Effect Of Ta Content Research Articles

Effect of Ta content on microstructure, martensitic transformation, and shape memory effect of (Ni52.2Ti47.8)100-xTax alloys

This work focuses on the effects of Ta addition on the microstructure, martensitic transformation, mechanical properties and shape memory effect (SME) of (Ni52.2Ti47.8)100-xTax alloys with a fixed Ni/Ti ratio of 1.09. The solubility limit of Ta in (Ni52.2Ti47.8)100-xTax alloys is determined to be within 3–4 at%. Excessive Ta leads to the formation of secondary phases, the majority of which are (Ta,Ti)2Ni phases. The addition of Ta can effectively refine the grains of NiTiTa alloys. Transformation temperatures are elevated remarkably until Ta content reaches 4 at% and then increase slightly at higher Ta contents, which is due to the change of valence electron concentration. The thermal hysteresis is widened by adding Ta and applying a constraint stress. The addition of Ta remarkably improves the ductility while decreases the hardness. By modifying the content of Ta, a considerable SME is achieved with the maximum recovery strain up to 7.0 %.

Effects of Ta content on microstructure and oxidation behavior of AlCoCrFeNiYTax high entropy alloy

Effects of Ta content on microstructure and oxidation behavior of AlCoCrFeNiYTax high entropy alloy

Effect of Ta content on high temperature oxidation and hot corrosion resistance of DZ411 superalloy

Effect of Ta content on high temperature oxidation and hot corrosion resistance of DZ411 superalloy

Constitutive modeling of Ta-rich particle reinforced Zr-based bulk metallic composites in the supercooled liquid region by using evolutionary artificial neural network

In this study, a series of in-situ Ta-rich particle reinforced Zr-based bulk metallic glass composites were successfully fabricated by arc-melting copper-mold spray casting. The effects of Ta content on the room temperature plasticity, compressive strength and thermoplastic formability were studied. (Zr55Cu30Al10Ni5)94Ta6 showed good comprehensive performance, and it was selected to systematically study the deformation behavior in the supercooled liquid region. Different from the strain softening after stress overshoot in bulk metallic glass, the composites showed work hardening in the late stage. Some classical constitutive models cannot accurately describe these phenomena. The back-propagation artificial neural network optimized by particle swarm optimization and genetic algorithm was used to establish the constitutive model. The particle-swarm-optimization back-propagation network with the optimal topology showed high accuracy and good generalization ability. The results predicted with this model were consistent with the experimental data, providing a powerful approach for describing the hot-deformation behavior of these Zr-based bulk metallic glass composites in the supercooled liquid region.

Effect of Ta Content on the Microstructure and Properties of Laser Cladding Ni60A/WC Composite Coatings

Effect of Ta Content on the Microstructure and Properties of Laser Cladding Ni60A/WC Composite Coatings

Toughness mechanism and plastic insensitivity of submicron second phase Ta in a novel Ta–Hf6Ta2O17 composite ceramic

The introduction of metal-second phase can improve the fracture toughness of metal-ceramic composite (MCC) material, but usually degrades the strength and hardness. The pace of exploring the process and materials to both improve the toughness and hardness has never stopped. In this study, a novel Ta–Hf6Ta2O17 composite ceramic is successfully prepared by spark plasma sintering. The effects of Ta content on microstructure and mechanical properties of the as-sintered ceramic are investigated. The fracture toughness of Ta–Hf6Ta2O17 composite ceramic first increases and then decreased slightly with the increase in Ta content, reaching the maximum value of 4.21 ± 0.09 MPa m1/2 at 20 vol% Ta. The improvement of the fracture toughness does not affect the hardness, whose value is stable between 16.74 GPa and 18.43 GPa. Based on the results of Selsing’s model, Raman spectra and TEM, it is confirmed that the toughness mechanism of Ta–Hf6Ta2O17 composite ceramics originates from good inherent interface strength and crack deflection caused by the second phase. The maintenance of hardness comes from the plastic insensitivity of submicron Ta caused by the interfacial tensile stress, which provides a potential mechanism for the design of metal-ceramic composite with excellent strength and toughness.

