermetallic alloy matrix composite, dispersed with 10 wt.% of TiO 2 nanoparticles, has been processed by mechanical alloying, followed by spark plasma sintering under pressure in the temperature range of 623–873 K. Differential scanning calorimetry and X-ray diffraction suggest that equilibrium crystalline phases evolve from the amorphous or intermediate crystalline phases. Transmission electron microscopy shows that the composite sintered at 873 K has partially amorphous microstructure, with dispersion of equilibrium, crystalline, intermetallic precipitates of Al 5CuTi 2, Al 3Ti, and Al 2Cu of 25–50 nm size, besides the TiO 2. The composite sintered at 873 K exhibits little porosity, hardness of 5.6 GPa, indentation fracture toughness in the range of 3.1–4.2 MPa√m, and compressive strength of 1.1 GPa. Indentation crack deflection by TiO 2 particle aggregates causes increase in fracture resistance with crack length, and suggests R-curve type behaviour. The study provides guidelines for processing high strength amorphous–nanocrystalline intermetallic composites based on the Al–Cu–Ti ternary system.

Bulk metallic glass formation in Cu–Zr–Ti ternary system

The formation of bulk metallic glasses (BMG) in the Cu-rich Cu–Zr–Ti ternary system is studied by using the ‘e/a-variant line criterion’. Three such lines, (Cu9Zr4)1−xTix, (Cu61.8Zr38.2)1−xTix and (Cu56Zr44)1−xTix, are defined in the Cu–Zr–Ti system by linking three binary compositions Cu9Zr4, Cu61.8Zr38.2 and Cu56Zr44 to the third element Ti. The binary compositions Cu9Zr4, Cu61.8Zr38.2 and Cu56Zr44 correspond to specific Cu–Zr binary clusters. BMGs are obtained by copper mould suction casting method with Ti contents of 7.5–15at.%, 7.5–12.5at.% and 5–12at.%, respectively along the (Cu9Zr4)1−x Tix, (Cu61.8Zr38.2)1−xTix and (Cu56Zr44)1−xTix lines. The BMGs on each composition line manifest decreased thermal stabilities and glass forming abilities (GFAs) with increasing Ti contents. The maximum GFA appears at Cu64Zr28.5Ti7.5, with characteristic thermal parameters of Tg=736K, Tx=769K, Tg/Tl=0.627 and γ=0.403, which are all superior to those reported for the known Cu60Zr30Ti10 BMG.

The metallic glass-forming region of a ternary metal system predicted by interatomic potential through molecular dynamics simulation

A scheme using molecular dynamics simulation is proposed to predict the glass-forming region (GFR) of a ternary metal system. Applying the proposed scheme, the GFR of the Ni–Hf–Ti ternary system is predicted to be an approximate quadrilateral region, the compositions of the four vertexes of which are determined to be Ni15Hf85Ti0, Ni15Hf0Ti85, Ni60Hf0Ti40 and Ni77Hf23Ti0, respectively. Importantly, the prediction from the proposed scheme matches well with the experimental observations and are in accordance with some proposed empirical rules.

Thermodynamic Analysis of Steels by Incorporating First-Principles Calculations into the CALPHAD Approach

A thermodynamic analysis of the Fe−M−P (M = Nb, Ti) ternary system has been performed by combining first-principles calculations with the CALPHAD approach. Because of the lack of experimental information available, thermodynamic properties of orthorhombic anti-PbCl2-type FeMP were evaluated using the Full Potential Linearized Augmented Plane Wave method, and the estimated values were introduced into a CALPHAD-type thermodynamic analysis. Applying this procedure, the phase diagrams of the Fe−M−P ternary phase diagrams whose contents are uncertain so far were calculated with a high degree of probability. Phase diagrams for high-purity ferritic stainless steels obtained following the same procedure are also presented.

Hemocompatibility of titanium-based coatings prepared by metal plasma immersion ion implantation and deposition

Metal plasma immersion ion implantation and deposition (MePIIID) has been proved to be an effective approach to enhance surface properties of various types of materials. In this work structure, phase composition, microhardness and surface properties, such as wettability and surface energy of layers of the ternary system Ti–N–O produced by MePIIID were investigated. To study the correlation between structure of coating and hemocompatibility the thrombocyte adhesion as well as the fibrinogen adsorption on the surface were measured. The blood compatibility of Ti oxide can be improved by the addition of nitrogen into the layer. The thrombocyte adhesion and fibrinogen adsorption were lower for TiNxOy than for TiO2. This correlates with a lower hydrophobicity and higher polar component of the surface energy for TiNxOy. The best hemocompatibility as well as the maximal microhardness have been found for the coating TiN0.4O1.6.

