Ti In Cu Research Articles

The influence of Ti: Si3N4 ratio on the microstructure evolution of Ti–Si3N4 reaction in Cu melts

In this work, through the study of the obtained Cu–Ti–Si–N intermediate products by controlling the reaction degree of Ti and Si3N4 powder in Cu melts at 1250∼1300 °C, the effects of different Ti: Si3N4 mass ratios on the microstructure evolution of Ti–Si3N4 reaction in Cu melts were verified. When the mass ratio of Ti: Si3N4 is higher, such as 3.09:1, TiN will cooperate with Ti5Si3 and depend on each other to nucleate and grow to form TiN/Ti5Si3 composites. The formed TiN are spherical and wetted by Ti5Si3 to uniformly disperse in Cu melts. As a result, the TiN–Ti5Si3 hybrid reinforced Cu matrix composites will be formed. However, when the mass ratio of Ti: Si3N4 is lower, such as 1.37:1, Ti and Si3N4 will firstly react to form TiN and Ti–Si liquid. The formed TiN are irregularly polygonal and connect with each other. The Ti–Si liquid will combine with Cu melts to form Cu–Ti–Si liquid and finally form δCu4Si, ηCu3Si and τ1-CuSiTi phases during the colling stage. In this case, TiN are difficult to be wetted, and the Ti–Si3N4 compact will keep its original shape and not spread in Cu melts.

The introduction of SiC into Cu melts based on Ti–SiC system and its transformation

In this work, SiC particles with different sizes have been effectively introduced into Cu melts based on Ti–SiC system, and the types and microstructures of Ti–SiC reaction products are varied with the SiC size change. With small size, SiC can absolutely react with Ti to form TiC particles and Ti5Si3, while large SiC cannot react completely. In the latter case, besides TiC particles and Ti5Si3, the core–shell particles, including Cu@TiC, SiC@TiC, carbon derived from silicon carbide (SiC-CDC) @TiC and ternary layers SiC@SiC-CDC@TiC, can be formed. It is considered that the reaction of Ti–SiC in Cu melts not only has two alternative reaction path ways but also has two stages. The first stage is the instantaneous reaction between Ti and SiC during the addition and start with TiC formation, which realizes the reactive wetting of SiC by Cu melts and leads to the eventual formation of TiC or SiC@TiC core–shell particles. The second stage is the reaction between Ti and residual SiC in Cu melts which starts with the transformation of SiC into SiC-CDC and leads to the eventual formation of Cu@TiC, SiC-CDC@TiC or SiC@SiC-CDC@TiC core–shell particles.

Neutron activation analysis of meteorites at the VR-1 training reactor

Samples of space objects were characterized using instrumental neutron activation analysis (NAA) combined with conversion electron Mössbauer spectrometry. Fragments of Moldavites, Muonionalusta meteorite and Sikhote-Alin meteorite were irradiated in the thermal neutron field of the low-power VR-1 training reactor operated by the Czech Technical University in Prague. Activated samples were investigated by means of nuclear gamma-spectrometry technique (semiconductor HPGe detector). Qualitative analysis revealed the occurrence of Na, Al, Mg, Cl, K, Ti, V, Mn, Fe, Sr, and Ba in Moldavites, Na, Cl, Mn, Fe, Co, Cu, Ni, As, and Au in Muonionalusta iron meteorite, and Ni, Co, Fe, and Mn in Sikhote-Alin iron meteorite. Employing the comparative NAA, the concentration of Na, Al, K, Ti, V, Fe, and Sr in Moldavite, concentration of Na, Fe, Ni, and Au in Muonionalusta meteorite, and concentration of Ni in Sikhote-Alin meteorite was determined. Moreover, Muonionalusta meteorite structure was investigated using the conversion electron Mössbauer spectrometry at room temperature, and α-(Fe, Ni) phase and γ-(Fe, Ni) phase were identified. The obtained results clearly show that the low-power VR-1 research reactor (80 W) is an excellent tool for NAA experiments, and that nuclear-analytical techniques can provide useful data for other scientific branches.