Effect of Ta Content on Microstructure and Properties of (Ti,W)C-Based Cermets

(Ti,W)C-based cermets are an ideal material for the preparation of high-performance cutting tools due to their excellent mechanical properties, high temperature oxidation resistance, and corrosion resistance. However, their lower toughness limits the application of cutting tools. In order to solve the problem of low toughness faced by the current materials used in tools, in this study, a (Ti,W)C solid solution was used as the hard phase to prepare cermets with high toughness via vacuum sintering. The effects of Ta content on the composition, morphology, and microstructure of the cermets were analyzed through XRD analysis and SEM and EDS characterization methods. The mechanical properties such as hardness, transverse fracture strength, and the fracture toughness of the cermets and corrosion resistance in an HNO3 solution were also investigated. The results show that the microstructure of (Ti,W)C solid solution-based cermets exhibit simpler core-rim (single-rim) and acyclic structures, which weaken the formation and propagation of cracks at the interface. The relative density and grain size of cermets increases and decreases, respectively, with the greater amount of Ta addition, while excessive Ta addition leads to a decrease in the relative density and agglomeration between grains. The cermet with 3 wt.% Ta addition possessed excellent mechanical properties with a Vickers hardness, transverse rupture strength, and fracture toughness of 13 GPa, 1907.4 MPa, and 15.5 MPa m1/2, respectively. The addition of Ta leads to the formation of a Ta-rich protective layer on the surface of the cermet under the corrosion of the acidic solution, and with the increase in the Ta content, the corrosion resistance of the cermet gradually improves.

Effect of Tantalum content on microstructure and mechanical properties of CoCrNiTax medium entropy alloys

CoCrNi medium entropy alloy (MEA) has potential applications in cryogenic environment due to its strength and plasticity enhancement at low temperatures. However, the poor strength at the room temperature limits its widespread application. In this work, the alloying element, Tantalum (Ta), was chosen to strengthen CoCrNi MEA and CoCrNiTax MEAs with different Ta content were designed and prepared. The effect of Ta content on the microstructure and mechanical properties of the corresponding alloys were investigated. It was found that Ta-enriched Laves phase was formed due to the addition of Ta element. The alloy's microstructure experienced from hypoeutectic to eutectic, and then to hypereutectic morphology evolution with increasing Ta addition. CoCrNiTa0.4 alloy was a fully eutectic microstructure with fine lamellar colonies. Its yield strength reached about 2150 MPa, which was greatly improved compared with CoCrNi MEA. In order to understand the strengthen mechanism of CoCrNiTax MEAs, strength contribution of the alloy's individual phase to the lamellar colonies was investigated by the high-throughput nanoindentation mapping technique. It is indicated that Laves phase had very high hardness increasing from ≈16.12 GPa to ≈18.14 GPa, almost 3 times than that of FCC phase (≈6.03 GPa). The strengthening of CoCrNiTax MEAs should be attributed to the production of the hard Laves phase and lamellar colonies.

Microstructure evolution and properties of NiTiCrNbTax refractory high-entropy alloy coatings with variable Ta content