The isothermal section at 923 K of the Co–Cu–Ti ternary system measured by using diffusion triple

The isothermal section at 923 K in the Co–Cu–Ti system was experimentally studied by using the diffusion triple technique together with scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). High solubility of Cu, up to 22.5 at.% (substituting Co) in CoTi was observed at this temperature; and the solubility of Co (substituting Cu) in CuTi is also large which is up to 14.0 at.%. For other binary compounds CoTi 2, CuTi 2, Cu 4Ti 3 and Cu 3Ti 2, the ternary solubilities are remarkable too. No ternary compound has been detected. Nine three-phase equilibria were determined and three others in the Ti-enriched corner were estimated. Further investigations are essential to confirm the possible ternary phase reported and to determine the invariant reactions in the ternary system.

Determination of phase relations in the Co–Cu–Ti system by the diffusion triple technique

Two isothermal sections of the Co–Cu–Ti ternary system at 973 and 1123 K were experimentally determined using the diffusion triple technique together with scanning electron microscopy and electron probe microanalysis. The solubility of Cu (substituting Co) in CoTi increased from 22.8 at.% at 973 K to 28.1 at.% at 1123 K while that of Co (substituting Cu) in CuTi decreased from 11.1 to 8.8 at.% accordingly. In addition, the solubility limits of the third element in the binary compounds CoTi2, CuTi2, Cu4Ti3, and Cu3Ti2 were remarkable. Besides the solubility change, we found the Cu2Ti phase was stable at 1123 K but disappeared at 973 K. A ternary compound “m” with a composition range covering Co10Cu57Ti33 was detected at both isothermal sections. An invariant reaction Cu4Ti3 + CoTi ↔ CuTi + m at a temperature between 973 and 1023 K was deduced. Further investigations are necessary to confirm the reactions among Cu, Cu4Ti, Cu2Ti, Cu3Ti2, and “m” between 1023 and 1123 K.

The isothermal section of the Co–Cu–Ti ternary system at 1023 K by using diffusion triple technique

The isothermal section of the Co–Cu–Ti system at 1023 K was experimentally determined by using diffusion triple technique together with scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). Additional alloy samples annealed at 1023 K were analyzed to further confirm the results. Cu 2Ti was formed in diffusion couple and several alloy samples at 1023 K. Solubility of Cu in CoTi is 25.8 at.% (substituting Co), and that of Co (substituting Cu) in CuTi is 9.5 at.%. Other binary compounds such as CoTi 2, CuTi 2, Cu 4Ti 3 and Cu 3Ti 2 also have remarkable solubilities in ternary. And a ternary compound designated as “m” with a composition range covering Co 10Cu 57Ti 33 has been detected. With these results the 1023 K isothermal section has been established.

Thermodynamic description of the Ni–Si–Ti ternary system

Abstract A thermodynamic modeling of the Ni–Si–Ti system is conducted. All of the experimental phase diagram data available from the literature are critically reviewed and assessed using thermodynamic models for the Gibbs energies of individual phases. The thermodynamic parameters for five ternary compounds (τ1: Ti1Ni1Si1, τ2: Ti4Ni4Si7, τ3: Ti13Ni40Si31, τ4: Ti6Ni16Si7, and τ5: Ti2Ni3Si1), the ternary solution phases (liquid, bcc_A2, bcc_B2, fcc_A1, and L12) as well as the binary phases (Ti5Si3, Ni3Si, Ni5Si2, and TiNi3) showing noticeable solubilities for the third element are adjusted in the optimization. The order/disorder transitions between disordered bcc_A2 and ordered bcc_B2 phases as well as between disordered fcc_A1 and ordered L12 phases are treated using a two-sublattice model. The calculations indicate that the disordered and ordered phases can be described with a single equation. Comprehensive comparisons between the calculated and measured phase diagrams show that in the measured isothermal sections at 750°C, 900°C, 1000°C and 1100°C, most of the observed primary phase regions, as well as 16 out of the 26 experimentally observed invariant reaction temperatures are satisfactorily accounted for by the thermodynamic description. The liquidus projection and reaction scheme for the entire system are also presented. Further experimental work to solve a few discrepancies between calculation and experiment is emphasized.

The isothermal section of the Gd–Mn–Ti ternary system at 773 K

The isothermal section of the phase diagram of the Gd–Mn–Ti ternary system at 773 K has been investigated mainly by X-ray powder diffraction with the aid of differential thermal analysis. The 773 K isothermal section of the ternary system consists of 11 single-phase regions, 19 two-phase regions and 9 three-phase regions. At 773 K, the maximum solid solubility of Ti in Mn, GdMn 12, Gd 6Mn 23 and GdMn 2 are about 8, 2, 3 and 3 at% Ti, respectively. The homogeneity range of Mn 2Ti extends from about 61 to 69 at% Mn. No ternary compounds were observed in this system.