Wetting of liquid copper on TC4 titanium alloy and 304 stainless steel at 1273–1433 K

The wetting behaviour of pure copper on the surface of TC4 titanium alloy and 304 stainless steel plates was studied by the sessile drop method at temperatures of 1273–1433 K under high vacuum. The FeO oxide film limited the solid/liquid interfacial mass transfer in a Cu/304ss system, but the TiO oxide film was not a limiting factor in a Cu/TC4 system. The potential spreading model was judged by the Rn-t relationship, in which n was close to 4 in a Cu/TC4 system, which confirmed the presence of diffusion-limited wetting. For Cu/304ss, 4 ≤ n ≤ 10: this indicated behaviour between that of the diffusion-limited reactive control model and the hydrodynamic model. At the Cu/304ss joining side, the wetting activation energy (55.1 kJ/mol) corresponded to the sum of the diffusion activation energy for Fe in liquid Cu (10 kJ/mol) and the difference in surface energy per molar area between Fe and FeO (44.9 kJ/mol). At the Cu/TC4 joining side, the wetting activation energy (23.6 kJ/mol) corresponded to the diffusion activation energy for Ti in liquid Cu (21 kJ/mol). The diffusion of Ti and Fe in molten Cu caused variations in capillary force, which were attributed to changes in the micro-grooves.

Co-sputtered Cu(Ti) thin alloy film for formation of Cu diffusion and chip-level bonding

Co-sputtered Cu(Ti) films on SiO2 substrates exhibit the phase separation of Cu and Ti after annealing at 400 °C. In this study, the diffusion behavior and phase separation were investigated using X-ray photoelectron spectroscopy (XPS), grazing angle incident X-ray diffraction (GIXRD), and transmission electron microscopy (TEM). The GIXRD pattern revealed that the Cu peak replaced the Cu2O peak after annealing. The formation Gibbs free energy of TiO2 (−812 kJ) was lower than that of Cu2O (−109 kJ). The calculated diffusivity of Ti in Cu was one order of magnitude smaller than that of Cu in Cu. Thus, Ti was the dominant diffusing species that accumulated near SiO2, whereas Cu atoms were segregated near the surface. A few Cu islands were initially formed, and these Cu islands grew and formed continuous Cu layers after long-term annealing at 400 °C. The Cu(Ti) films were bonded face-to-face through thermo-compression. The nearly oxide-free Cu yields strong Cu bonding and a void-free interface.

Effect of intermetallic compounds on the thermal conductivity of Ti-Cu composites

Ti films were deposited by magnetron sputtering on polycrystalline Cu substrates. The samples were annealed at different temperatures and characterized by x-ray diffraction for phase identification, scanning electron microscopy, and energy dispersive spectrometry for microstructure and composition and transient thermoreflectance for thermal conductivity and interface thermal conductance. The results showed that the diffused layer of Ti in Cu contained intermetallic compounds and solid solution of Ti in Cu. The thermal conductivity of the diffused layer is reduced, and the thickness increased for higher annealing temperature. The interface thermal conductance also decreased for higher temperature of annealing. A stable Cu4Ti phase was formed after annealing at 725 °C with thermal conductivity of 10 W m−1 K−1. The interface thermal conductance between the intermetallic compound and the solid solution of Ti in Cu also was reduced to 30 MW m−2 K−1. The effective thermal resistance of the diffused layer and the interface was found to increase for higher annealing temperature.

Diffusion characteristics in the Cu–Ti system

Abstract The formation and growth of intermetallic compounds by diffusion reaction of Cu and Ti were investigated in the temperature range 720–860°C using bulk diffusion couples. Only four, out of the seven stable intermediate compounds of the Cu–Ti system, were formed in the diffusion reaction zone in the sequence CuTi, Cu4Ti, Cu4Ti3 and CuTi2. The activation energies required for the growth of these compounds were determined. The diffusion characteristics of Cu4Ti, CuTi and Cu4Ti3 and Cu(Ti) solid solution were evaluated. The activation energies for diffusion in these compounds were 192.2, 187.7 and 209.2 kJ mol−1 respectively, while in Cu(Ti), the activation energy increased linearly from 201.0 kJ mol−1 to 247.5 kJ mol−1 with increasing concentration of Ti, in the range 0.5–4.0 at.%. The impurity diffusion coefficient of Ti in Cu and its temperature dependence were also estimated. A correlation between the impurity diffusion parameters for several elements in Cu matrix has been established.

