Microstructural and thermochemical properties of Al/AlN/CuAl2 composite prepared by a combination of combustion synthesis and spark plasma sintering

A combination of combustion synthesis (CS) and spark plasma sintering (SPS) technology was employed in the fabrication of Al/AlN/CuAl₂ dense composites. Al/AlN/CuAl₂ composite powders in which a portion of the AlN was present in macro- and nanofiber forms were prepared by combustion of Al–Cu–5 wt.% (C₂F₄)_n, under a nitrogen atmosphere. The resulting composite powders were then subjected to consolidation by SPS at a dwell temperature level of 1500 °C, mechanical pressure of 60 MPa, and a non-isothermal heating time of 10 min. It is found that the actual thermal conductivity of Al/AlN/CuAl₂ composites fabricated with 5 wt.% (C₂F₄)_n is much higher than that of materials prepared in the absence (C₂F₄)_n. Maximum thermal conductivity (320 W/m K) was recorded for the samples prepared from an 0.8Al–0.2Cu–5 wt.% (C₂F₄)_n mixture. The influence of (C₂F₄)_n on the growth mechanism of AlN fibers and thermal conductivity of composite samples is discussed in light of the experimental data.     

(C2N2H10)[FexV1−x(HPO3)F3] (x = 0.44, 0.72): Two new organically templated phosphites: Solvothermal synthesis and structural,thermal, spectroscopic and magnetic studies

(C₂N₂H₁₀)[Fe_xV_1−x(HPO₃)F₃] (x = 0.44, 0.72) have been synthesized using mild solvothermal conditions under autogenous pressure and the ethylenediamine molecule as templating agent. The crystal structures have been determined from X-ray single-crystal diffraction data. The compounds crystallize in the orthorhombic P2₁2₁2₁ space group with Z = 4 and unit-cell parameters a = 12.8494(9), b = 9.5430(6), c = 6.4372(5) Å, and a = 12.8578(1), b = 9.5342(1), c = 6.4370(7) Å for (C₂N₂H₁₀)[Fe_0.44V_0.56(HPO₃)F₃] and (C₂N₂H₁₀)[Fe_0.72V_0.28(HPO₃)F₃], (1) and (2), respectively. These isostructural compounds exhibit a monodimensional crystal structure formed by pillared double anionic chains with the formula [M(HPO₃)F₃]²⁻, extended along the [0 0 1] direction. These doubled ionic chains are the result of the linking of two simple chains in which there are alternating octahedral [MO₃F₃] and tetrahedral groups [HPO₃]. The ethylendiammonium cations are placed in the space delimited by three different chains. The metallic ions are interconnected by the pseudo-pyramidal (HPO₃)²⁻ phosphite oxoanions, adopting a slightly distorted octahedral geometry. The IR spectra show bands corresponding to the phosphite oxoanion and the ethylendiamonium cation at 2400 and 1600 cm⁻¹, respectively. The thermogravimetric analyses show that these phases are stable up to ca. 280 °C, at higher temperatures, the decomposition of the crystal structure begins by calcination of the organic cation and the elimination of the fluoride anions. The diffuse reflectance spectra show bands of the V³⁺ ion (d²) in octahedral symmetry. The values of the Dq (1540, 1540 cm⁻¹), and Racah parameters, B (560, 535 cm⁻¹) and C (3055, 3140 cm⁻¹) for (1) and (2), respectively, correspond with those usually found for octahedrically coordinated V(III) compounds. Magnetic measurements, performed on a powered sample from 5.0 to 300 K at 1000 G, in the ZFC and FC modes, indicate the existence of antiferromagnetic interactions.     

Microstructure and transport properties of Bi1.6Pb0.5Sr2−xLuxCa1.1Cu2.1O8+δ superconductor