In this work, the novel NiTiCrNbTax (x = 0.1, 0.3, 0.5, 1) refractory high-entropy alloy (RHEA) coatings were successfully synthesized on Ti6Al4V by laser cladding technology. The effect of Ta content on microstructure, thermal stability, micro-hardness and corrosion resistance of RHEA coatings was investigated in detail. The results showed that NiTiCrNbTax RHEA coatings were composed of BCC, NiTi2-Laves and Cr2Nb-Laves phases. With Ta content increasing, the formation of BCC phase was promoted while the precipitate of Cr2Nb-Laves phase was affected. The average micro-hardness values of Ta0.1, Ta0.3, Ta0.5 and Ta1.0 RHEA coatings were calculated as ~922.8 HV0.3, ~985.1 HV0.3, ~851.3 HV0.3 and ~825.4 HV0.3, respectively. The decrease of micro-hardness value might be ascribed to the reduction of hard Laves phase. After annealing at 900 °C for 3 h, the phase compositions of all RHEA coatings remained unchanged but the grains of Cr2Nb-Laves phase were refined obviously. Besides, RHEA coatings exhibited excellent corrosion resistance and the minimum corrosion current density was 1.08 × 10−7 A/cm2. Moreover, the secondary passivation phenomenon emerged in Ta0.5 and Ta1.0 coatings, and the passive film mainly consisted of the oxidation state of Ti, Cr, Nb, Ta and the sub-oxide state of Nb, Ta.

Effect of Ta content on stacking fault energy and microstructure characteristics of (VCoNi)100-XTaX (X = 0, 0.05, 0.5 and 1) medium entropy alloy

Ultra-strong medium entropy alloy (VCoNi) is designed via severe lattice distortion. Simulation calculation suggests the stacking fault energy of VCoNi can be reduced as increasing Ta contents, but keep the deformation twinnability almost unchanged. The experiment result suggests Ta addition can’t remarkably increase the deformation twinning propensity due to the chemical short-range order in VCoNi.

Effects of Ta content on the oxidation and high-temperature tribological behaviors of (Zr, Ta) N coating deposited by double-cathode glow plasma alloy

ZrN-based coatings have attracted significant attention due to their high hardness and outstanding thermal properties. In this research, ZrN, TaN, and (Zr, Ta) N coatings with different Ta content (ZrTaN-1 coating with 30 at.% Ta content and ZrTaN-2 coating with 60 at.% Ta content) were prepared with a double-cathode glow plasma alloy (DGPA). The influence of Ta content on the phase composition, microstructure, mechanical performance, oxidation and tribological behaviour of the coatings was comparatively studied. The results illustrated that the (Zr, Ta) N coatings with different Ta content crystallized in NaCl-type structures. The lattice constants of the (Zr, Ta) N coatings decreased with increasing Ta content because the Ta–N bonds (0.227 nm) were shorter than the Zr–N (0.230 nm) bonds, which confirmed that Zr was successfully substituted with Ta. The oxidation resistivity of the (Zr, Ta) N coatings exhibited minimum mass gain values of 0.55 mg/cm2, 5.12 mg/cm2, and 17.08 mg/cm2 at 650~850 °C with a Ta content of 60 at.%. The addition of Ta effectively reduced the thermal stress of the coatings and avoided cracking and peeling at high temperatures. In addition, high-temperature tribological experiments showed that the wear rate of the (Zr, Ta) N coatings at 500 °C was low and stable and was only 32.9% of that of the ZrN coating under the same conditions. This was attributed to the formation of a dense (Zr, Ta)-rich oxide on the coating surface.

Investigation into Microstructure, Wear Resistance in Air and NaCl Solution of AlCrCoNiFeCTax High-Entropy Alloy Coatings Fabricated by Laser Cladding

AlCrCoNiFeCTax (x = 0, 0.5 and 1.0) high-entropy alloys coatings were synthesized on 45# steel by laser cladding. The microstructural evolution of the coatings with the change in x was analyzed in detail. The effect of Ta content on the wear behaviors of the coatings at different circumstances (in air and 3.5 wt.% NaCl solution) was especially highlighted. The microstructure presented the following change: equiaxed BCC (Body Centered Cubic) grains + fine MC (carbide, M = Al, Cr, Co and Ni) particles (x = 0) → equiaxed BCC grains + coarse TaC blocks + fine TaC particles (x = 0.5) → flower-like BCC grains + coarse TaC blocks + eutecticum (BCC + TaC) (x = 1.0). The average microhardness of the coatings demonstrated an upward tendency with increasing x due to the combination of the stronger solid solution and dispersion strengthening from the significant difference in atomic radius between Ta and Fe and the formation of TaC with an extremely high hardness. The wear rates of the coatings were gradually reduced both in air and in NaCl solution along with the increase in Ta content, which were lower than those of the substrate. The wear rates of the coatings with x = 0.5 and 1.0 in NaCl solution were slightly reduced by about 17% and 12% when compared with those in air. However, the values of the substrate and the coating without Ta in NaCl solution were sharply enhanced by 191% and 123% when compared with those in air. This indicated that the introduction of Ta contributed to the improvement in wear resistance both in air and in NaCl solution.