Comparative analysis of thermal crystallization in Cu50Ti50 and Cu50Zr50 metallic glasses

Abstract The present paper reports a comparative study of crystallization kinetics in two important metallic glasses Cu 50 Ti 50 and Cu 50 Zr 50 in terms of kinetic parameters of crystallization (activation energy of crystallization E c , crystallization temperature T c and rate of crystallization K ) and thermodynamic parameter of crystallization (enthalpy of crystallization H c and the specific heat C p of crystallization). The results are explained in terms of physical properties of additive elements M=Ti and Zr in Cu 50 M 50 system.

Purification of Cu by hydrogen plasma-arc zone melting and characterization of trace impurities by secondary ion mass spectrometry

Purification of 4N (99.99%) and 6N (99.9999%) purity Cu rods by hydrogen plasma-arc zone melting was carried out. Weight loss in the 4N and 6N Cu rods as a function of number of zone refined passes revealed a higher rate of impurity removal by vaporization in 4N Cu when compared to 6N Cu. Purification effect was studied by analyzing major impurities like Mg, Si, Ca, Ti, Cr, Ni and Fe by O 2 + ions and C, O, As, Cl, P and S by Cs + ion sources using secondary ion mass spectrometry. A remarkable decrease of Si, Ti and Fe impurity concentrations in Cu at x/ L = 0.03 after 10 zone passes was observed, but no similar purification effect along the remaining length of the zone refined copper rod was observed. Mg, Se and Ca in the Cu rods were reduced faster by a high evaporation effect due to P i/ P Cu > 10 2. On the other hand, removal of O, C, S and Se was expectedly dominated by vaporization in the form of H 2O, CH 4, H 2S, and H 2Se through thermodynamically favored reactions. The overall segregation rate of the individual impurity elements was decreased with an increase in the purity from 4N to 6N of Cu rods. SIMS analysis of trace impurities was successfully carried out on HPZM Cu for quantitative estimation.

INAA and ICP-MSHS: Metal pollutants in fish tissues Nile tilapia (Oreochromic niloticus) in Pampulha Lake, Belo Horizonte city, Minas Gerais State, Brazil

Pampulha Lake, Minas Gerais, Brazil, is being polluted via its tributaries, Sarandi and Ressaca. Instrumental neutron activation analysis and inductively coupled plasma mass spectrometry high resolution were applied to determine Al, As, B, Ba, Co, Cr, Cs, Cu, Fe, K, Mg, Mn, Mo, Na, P, Pb, Rb, Zn and Ti in Nile tilapia fish, Oreochromis niloticus. The organs analyzed were: intestine, spleen, heart, testicle, kidney, liver, gills and muscle. The results demonstrated relatively high concentrations of Al, Co, Cu, Fe, P and Ti in gills, Al and Cu in liver, Al in intestine and Fe in muscle and spleen.

Effect of Titanium on Glass-forming Ability of Cu-Zr-Al Alloys

The effect of partial substitution of Ti for Zr on the glass-forming ability was studied in Cu 50 Zr 45-x Ti x Al 5 (x = 0, 2.5, 5, 10) alloys by using thermal analysis and X-ray diffractometry. The glass transition temperature, Tg, of Cu 50 Zr 45-x Ti x Al 5 alloys decreased from 707 K at x = 0 to 700K at x = 2.5, and keeps almost constant with further increase of x. On the other hand, the crystallization temperature, T x , decreased gradually from 767 K at x = 0 to 741 K at x = 10. The partial substitution of Zr by Ti in Cu 50 Zr 45 Al 5 alloy promotes the glass formation. The maximum diameter for glass formation by injection casting increased from 3 mm for Cu 50 Zr 45 Al 5 alloy to 4 mm for Cu 50 Zr 42.5 Ti 2.5 Al 5 alloy.