The microstructure and electrical properties of the rare-earth Lu doped (Bi, Pb)-2212 superconductor have been investigated. The Lu concentration is varied from x = 0.000 to 0.150 in a general stoichiometry of Bi_1.6Pb_0.5Sr_2?xLu_xCa_1.1Cu_2.1O_8+δ. The X-ray diffractometer and energy dispersive X-ray spectroscopy analyses show that Lu atoms are successfully substituted into the (Bi, Pb)-2212 system and they induce significant changes in the microstructure, hole concentration, critical temperature, self- and in-field critical current density of the system. The flux pinning force (F_P) calculated from the field dependant J_C values shows that the irreversibility lines (IL) of the Lu substituted (Bi, Pb)-2212 shift towards higher fields to different extents depending on the Lu stoichiometry. The samples with x = 0.100 show a maximum F_P of 1395 ± 1 × 10³ N m^?3 as against 30 ± 1 × 10³ N m^?3 for the pure sample. The changes in hole concentration followed by very high enhancement of critical temperature (T_C), self-field J_C, J_C(B) characteristics and F_P due to Lu substitution are of great scientific and technological significance and the results are explained on the basis of microstructural variation with respect to Lu stoichiometry, hole optimization and formation of point defects due to the doping of Lu atoms in Bi_1.6Pb_0.5Sr_2?xLu_xCa_1.1Cu_2.1O_8+δ system.     

Importance of H2 gas for growth of hot-wire CVD nanocrystalline 3C-SiC from SiH4/CH4/H2

Silicon carbide (SiC) thin films were prepared by hot-wire chemical vapor deposition from SiH₄/CH₄/H₂ and the influence of H₂ gas flow rate (F(H₂)) on the film properties was investigated. The SiH₄ gas flow rate was 1 sccm. At the CH₄ gas flow rate (F(CH₄)) of 1 sccm, nanocrystalline cubic SiC (nc-3C-SiC) grew even without H₂. On the other hand, at F(CH₄) = 2 sccm, amorphous SiC grew without H₂ and nc-3C-SiC grew above F(H₂) = 50 sccm. As F(H₂) was increased, the crystallinity improved both at F(CH₄) = 1 and 2 sccm. However, the mean crystallite size decreased at F(CH₄) = 1 sccm and increased at F(CH₄) = 2 sccm. We discuss growth mechanisms of nc-3C-SiC.     

Rapid synthesis of gold nanostructures by a microwave–polyol method with the assistance of CnTAB (n = 10, 12, 14, 16) or C16PC

Gold nanostructures have been synthesized by a microwave(MW)–polyol method with the assistance of such cationic surfactants as alkyltrimethyl ammonium bromide (C_nTAB: n = 10–16, even numbers) or cetylpryridinium chloride (C₁₆PC). Although major products were spherical aggregates for C_nTAB (n = 10, 12, 14), triangular, pentagonal, and hexagonal nanoplates were preferentially synthesized using C₁₆TAB. Spherical spike-ball structures were prepared through C₁₆PC. These results indicated that the morphology of gold nanostructures prepared by the MW–polyol method depends both on the chain length of hydrophobic alkyl group and on the hydrophilic head group.     

AGET ATRP of acrylonitrile with ionic liquids as reaction medium without any additional ligand

Atom transfer radical polymerization using activators generated by electron transfer (AGET ATRP) of acrylonitrile (AN) was carried out for the first time in 1-methylimidazolium acetate ([mim][AT]), 1-methylimidazolium propionate([mim][PT]), and 1-methylimidazolium butyrate ([mim][BT]), respectively. The polymerization was approached by using ascorbic acid (VC) as a reducing agent, ethyl 2-bromoisobutyrate (EBiB) as initiator, only FeBr₃ as catalyst without any additional ligand. Kinetic studies showed that both AGET ATRP of AN in the absence of oxygen and in the presence of air proceeded in a well-controlled manner. Under the same conditions, the polymerization in the presence of air provided rather slower reaction rate and showed better control of molecular weight and its distribution than in the absence of oxygen. The sequence of the apparent polymerization rate constants of AGET ATRP of AN in three ionic liquids was k_app([mim][AT]) > k_app([mim][PT]) > k_app([mim][BT]). The living nature of the polymerization was confirmed by chain end analysis and block copolymerization of methyl methacrylate with polyacrylonitrile as macroinitiator. All the three ionic liquids and FeBr₃ could be recycled and reused and had no effect on the living nature of polymerization.     

