Effect Of Ta Addition Research Articles

Effects of Ta Addition on the Microstructure, Compression Properties and Oxidation Resistance of NiAl-Cr(Mo) Alloy

Effects of Ta Addition on the Microstructure, Compression Properties and Oxidation Resistance of NiAl-Cr(Mo) Alloy

Effect of Ta addition on primary MC carbide in Ti-Nb-Mo-W-alloyed superalloy

The effect of Ta addition on characterization of primary MC carbides with regard to their morphology, composition, and size in Ti-Nb-Mo-W-alloyed Ni-based superalloy were investigated. Several tools including automated scanning electron microscopy as well as electrolytic etching technology were used for broad characterization of carbides including three-dimensional morphology. The addition of Ta significantly influences the composition and morphology of primary MC carbides. Large dendrite (Ti,Nb,W,Mo)C carbides were changed to smaller (Ta,Ti,Nb)C carbides. The hardness of both MC primary carbides and the matrix were increased. MC carbides in the studied superalloys were developed dendrite in three-dimensional morphology, which was much larger than that in two-dimensional morphology. The formation mechanism of carbides was clarified by thermodynamic calculation.

Revealing effects of solute Ta on solidification and precipitation of Al-7Si-0.3Mg based alloys

Effect of Ta additions up to 0.12 wt.% on the grain refinement and the stability of β-MgSi series precipitates of Al-7Si-0.3Mg based alloys was investigated. It was found that (i) Ta can replace Ti for an effective grain refinement of Al-7Si-0.3Mg based alloys. Similar to the case of free Ti, a Ta-rich layer on the interface (basal plane) of TiB2 was observed by using TEM and further supported by DFT calculation, while no significant interaction of Ta with other solutes (i.e. Si) was observed. More interestingly, Ta partitions into TiB2, forming (Ti,Ta)B2, which was observed for the first time in this alloy system. With the addition of 0.12 wt.% Ta, the grain size of primary Al can be refined down to 150 µm. More importantly, the eutectic grain size can be also refined down to 1500 µm even after Sr modification. (ii) DFT calculation shows that Ta stabilizes the β-MgSi series precipitates, while no significant effect of Ta on activation energy of β-MgSi precipitates was observed by using DSC due to its low concentrations. But, the activation energy follows an ascending order, i.e., β''-MgSi < β-MgSi. (iii) TEM shows that the dominant strengthening effect is related to the β''-MgSi precipitate. DFT indicates that Ta can improve the stability of the β''-MgSi precipitate. DSC confirms that Ta can enhance the precipitation kinetics of the β''-MgSi precipitate. This investigation can provide a novel methodology to control solidification and precipitation microstructure of Al-7Si-0.3Mg based alloys via the addition of Ta.

Investigation into Corrosive Wear of the CoCrFeNiTax Laser-Clad Coatings on TC4 in the Neutral and Alkaline Circumstance

CoCrFeNiTax (x = 0, 1) coatings were prepared on the surface of TC4 by laser-cladding to improve the corrosive wear property of TC4 and extend its service life in corrosive media, ultimately aiming to improve its surface performance. The effects of Ta addition on the phase constituent and microstructure of the coatings were first investigated. Given the wide application of TC4 in corrosive media (even undergoing friction), the corrosive wear of TC4 covered with the coatings was especially focused in two media (neutral and alkaline). The results showed that the coatings were composed of primary α(Ti) and eutecticum (α(Ti) + Ti2Ni) as the matrix and TiC as the reinforcement. The introduction of Ta increased the volume fraction of eutecticum and TiC and made the microstructure more uniform. The coating with Ta performed more outstanding corrosive wear resistance than the other two samples in the two media. The wear rate of the coating with Ta was 4.7458 × 10−4 mm3·N−1·m−1 in the neutral environment and 6.6808 × 10−4 mm3·N−1·m−1 in the alkaline environment, 64.45% and 61.79% lower than those of TC4, respectively. The wear mechanism of the samples is a combination of serious micro-cutting, active dissolution, and oxidation, and the introduction of Ta effectively improved the resistance to micro-cutting.