Effect of Ta Content on High Temperature Creep Deformation Behaviors and Properties of PM Nickel Base Superalloys

Effect of Ta Content on High Temperature Creep Deformation Behaviors and Properties of PM Nickel Base Superalloys

Effects of Ta content on phase transformation in selective laser melting processed Ti-13Nb-13Zr alloy and its correlation with elastic properties

The phase transformation (β→ω and ω→α+β) and its correlation with the elastic properties of the selective laser melting (SLM) processed Ti-13Nb-13Zr-[0–8]Ta (wt.%) alloys were investigated. Analysis of the ω phase formation revealed that when the content of Ta is less than 6%, the formation of ω phase increases with the increase of Ta content in the alloys, while the high content of Ta (8 wt%) suppresses the ω phase formation. The elastic modulus of the alloys increases first and then decreases with the increase of Ta content due to the subsequent changes in the amount of ω phase. However, the ω phase is decomposed into α and β phases after solution treated and the elastic modulus of the alloys is decreased with the increase of Ta. Furthermore, the orientation relationship of O’ phase with β phase was discussed by black field transmission electron microscopy and selected-area electron diffraction.

Effect of Ta content and sintering temperature on characteristics of nanocrystalline Cu-Ta nanocomposite

In this study, the microstructural, physical and mechanical properties of the nanocrystalline Cu-Ta material synthesized by mechanical milling and subsequent sintering were investigated affected by Ta content and sintering temperature. Scanning electron microscope and X-ray diffraction results showed that increasing Ta content from 1 to 5 wt% changed the material behavior during milling and resulted in reduction of powder particle size and crystallite size. For the sintered specimens, addition of Ta decreased the electrical conductivity due to reduced density and increased electron scattering effect while micro-hardness of Cu matrix was promoted. The higher sintering temperature about 850 °C also increased density and provided more segregation of Ta which was led to improvement in both micro-hardness and electrical conductivity of Cu-Ta composite. In addition, a comparison between sintering process at 850 °C by SPS method and conventional cold pressing- sintering revealed that SPS has a high potential to enhance physical and mechanical properties.

Effects of Ta Content on Thermodynamic Properties and Transformation Temperatures of Shape Memory NiTi Alloy

In the present work, Ni32-x-Ti-Ta18+x (x = 0, 2, 3, 4, 5, 6, 7, 8) shape memory alloys, produced by arc-melting method. Then, differential scanning calorimetry (DSC), optical microscopy (OM), x-ray diffraction (XRD), and Vickers micro-hardness measurements were carried out to investigate thermodynamic parameters, microstructure, crystal structure, and mechanical properties of the alloys, respectively. The DSC results showed that, as the amount of Ta increased, the phase transformation temperatures of the specimens significantly changed. In addition, increasing of Ta composition raised the mass density and electron participation of NiTi alloy, and thus, the vibrational term of entropy overcomes the electron participation; consequently, the total entropy declined in the alloys. It is found that OM images possess a dendritic microstructure, where by increasing the amount of Ta, the dendrites length increase while random orientations decrease. Moreover, XRD patterns exhibited the existence of each austenite phase (B2), martensite phase (B19ʹ), and β-Ta riched phase in all samples.