Release of interfacial thermal stress and accompanying improvement of interfacial adhesion in carbon fiber reinforced epoxy resin composites: Induced by diblock copolymers

In this work, diblock copolymer Hydroxyl-Terminated poly (n-butylacrylate)-b-poly (glycidyl methacrylate) (OH-PnBA-b-PGMA) was synthesized by atom transfer radical polymerization (ATRP) and was then introduced into the interface between carbon fiber and epoxy resin. Micro-Raman spectroscopy and microbond test were employed to study the influence of grafted polymers on the interfacial properties. From the Micro-Raman spectroscopy results, the interfacial thermal stress in carbon fiber/epoxy resin micro-composite decreases from 546.9 MPa to 451.9 MPa due to the grafting of OH-PnBA₁₈₀-b-PGMA₇₀ on the carbon fiber. Meanwhile, the interfacial shear strength (IFSS) value increases rapidly from 29.8 MPa to 52.3 MPa, measured by microbond test. Therefore, it can be concluded that such a diblock copolymer can effectively both release the thermal stress and improve the interfacial adhesion. Moreover, it proves that the length of PnBA block has great influence on the interfacial properties of carbon fiber/epoxy composite.     

Oxygen plasma functionalization of parylene C coating for implants surface: Nanotopography and active sites for drug anchoring

The effect of oxygen plasma treatment (t = 0.1–60 min, p_O2 = 0.2 mbar, P = 50 W) of parylene C implant surface coating was investigated in order to check its influence on morphology (SEM, AFM observations), chemical composition (XPS analysis), hydrophilicity (contact angle measurements) and biocompatibility (MG-63 cell line and Staphylococcus aureus 24167 DSM adhesion screening). The modification procedure leads to oxygen insertion (up to 20 at.%) into the polymer matrix and together with surface topography changes has a dramatic impact on wettability (change of contact angle from θ = 78 ± 2 to θ = 33 ± 1.9 for unmodified and 60 min treated sample, respectively). As a result, the hydrophilic surface of modified parylene C promotes MG-63 cells growth and at the same time does not influence S. aureus adhesion. The obtained results clearly show that the plasma treatment of parylene C surface provides suitable polar groups (C = O, C–O, O–C = O, C–O–O and O–C(O)–O) for further development of the coating functionality.     

Synthesis,mechanical and physical properties of bulk Zr2Al4C5 ceramic

Bulk Zr₂Al₄C₅ ceramics was synthesized by an in situ reactive hot-pressing process using ZrC, Al and carbon black as staring materials. The reaction path of synthesis was discussed based on differential thermal analysis, Raman spectra and X-ray diffraction results. Compared with the reported Zr₂Al₃C₄, Zr₂Al₄C₅ has a relatively high hardness (Vickers hardness of 12.2 GPa), superior strength (flexural strength of 420 MPa) and lower electrical resistivity (1.05 μΩ m). In addition, the room-temperature thermal conductivity value, 14.6 W (m K)^?1 for Zr₂Al₄C₅, was smaller than the value for Zr₂A₃C₄ ceramics (15.5 W (m K)^?1), and the heat capacity of Zr₂Al₄C₅ is much higher than that of Zr₂A₃C₄ in the overall temperature range. The results here indicated that Zr₂Al₄C₅ is a potential high-temperature structural ceramic.     

Visible to infrared energy conversion in Pr3+–Yb3+ co-doped fluoroindate glasses

Processes involving visible to infrared energy conversion are presented for Pr³⁺–Yb³⁺ co-doped fluoroindate glasses. The emission in the visible and infrared regions, the luminescence decay time of the Pr³⁺:³P₀ → ³H₄ (482 nm), Pr³⁺:¹D₂ → ³H₆ (800 nm), Yb³⁺:²F_5/2 → ²F_7/2 (1044 nm) transitions and the photoluminescence excitation spectra were measured in Pr³⁺ samples and in Pr³⁺–Yb³⁺ samples as a function of the Yb³⁺ concentration. In addition, energy transfer efficiencies were estimated from Pr³⁺:³P₀ and Pr³⁺:¹D₂ levels to Yb³⁺:²F_7/2 level. Down-Conversion (DC) emission is observed due to a combination of two different processes: 1-a one-step cross relaxation (Pr³⁺:³P₀ → ¹G₄; Yb³⁺:²F_7/2 → ²F_5/2) resulting in one photon emitted by Pr³⁺ (¹G₄ → ³H₅) and one photon emitted by Yb³⁺ (²F_7/2 → ²F_5/2); 2-a resonant two-step first order energy transfer, where the first part of energy is transferred to Yb³⁺ neighbor through cross relaxation (Pr³⁺:³P₀ → ¹G₄; Yb³⁺:²F_7/2 → ²F_5/2) followed by a second energy transfer step (Pr³⁺:¹G₄ → ³H₄; Yb³⁺:²F_7/2 → ²F_5/2). A third process leading to one IR photon emission to each visible photon absorbed involves cross relaxation energy transfer (Pr³⁺:¹D₂ → ³F₄; Yb³⁺:²F_7/2 → ²F_5/2).     