The effect of Ta addition on mechanical properties of Zr-based bulk metallic glasses

Bulk metallic glasses (BMGs) exhibit poor room temperature plasticity, so improving their room temperature plasticity is important for amorphous alloys in engineering applications. In this paper, Zr60Cu(20-x)Al10Ni10Tax (x = 0, 1, 3, 5) bulk metallic glasses with 3 mm diameter rods were prepared by water-cooled copper mold suction casting, and investigated the effect of minor additions of Ta on the properties of Zr–Cu–Ni–Al alloys, especially on plasticity. The results show that the Zr-based alloys with a 3 mm diameter are amorphous. With the addition of Ta elements, the glass transition temperature hardly changed, the crystallization onset temperature increased from 747 K to 767 K, the width of the supercooled liquid phase zone increased from 49 K to 68 K, and the thermal stability of the alloy was improved. The room temperature uniaxial compression test found that with the increase of Ta content, the strength and plasticity of alloys showed a trend of first increasing and then decreasing, when the Ta content was 1 at.%, more interactive shear bands were observed on the side surface of the alloy after compression, while the fracture surface exhibited a complete vein pattern, and fracture strength and plasticity of samples reached to 1920 MPa and 13.8%, respectively. The results of nanoindentation tests indicated that when the Ta content was 1 at.%, the alloy exhibited the maximum indentation hardness and elastic modulus of 8.03 GPa and 101.48 GPa, respectively. It can be concluded that the right amount of Ta in Zr-based BMGs improves the mechanical properties, especially, the fracture strength, the plasticity, the indentation hardness, and the elastic modulus.

Effect of Ta addition on the sinterability of spark plasma sintered W-Ni-Fe alloy

The purpose of this research is to investigate and characterize the W-Ni-Fe-Ta compositions by solid-state sintering using the Spark Plasma Sintering (SPS) technique at a relatively lower temperature. The sinterability of W-Ni-Fe ternary tungsten heavy alloy (WHA) with the addition of Tantalum in predetermined compositions was sintered using SPS at 1100°C under 30 MPa pressure. The effect of Ta addition on WHA densification, microstructure, and mechanical properties was studied. Ni was found to act as an activator in the sintering of tungsten. SEM and energy dispersive spectroscopy revealed an even distribution of Ta in the W and Ni-Fe matrix. The data of hardness and ultimate tensile strength were explained using grain size, contiguity, and the formation of brittle intermetallic phases. W-7Ni-3Fe-5Ta alloy composition has the highest ultimate tensile strength of 870 MPa, 189.2 HV0.5kgf hardness, and 83.42% relative sintered density. During the tensile test, W grain cleavage fracture, W-W decohesion, matrix tearing, and W matrix intergranular types of fracture surface were observed.

The Effect of Ta Additions on a Low γ′ Volume Fraction Ni–Fe Base Superalloy System

The Effect of Ta Additions on a Low γ′ Volume Fraction Ni–Fe Base Superalloy System

Developing Ti-Al-Ta-N based coatings: Thermal stability, oxidation resistance, machining performance and adaptive behavior under extreme tribological conditions

Application of hard coatings was found to be a promising method in response to industry’s growing demand for improved productivity and avoiding high temperature in cutting zone. This study presents comprehensive investigations on the effect of Ta addition into TiAlN coating on mechanical properties, oxidation resistance, thermal stability, and ultra-high speed machining performance. The thermal stability of the coatings was studied using DSC, heat treatment between 900 and 1400 °C, and X-ray diffraction (XRD). Isothermal oxidation testing was performed at 1000 °C for 0.5 and 20 h in synthetic air followed by cross-section examination using field emission scanning electron microscopy (FE-SEM). The features of the chip formation were studied using SEM and electron backscattered diffraction (EBSD). Evidence of spinodal decomposition was found in the XRD patterns. However, the age-hardening effect was different in its degree of significance for monolayered and multilayered TiAlTaN coatings. Monolayered TiAlTaN coatings exhibited the best oxidation resistance, while Ta-free multilayered coatings fully oxidized after 20 h of exposure to 1000 °C temperatures. Tool life measurements showed a ~25% improvement for monolayered TiAlTaN coating compared to TiAlN under intense machining conditions and indicated that the addition of Ta in the coating greatly delayed the progression of crater wear and subsequent substrate exposure. This is attributed to the formation of protective tribo-oxide layers on the friction surface, the tool with monolayer TiAlTaN coating demonstrated optimal chip properties, resulting in improved metal flow at the chip’s undersurface. Ultimately, a lower fraction of recrystallization was found in EBSD images of chip cross-sections, indicating lower heat transfer and plastic deformation. This study showed a significant improvement in mechanical properties, thermal stability, oxidation resistance along with more than 25% improvement in high-speed machining performance induced by Ta addition into TiAlN coatings.