Effect of Ta content on the magnetic susceptibility of Zr–Ta binary alloys preventing artefacts for MRI

The microstructures and magnetic properties of Zr–Ta binary alloys were examined in the study presented here. The Zr–Ta alloys (Zr-(0–50) mass% Ta) were prepared from 99.5 mass% zirconium and 99.5 mass% tantalum by arc melting in an Ar atmosphere. Magnetic susceptibility was evaluated in air at room temperature. The phase constitutions were identified using an X-ray diffractometer (XRD), a scanning electron microscope (SEM), and a transmission electron microscope (TEM). The acicular martensitic phase formed mainly in the lower Ta composition. In Zr-25Ta and above, the volume fraction of the β-Ta phase increased as Ta concentrations increased. TEM observations showed phase separation due to spinodal decomposition in Zr-20Ta and 30Ta. The diffraction patterns for Zr-20Ta showed spots associated with the ω phase. Magnetic susceptibility gradually declined as Ta was added, falling to a minimum twice: near Zr-20Ta and 50Ta. The former minimum resulted from the high volume fraction of the ω phase having lower magnetic susceptibility than that of other phases. The latter resulted from the formation of the β-Ta phase with magnetic susceptibility lower than the β-Zr phase. As a result, Zr–Ta alloys showed about three times lower magnetic susceptibility than Ti alloys and would be suitable for use with medical devices in MRI environments.

Effect of Ta content on microstructure, hardness and oxidation resistance of TiAlTaN coatings

Ti1−x−yAlxTayN coatings with various Ta contents (y=0.00–0.37) have been prepared by magnetron sputtering. Scanning electronic microscopy results show that the increased Ta content makes Ti1−x−yAlxTayN coatings more compact and exhibit a finer columnar structure. X-ray diffraction results show that the preferred orientation of Ti1−x−yAlxTayN coatings changes from (111) to (200) with increasing Ta content. Nanoindention results indicate that the hardness of the coatings sharply increases from 11GPa without Ta to 31.2GPa at y=0.21. Solution strengthening caused by doping Ta is the main reason for the rapid increase of hardness. After oxidation in ambient air, Ti0·44Al0.56N coating is fully oxidized to α-TiO2 and γ-TiO2 at 600°C. A significant increase of oxidation resistance for Ti0·37Al0.42Ta0.21N coating has been observed at 800°C. However, a higher Ta content (y=0.37) is not conducive to retard the formation of α-TiO2 phase at low temperature, but will increase lattice distortion. This can make the coating easy to spall during further oxidation.

High selectivity of TaSiBEA zeolite catalysts in 1,3-butadiene production from ethanol and acetaldehyde mixture

New tantalum-silica based zeolite catalysts (TaSiBEA) were applied in this work for 1,3-butadiene production from ethanol. Tantalum incorporation into vacant T-atom sites of the SiBEA zeolites framework as mononuclear Ta(V) allowed preparing highly selective catalysts for ethanol/acetaldehyde mixture conversion into 1,3-butadiene, with selectivity to 1,3-butadiene of 80–90% at total conversion of the mixture of 45–30%. Effect of Ta content on activity of TaSiBEA zeolite catalysts and the ethanol/acetaldehyde molar ratio in selective production of 1,3-butadiene were demonstrated.

Effects of Ta Content on the Electrical Properties of Lead-Free (K0.44Na0.52Li0.04)(Nb0.96-xTaxSb0.04)O3 Ceramics

Lead-free piezoelectric ceramics with the composition of (K0.44Na0.52Li0.04)(Nb0.96-xTaxSb0.04)O3 (KNLNTxS) were prepared by the conventional solid-state reaction method. The effects of Ta content on the phase structure, microstructure and electrical properties of KNLNTxS ceramics were investigated. The effect of poling temperature on piezoelectric properties of KNLNTxS ceramics was also studied in detail. Enhanced piezoelectric properties (d33 = 315 pC/N, kp = 0.49 and kt = 0.48) with low dielectric loss (tanδ < 0.06) were obtained in the ceramics with x = 0.10 under optimum poling temperature (140°C), indicating that KNLNTxS ceramic is a promising lead-free piezoelectric candidate material.