Effect of processing parameters on structural,morphological and optical Y2O3:Yb3+/Ho3+ powders characteristics

Rod-like and flake-like up-converting Y₂O₃:Yb³⁺/Ho³⁺ particles which are composed of nanoparticles with size less than 100 nm, are prepared by a simple hydrothermal processing at 473 K (3 h) followed by additional thermal treatment at 1373 K (3 and 12 h). The effect of precursor pH value on the formation of Y₂O₃:Yb³⁺/Ho³⁺ is followed through X-ray powder diffractometry (XRPD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Structural refinement confirms formation of the cubic bixbyte structure (S.G. Ia-3) with the non-uniform accommodation of dopants at C₂ and S₆ cationic sites. Under 978 nm laser excitation, strong green (530–570 nm) up-conversion is observed in all samples. The emission shows a decrease in intensity with an increase in external temperature, indicating FIR (fluorescence intensity ratio) based temperature sensing behavior of 0.52% for the ⁵F₄ → ⁵I₈/⁵S₂ → ⁵I₈ transitions.     

Robust Flower‐Like TiO2@Cotton Fabrics with Special Wettability for Effective Self‐Cleaning and Versatile Oil/Water Separation

Inspired by the hierarchical structure of the mastoid on the micrometer and nanometer scale and the waxy crystals of the mastoid on natural lotus surfaces, a facile one‐step hydrothermal strategy is developed to coat flower‐like hierarchical TiO₂ micro/nanoparticles onto cotton fabric substrates (TiO₂@Cotton). Furthermore, robust superhydrophobic TiO₂@Cotton surfaces are constructed by the combination of hierarchical structure creation and low surface energy material modification, which allows versatility for self‐cleaning, laundering durability, and oil/water separation. Compared with hydrophobic cotton fabric, the TiO₂@Cotton exhibits a superior antiwetting and self‐cleaning property with a contact angle (CA) lager than 160° and a sliding angle lower than 5°. The superhydrophobic TiO₂@Cotton shows excellent laundering durability against mechanical abrasion without an apparent reduction of the water contact angle. Moreover, the micro/nanoscale hierarchical structured cotton fabrics with special wettability are demonstrated to selectively collect oil from oil/water mixtures efficiently under various conditions (e.g., floating oil layer or underwater oil droplet or even oil/water mixtures). In addition, it is expected that this facile strategy can be widely used to construct multifunctional fabrics with excellent self‐cleaning, laundering durability, and oil/water separation. The work would also be helpful to design and develop new underwater superoleophobic/superoleophilic materials and microfluidic management devices.     

Fluorescence properties and relaxation processes of Tb3+ ions in ZnCl2-based glasses

60ZnCl₂–20KCl–20BaCl₂–xTbCl₃ glasses (x = 0.10, 0.25, 0.50, 0.75, 1.00, and 1.25) were prepared by melt-quenching method, and Tb³⁺ fluorescence properties were investigated under 355 nm excitation. Regardless of x values, the electrons that were relaxed from the ⁵D₃ to ⁵D₄ level of Tb³⁺ ions by the multiphonon relaxation, were repressed to 28% of all the excited electrons because the ZnCl₂-based glass had much lower phonon energy than oxide glasses. For 0 < x ≤ 0.34, the cross relaxation, (⁵D₃ → ⁵D₄) → (⁷F₀ ← ⁷F₆), was repressed, and consequently 72% and 28% of all the excited electrons were radiatively relaxed by the ⁵D₃ → ⁷F_J (J = 6, 5, 4, 3, and 2) and ⁵D₄ → ⁷F_J (J = 6, 5, 4, and 3) transitions, respectively. The lifetimes of the ⁵D₃ and ⁵D₄ initial levels were obtained to be 1.1 and 2.1 ms, respectively.     