Effect of Ta addition on solidification microstructure and element segregation of IN617B nickel-base superalloy

IN617B nickel-base superalloy is considered as a good candidate material in 700 °C advanced ultra- supercritical coal-fired power plants. The effect of Ta addition on solidification microstructure and element segregation of IN617B alloy was investigated by OM, SEM, TEM, EDS, EPMA and thermodynamic calculation. The results showed that the solidification microstructure exhibited a dendritic segregation pattern with many primary carbides distributed in interdendritic regions, such as network M6C, lath M23C6 and granular Ti(C,N). The addition of Ta promoted the precipitation of Ta-rich MC significantly inhibiting the precipitation of M6C and M23C6, and reduced the segregation degree of Al, Mo and Ti alloying elements. The addition of Ta decreased the melting temperature of MC carbide, but did not impact the solidification path, that was, L→ γ matrix → MC or Ti(C,N) → M6C → M23C6, where MC and Ti(C,N) tended to form symbiotic microstructure with M6C. This study will provide theoretical basis and data support for the alloy optimization and casting structure control of IN617B nickel-based superalloy.

Effect of Ta Addition on the Oxide Layer Evolution of Ni-16cr and Ni-20cr Alloys at 1000 °C in Air

Effect of Ta Addition on the Oxide Layer Evolution of Ni-16cr and Ni-20cr Alloys at 1000 °C in Air

Effect of Ta addition on microstructures, mechanical and damping properties of Cu–Al–Mn–Ti alloy

Cu–Al–Mn–Ti–xTa alloys (x = 0, 1, 2, 3, wt.%) prepared by spark plasma sintering were investigated for the effect of Ta content on the microstructure, mechanical and damping properties. The microstructure and phase composition indicate that the alloy is mainly composed of β′1 martensite, γ′1 martensite, Ti-rich and Ta-rich phase. As the Ta content increases, the grain size of the alloy first decreases and then increases. The reverse trend was observed for hardness, tensile and compressive strength. The hardness, tensile strength and compressive strength increased by 18.2%, 44.9% and 28%, respectively, when the Ta content was 1 wt.% compared to the alloy without Ta element. The presence of martensite provides the alloy with promising damping properties. Meanwhile, the formation of the second phase has a two-sided effect on the damping characteristics. That is, the increase in grain boundaries provides more interfaces for energy dissipation, but the increased compressive stress between the interfaces also hinders the movement of the interfaces. Excellent damping performance is demonstrated with the addition of 1 wt.% of Ta element. The peak values of damping capacity at room temperature and at about 580 °C reached 0.026 and 0.19, respectively. The results confirm that the addition of Ta elements is achievable to obtain Cu–Al–Mn–Ti alloys with both high mechanical and damping properties.

Tailoring the microstructure and magnetic properties of (Nd,Pr)2Fe14B/α-Fe nanocomposite magnets via Ta addition

The effect of Ta addition on the microstructure and magnetic properties of (Nd0.4Pr0.6)9Fe85-xTaxB6 nanocomposite magnets prepared by melt spinning was studied. Microstructure studies reveal that Ta addition is effective in refining the microstructure of nanocomposite magnets. The temperature coefficient of coercivity (β) is improved from −0.350%/°C for x = 0 to −0.329%/°C for x = 2 in the temperature range 27 °C-175 °C. With the increase in x from 0 to 2, the coercivity of the alloys is improved remarkably from 6.1 kOe to 10.4 kOe at the expense of remanence. As a result, the optimal magnetic properties with Hci = 7.5 kOe and (BH)max = 23.4 MGOe have been achieved at x = 1. Minor hysteresis loops were analyzed to determine the coercivity of (Nd0.4Pr0.6)9Fe85-xTaxB6 nanocomposite magnets by inhomogeneous domain wall pinning mechanism. The significant enhancement of magnetic properties mainly results from grain refinement achieved by introducing Ta.

Microstructure and properties of Ta-reinforced NiCuBSi + WC composite coating deposited on 5Cr5MoSiV1 steel substrate by laser cladding

Mixtures of Ni-based self-fluxing alloy + WC powders are widely used to prepare wear-resistant coatings on workpiece surfaces, and the particle size and distribution of the WC reinforcing phase affect the wear resistance and uniformity of the coatings. Here, to improve the wear resistance of the shield machine cutter ring, Ta was used as the reinforcing phase for the NiCuBSi + WC composite powders for the first time, and the wear-resistant coatings were prepared on the surface of 5Cr5MoSiV1 steel by laser cladding. The effect of Ta addition on the structure and properties of the coating was investigated, and the mechanism of Ta modification was analyzed. The results show that a good metallurgical bonding is formed between the steel substrate and the coating. Without the addition of Ta, the main reinforcing phases in the coating are large spherical WC particles and small flocculated WC and W2C particles, and the binding phase is Ni-Cu. The distribution of spherical WC large particles in the coating is not uniform, and there are Ni-based columnar crystal regions without the reinforcing phase. The addition of Ta consumed some of the spherical WC particles in the coating and took away some of the C of the WC particles to synthesize TaC in-situ, generating long rod-shaped W2C particles and embedding them in the coating, improving the uniformity of the hardness distribution of the coating. The wear resistance of the coating is 2.3 times higher than that without the addition of Ta, which is expected to improve the wear resistance of the cutter ring of the shielding tunneling machine.