Cu-Based Bulk Glassy Alloys with Good Mechanical Properties in Cu-Zr-Hf-Ti System

High-strength Cu-based bulk glassy alloys were synthesized in Cu-Zr-Ti and Cu-Hf-Ti ternary and Cu-Zr-Hf-Ti quaternary systems by copper mold casting. The critical diameter was 4mm for the Cu 60 Zr 30 Ti 10 and Cu 60 Hf 25 Ti 15 ternary alloys and the Cu 60 Zr 20 Hf 10 Ti 10 and Cu 60 Zr 10 Hf 15 Ti 15 quaternary alloys. As the substitution amount of Zr or Hf by Ti in Cu 60 Zr 40 and Cu 60 Hf 40 alloys increases, the glass transition temperature (Tg), crystallization temperature (T x ) and temperature interval of supercooled liquid region ΔT x (= T x - T g ) decrease, while the liquidus temperature (T l ) has a minimum of 1127 K around 20%Ti, resulting in a maximum T g /T l of 0.63 in the vicinity of 20%Ti. The high glass-forming ability was obtained at the compositions with high T g /T l . The bulk glassy alloys exhibit high fracture strength of 2040-2190 MPa and plastic elongations of 0.3 to 1.9%. The finding of the Cu-based bulk glassy alloys with high T g /T l above 0.60, high fracture strength above 2000 MPa and distinct plastic elongation is encouraging for the subsequent development as a new type of bulk glassy alloys which can be used for structural materials.

Thermodynamics of Ti in Cu–Ti alloy investigated by the EMF method

Abstract The thermodynamics of Ti in Cu–Ti alloy at 1423 K was determined by means of an oxygen sensor employing ZrO 2 (2.14wt%MgO) as the solid electrolyte. Ti 2 O was the equilibrium phase in the interfacial reaction layer formed by the reaction of Ti with Al 2 O 3 . Activities of titanium and copper relative to pure solid state were investigated, and both Cu and Ti in the system showed negative deviation from Raoult’s law. The increment of Ti concentration increased the activity coefficient of Ti and reduced the activity coefficient of copper. The activity coefficient of titanium in infinite dilution copper, γ Ti 0 , self-interaction coefficient e Ti Ti , and the standard Gibbs free energy of solution of Ti in copper relative to 1wt% Ti, Δ G 0 (Ti in Cu melt) at 1423 K were measured in the present study being γ Ti 0 = 0.200, e Ti Ti =4.828 and Δ G 0 (Ti in Cu melt) =−70.179 kJ/mol respectively. The thermodynamic functions of mixing and excess were determined at 1423 K, respectively, Δ G Cu−Ti X =Δ H Cu−Ti M =−19.17 X Ti +33.07 X Ti 2 (kJ/mol) ( X Ti ≤0.0325), and Δ G Cu−Ti M =−0.093−78.67 X Ti +344.9 X Ti 2 (kJ/mol) (X Ti ≤0.0325). The limiting partial enthalpy of solution of supercooled liquid Ti in copper at 1373 K was found to be −11.97 kJ/mol according to regular solution method.

Thermodynamics of nitrogen in BaO-TiOx melts

Using a gas-slag-metal equilibration technique, nitrogen contents in BaO-TiO^ slags and nitrogen and titanium contents in liquid Cu were measured at 1823, 1873, and 1923 K under controlled partial pressures of oxygen(@#@ PO 2 = 10-11.5 ≈ 10-13.7 atm) and nitrogen(@#@ PN 2 = 0.9 atm). The nitride capacity, C(N) [=(mass pct N) · PO2/3/4, (mass pct Ti3+)/(mass pct Ti4+) ratio, and solubility of TiN in BaO-TiO2-TiO1.5 slags were obtained as a function of slag com-position(@#@ XBaO = 0.20 = 0.43) and temperature. Activity coefficients of TiN were estimated, using the values for activity coefficients of Ti in liquid Cu which were calculated from the results of a TiN saturation experiment. Free energy of dissolution of nitrogen into liquid Cu was derived as °GGN o = 32,400 + 46.17 ± 1400 (J/g · atom).

Nanocrystalline phase formation and extension of solid solubility by mechanical alloying in Ti-based systems

The formation of nanocrystalline phases in TiNi, TiCu systems has been studied by mechanical alloying. In all the above systems, mechanical alloying of the pure metal powder mixture (initial powder particle size - 45 μm) has resulted in the formation of particles of about 20 nm size. The particle size after mechanical alloying has been determined from the X-ray peak broadening using Scherrer's formula (L = 0.9 λ/ β cos θ) after separating out the contribution from lattice strains. Large extensions of solid solubility when compared to the equilibrium solid solubility have been observed after mechanical alloying, which has been attributed to the formation of nanocrystals. The X-ray peak shifts after mechanical alloying have indicated a solid solubility of about 18 at.% and 10 at% Ti in Ni and Cu respectively in the case of binary TiNi and TiCu systems which are far in excess of the equilibrium solid solubility for the respective systems.