Spectroscopic investigations on Eu3+ ions in Li–K–Zn fluorotellurite glasses

Eu³⁺ ions incorporated Li–K–Zn fluorotellurite glasses, (70 − x)TeO₂ + 10Li₂O + 10K₂O + 10ZnF₂ + xEu₂O₃, (0 ⩽ x ⩽ 2 mol%) were prepared via melt quenching technique. Optical absorption from ⁷F₀ and ⁷F₁ levels of the Eu³⁺-doped glass has been studied to examine the covalent bonding characteristics, energy band gap and Judd–Ofelt intensity parameters. The emission spectra (⁵D₀ → ⁷F_0,1,2,3,4) of the glasses were used to estimate the luminescence enhancement, asymmetric environment in the vicinity of Eu³⁺ ions, stimulated emission cross section and branching ratios. The phonon side band mechanism of ⁵D₂ level of the Eu³⁺ ions in the prepared glass was examined by considering the excitation and Raman spectra. The radiative lifetime calculated using Judd–Ofelt parameters was compared with the experimental lifetime to estimate the quantum efficiency of ⁵D₀ level of Eu³⁺ ions in Li–K–Zn fluorotellurite glass.     

Photoluminescence properties of Y3Al5O12:Eu nanocrystallites prepared by co-precipitation method using a mixed precipitator of NH4HCO3 and NH3·H2O

Europium-doped yttrium aluminum garnet (Y₃Al₅O₁₂:Eu, YAG:Eu) nanocrystallites were prepared by calcining the precursors obtained via a co-precipitation method using a mixed solution of NH₄HCO₃ and NH₃·H₂O as the precipitator. The results of XRD, FTIR and thermal analysis showed that phase-pure YAG:Eu without any other phases was obtained at 900 °C. TEM results indicated that the particle sizes are 50–100 nm. YAG:Eu nanocrystallites showed four emission bands ascribed to ⁵D₀ → ⁷F₁ transition (592 and 597 nm) and ⁵D₀ → ⁷F₂ transition (611 and 633 nm) of Eu³⁺, respectively. The intensity of the magnetic dipole transition (⁵D₀ → ⁷F₁) is stronger than that of the electric dipole transition (⁵D₀ → ⁷F₂). The influence of the precipitators with different molar ratios of NH₄HCO₃ to NH₃·H₂O on the thermal properties of the as-prepared precursors and luminescent properties of the resulting YAG:Eu nanocrystallites was also investigated.     

Effect of electron irradiation on characteristics of Mo Schottky barriers on epitaxial silicon

The results of studies on influence of 6 MeV electron irradiation on avalanche breakdown voltage (U_b) and on forward voltage (U_F) at different values of direct current (I_F) for the Mo Schottky diodes on epitaxial silicon of n-type conductivity are presented. It was found out that the avalanche breakdown voltage of the diodes is very sensitive to electron irradiation. A decrease in U_b was observed after electron irradiation with a fluence as low as 1 × 10¹¹ cm^?2. An increase in electron irradiation fluence from 1 × 10¹¹ cm^?2 to 5 × 10¹⁴ cm^?2 resulted in 30% decrease in U_b, however, further increase in electron irradiation fluence from 5 × 10¹⁴ cm^?2 to 3 × 10¹⁶ cm^?2 led to some increase in the avalanche breakdown voltage. Monotonic increases in U_F values at different I_F with the increase in electron irradiation fluence were observed starting from a fluence of 5 × 10¹⁴ cm^?2. Radiation-induced changes in U_b were unstable at room temperature and a significant recovery of U_b occurred after maintaining the irradiated diodes at room temperature for 30 days. Annealing at 120 °C for 20 min resulted in the almost complete recovery of U_b. Radiation-induced changes in U_F values were stable up to 300 °C. Mechanisms of the observed radiation-induced changes in the U_b and U_F values and defects responsible for the changes are discussed.     

Luminescence properties of Yb:Er:KY3F10 nanophosphor and thermal treatment effects