The isothermal section of the phase diagram of the Dy–Mn–Ti ternary system at 773 K

The isothermal section of the phase diagram of the Dy–Mn–Ti ternary system at 773 K has been investigated mainly by X-ray powder diffraction (XRD), differential thermal analysis (DTA) and optical microanalysis techniques. It consists of 11 single-phase regions, 19 two-phase regions and 9 three-phase regions. At 773 K, the maximum solid solubility of Ti in Mn, DyMn 12, Dy 6Mn 23 and DyMn 2 are about 8, 3, 3.5 and 3.5 at% Ti, respectively. The homogeneity range of Mn 2Ti extends from about 61–69 at% Mn. No ternary compounds were observed in this system.

Thermodynamic Analysis of the Phase Equilibria of the Nb–Ni–Ti System

A thermodynamic analysis of the Nb–Ni–Ti system has been performed following the CALPHAD technique. To enable the thermodynamic description of the binary systems, the results from a previous evaluation were adopted for the Nb–Ni, Nb–Ti, and Ni–Ti systems. However, a slight modification of the parameters was applied to the bcc and Nb6Ni7 phases in the Nb–Ni system, when considering the ternary phase equilibria. The phase boundaries of the Nb–Ni–Ti ternary system at a constant 28 mol%Ni and 60 mol%Ni were determined experimentally by differential scanning calorimetry. A thermodynamic assessment of the ternary system was performed based on the experimental information as well as the reported phase boundaries of the isothermal sections of the Nb–Ni–Ti system at 700, 800, and 900 � C. Our calculations reveal that this system includes 15 types of ternary invariant reactions. The ternary eutectic temperature was between 901.6 and 1063.7 � C.

The 500 °C Isothermal Section of the Nd—Al—Ti Ternary System.

AbstractFor Abstract see ChemInform Abstract in Full Text.

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

The phase relations in the Nd–Al–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 NdTi 2Al 20 and Nd 6Ti 4Al 43 were confirmed. The isothermal section of this ternary system consists of 15 single-phase regions, 29 two-phase regions, and 15 three-phase regions. At 500 °C, the maximum solid solubilities of Ti in Nd 3Al, Nd 2Al, and NdAl 2 is about 2.4, 3.5, and 16.1 at.%, respectively, and that of Nd in Ti, Ti 3Al, TiAl is less than 1 at.%.

The 773 K Isothermal Section of the Ternary Phase Diagram of the Nd—Ni—Ti.

Abstract The isothermal section of the phase diagram of the Nd–Ni–Ti ternary system at 773 K has been investigated by X-ray powder diffraction, DTA, optic microscopy and scanning electron microscopy techniques. It consists of 13 single-phase regions, 23 two-phase regions and 11 three-phase regions. At 773 K, the maximum solid solubilities of Ti in Ni, NdNi 5 , Nd 2 Ni 7 , NdNi 3 and NdNi 2 are about 7, 3, 3, 3 and 2 at.% Ti, respectively. The existence of any ternary compounds was not observed.

Mapping of the Nb–Cr–Ti phase diagram using diffusion multiples

Abstract A high-efficiency diffusion-multiple approach was employed to map the phase diagram of the Nb–Cr–Ti ternary system which is critical for the design of niobium silicide-based composites. These composites have high potential as a replacement for Ni-base superalloys for jet engine applications. The formation of the Laves phase and alloying with Ti are critical for the high oxidation resistance of the composites and the Nb–Cr–Ti system serves as the base for understanding the Laves phase formation and Ti alloying. Three isothermal sections at 1000, 1150 and 1200 °C were constructed from the results obtained from diffusion multiples using scanning electron microscopy, electron probe microanalysis, and electron backscatter diffraction. The results help to define the relative stability of the C15 and C36 Laves phases in the Nb–Cr–Ti ternary system.

The 773 K isothermal section of the ternary phase diagram of the Nd–Ni–Ti

The isothermal section of the phase diagram of the Nd–Ni–Ti ternary system at 773 K has been investigated by X-ray powder diffraction, DTA, optic microscopy and scanning electron microscopy techniques. It consists of 13 single-phase regions, 23 two-phase regions and 11 three-phase regions. At 773 K, the maximum solid solubilities of Ti in Ni, NdNi 5, Nd 2Ni 7, NdNi 3 and NdNi 2 are about 7, 3, 3, 3 and 2 at.% Ti, respectively. The existence of any ternary compounds was not observed.