Thermodynamics of nitrogen in CaO‐TiO2‐TiO1.5 slags

The nitride capacities in CaO‐TiO2‐TiO1.5 slags, and nitrogen distribution ratio between these slags and liquid Cu (LN = (mass‐% N)/[mass‐% N]) were measured by a gas‐slag‐metal equilibration technique, using a Mo crucible in the temperature range of 1823 to 1923 K under controlled partial pressures of oxygen and nitrogen . The values for , (mass‐% Ti3+)/(mass‐% Ti4+) ratio, and solubility of TiN in CaO‐TiO2‐TiO1.5 slags were obtained as a function of slag composition (XCaO = 0.24 ∼ 0.39) and temperature. Activity coefficients of TiN were evaluated from the values for activity coefficients of Ti in liquid Cu which were calculated from the results of TiN saturation experiments.

Thermochemistry of liquid alloys of transition metals II. (Copper + titanium) at 1372 K

The enthalpies of mixing of solid titanium with liquid copper have been measured at 1372 K by high-temperature reaction calorimetry. The enthalpies of mixing, referred to the pure liquid components, have been calculated using literature values for the enthalpy of fusion and for the heat capacities of solid and liquid titanium. In this way the limiting partial enthalpy of solution of undercooled liquid Ti in liquid Cu at 1372 K is found to be − 7.65 kJ mol −1. We have found a well-defined minimum in the enthalpy interaction parameter, ΔH mix 1+l x(1 - x) , near x(Ti) = 0.5, which indicates some tendency toward chemical short-range order. The results have been compared with estimates derived from phase-diagram information, and from Miedema's theory. The agreement with the phase-diagram estimates is very good. However, our results differ significantly from the Miedema predictions.

A metastable phase TiCu3(m)

A metastable phase TiCu3(m) has been prepared by rapid quenching from the melt (splat cooling). TiCu3(m) is orthorhombic, D0a type, with a0 = 5.450, b0 = 4.426, and c0 = 4.307 Å. Although TiCu3(m) is isotypic with a nonexistent equilibrium phase `TiCu3' reported in the literature, its structure is distinctly different from that of `TiCu3'; instead, TiCu3(m) is closely related to ZrAu3. A large metastable solid solubility of Ti in Cu was found.

Conduction-Electron Spin Relaxation by Transition-Element Impurities in Copper

Gossard et al. have recently measured the conduction-electron spin-flip cross sections σsf of the transition elements Ti, Mn, and Ni in Cu. We give here an interpretation of these measurements based on the Anderson-Friedel theory of localized virtual states. σsf is found to be proportional to the square of the d density of states at the Fermi level and to the square of the spin-orbit coupling which is modified by an orbital enhancement factor. Thus as one moves across the transition series, the variation of σsf should show a qualitative resemblance to that of the residual resistivity ρ, and in particular show a minimum at Mn, in agreement with experiment. The precise variation of σsf is more pronounced and more asymmetric with respect to Mn than that of ρ. Inclusion of the crystal-field splitting affects greatly the calculated value of σsf for Ni and it is concluded that the splitting for Ni must be very small or inverted. Assuming U = 3 eV and J = 0.5 eV, it is found that the values of the virtual level half-width Δ needed to make the calculated σsf agree with experiment are Δ = 1.0 eV for Ti and Δ = 0.3 eV for Ni.

Nuclear-Magnetic-Resonance and X-Ray Study of Solute Loss by Internal Oxidation in Comminuted and Vaccum-Annealed Cu-Mn Alloys

It is shown that Cu-Mn alloys lose part of their solute Mn during comminution and vacuum annealing. X-ray measurements indicate that the solute loss occurs by the mechanism of internal oxidation, the dominant oxide formed being MnO (manganosite). NMR and x-ray measurements have been correlated in terms of loss of solute Mn from the Cu lattice. The results indicate that physical measurements on both annealed and unannealed samples of powdered Cu-Mn alloys can lead to errors in interpretation, if measured parameters are correlated with solute concentrations obtained directly from chemical analysis. Similar effects were observed with solutes of Ti, Fe, and Al in Cu.