In this work, we present the spectroscopic properties of KY₃F₁₀ nanocrystals activated with erbium and codoped with ytterbium ions. The most important processes that lead to the erbium upconversion of green and red emissions of Er³⁺ were identified. A time-resolved luminescence spectroscopy technique was employed to measure the luminescence decays of ⁴S_3/2 and ⁴F_9/2 excited levels of Er³⁺ and to determine the upconversion processes and the luminescence efficiencies of erbium in the visible. Analysis of the luminescence kinetics in Yb:Er:KY₃F₁₀ shows a rapid upconversion (Up₁) for the green emission with a time constant of 0.31 μs after pulsed laser excitation at 972 nm for as synthesized nanocrystals, which is faster than the time constant measured for the bulk crystal (23 μs). In addition, it is observed a second upconversion process (non-resonant) (Up₂) responsible for the red emission (Er³⁺), which competes with Up₁ process. However, the luminescence efficiency of the green emission (⁴S_3/2) is observed to be very low (1.6%) for the as synthesized nanocrystal (25 °C). Nevertheless, it increases with the nanopowder heat treatment reaching an efficiency of 99% (T = 550 °C) relative to the bulk crystal. Similar luminescence behavior was observed for the ⁴F_9/2 level (Er³⁺) that emits red emission. X-ray diffraction analysis of nanopowder by Rietveld method reveled that the mean crystallite size remains unchanged (8.3–12.3 nm) after thermal treatments with T ∼ 400 °C, while the ⁴S_3/2 luminescence efficiency strongly increases to 20%. The luminescence dynamics indicates that Er³⁺ ions distribution plays a determinant role in the luminescence efficiency of green and red emissions of Er³⁺ besides also the strong influence on the upconversions processes. The observed luminescence effect is caused by the non-uniform Er³⁺ (and Yb³⁺) ions distribution due to the nanocrystal grown, which introduces a concentration gradient that increases towards the nanoparticle surface. This concentration effect produces strong (Er × Er) cross-relaxations depleting the excited states populations of ⁴S_3/2 and ⁴F_9/2 levels and their luminescence efficiencies in KY₃F₁₀ nanocrystals. The concentration gradient is very accentuated in the as synthesized nanocrystal and gradually decreases with the thermal treatments where the dopant ions can migrate through the lattice towards the nanocrystal’s interior to get a more uniform and random distribution, which is reached after heat treatment to T = 550 °C.     

Spectroscopic evaluation of Zn(PO3)2:Dy3+ glass as an active medium for solid state yellow laser

A spectroscopic investigation of zinc phosphate glass activated with 1.0, 5.0 and 10.0 mol% of Dy(PO₃)₃ is performed through absorption and luminescence spectra and decay times to study its potentialities for yellow laser operation upon excitation at 399 nm, which fits to the requirements of GaN LEDs. In the 1.0 mol% Dy(PO₃)₃-doped glass a quantum efficiency of 80 ± 5% was estimated for the dysprosium ⁴F_9/2 level luminescence, the ⁴F_9/2 → ⁶H_13/2 yellow emission shows greater intensity than the ⁴F_9/2 → ⁶H_15/2 blue emission, as well as a very high optical gain, which might make this glass phosphor a promising gain medium for solid state yellow laser pumped by GaN LEDs.     

A TEM Kikuchi pattern study of ECAP AA1200 via routes A,C, BC

Shear plastic deformation in ECAP occurs through the formation, movement and storage of dislocations. The differences which exist between shearing characteristics lead to important implications concerning the optimum processing route. It is known that the effectiveness of cell evolution into an array of high-angle boundaries (HABs) is in the order B_C > C > A, or A > B_C > C, depending on the two-channel-angle intersection of the ECAP die. In route A, large portions of HABs are continuously and progressively generated, while routes C and B_C cause fully redundant deformation at each 2n passes, and each 4n passes, respectively. This study is focused on dislocation generation, storage and recombination during ECAP for routes A, C and B_C. Kikuchi bands identified with TEM were used to quantitatively measure the cell and grain boundary misorientation. ECAP was performed on an AA1200 commercially pure aluminium alloy up to ε = 8.64. A different hierarchy for HAB generation efficiency was found. Thermal stability was studied by annealing the alloy at 0.5, 0.6, 0.7 T_M (where T_M is the alloy melting point) for 2 h after the severe plastic deformation. It appeared that, even if route B_C involves the fastest microstructure grain refining, route C is likely to be the most stable upon reheating.     

Wetting of porous graphite by Cu–Ti alloys at 1373 K

The isotherm wetting of porous graphite substrates by the molten Cu–Ti alloys with 1, 3, 4 and 5 at.% Ti was investigated at 1373 K in a flowing Ar atmosphere using a modified sessile drop method. The wettability increases with increasing Ti content in the alloy and the equilibrium contact angle reaches 6° for the Cu–5 at.% Ti alloy. The improvement of the wettability is due to the formation of a substoichiometric TiC_x reaction layer at the interface. Increasing the Ti content makes the resultant TiC_x phase more substoichiometric and thus significantly promotes the wettability.