Effect of Ta Addition on the Microstructure and Tensile Properties of a Ni-Co Base Superalloy

Herein, the effect of Ta addition (0 and 2 wt pct) on the tensile properties of a Ni-Co base superalloy was investigated in the temperature range of 23–900 °C. The results revealed that the addition of Ta improved the strength of the superalloy at all experimental temperatures and increased the plasticity at 760 °C. In addition, the microstructural observations indicate that Ta addition promoted the precipitation of γ′ precipitates, as well as the precipitation of (Ta, Ti)-rich MC carbides. The addition of 2 wt pct Ta promoted twinning and, thus, transformed the fracture mechanism of the alloy from an intergranular brittle fracture to a mixed ductile and brittle fracture at 760 °C. Furthermore, the tensile properties and the related microstructures, deformation mechanisms, and fracture mechanisms of the experimental alloys are discussed. Finally, we demonstrated that the combined effect of the increase in the grain boundary strength, the reduction in the critical resolved shear stress, and the promotion of twinning induced the synchronous improvement of strength and plasticity of the alloy at 760 °C.

Tribocorrosion behavior of Ti64-xTa alloys fabricated through powder metallurgy

The tribocorrosion behavior in simulated-body fluid of Ti64-xTa (x = 5, 15 and 30 vol%) alloys fabricated by means of powder metallurgy was evaluated. Ti64-xTa alloys demonstrated a better passivation behavior in comparison to Ti64, forming a more stable passive film. In addition, an important increment in the polarization resistance, and a decrement in the corrosion rate were observed as an effect of Ta addition. Larger corrosion potential drops during tribocorrosion tests indicated that the passive films formed on Ti64-xTa alloys surface were easily removed as the Ta amount increased. Moreover, despite the detrimental in the mechanical properties caused by the addition of Ta, alloys containing 5 and 15 vol% of Ta improved the wear rate of Ti64. The results demonstrated that Ti64 alloys with low Ta amounts fabricated through powder metallurgy are potentially suitable for short-term implant applications.

Effect of Ta addition on the fuzz formation of additively manufactured W-based materials

As a divertor plasma-facing material, W will experience high-flux plasma irradiation. In particular, severe surface morphology change like fuzz formation can be induced by He plasma irradiation. In this study, fuzz formation on additively manufactured W and W–Ta was investigated. Rolled W, laser-powder-bed-fused (LPBFed) W and W–Ta were exposed to high flux (∼1023 m−2 s−1) He plasma in the linear plasma generator Magnum-PSI with ion energy 12–13 eV at 1273 K. The mean thickness of the fuzz at grain interiors of rolled W, LPBFed W and W–Ta was measured as 0.37 μm, 0.71 μm and 0.23 μm, respectively. The fuzz suppression in LPBFed W–Ta can be attributed to the synergetic effect of solid-solution, dislocation, and secondary-phase nanoparticles. Abnormally grown fuzz was observed near the pre-existing cracks of LPBFed W, while no such structure was found in LPBFed W–Ta. It is found that dislocations play a crucial role in inhibiting fuzz growth. This is confirmed by the difference in fuzz structure in rolled W and LPBFed W, where rolled W has a much greater dislocation density compared to LPBFed W. This work suggests that the fuzz growth kinetics may be tuned by tailoring the microstructures using the LPBF technique.

Effect of Ta addition on solidification characteristics of CoCrFeNiTax eutectic high entropy alloys

Effect of Ta addition on solidification characteristics of CoCrFeNiTax (x = 0.1–0.7) eutectic high entropy alloys were investigated. With increasing Ta content, CoCrFeNiTax alloys changed from hypoeutectic alloys with primary γ phase to eutectic alloy (x = 0.43) and to hypereutectic alloys with primary Laves phase. Consequently, Ta content in primary phase significantly increased, while the content of Ta element in γ/Laves eutectic phases slightly decreased. Meanwhile, the solidification path and solidification characteristic temperatures of CoCrFeNiTax alloys both agreed with typical binary eutectic phase diagram, and obvious microsegregation of Ta element was only found in CoCrFeNiTa0.1 alloy. Furthermore, the contents of Co, Cr, Fe and Ni elements in primary phases and distribution behaviors of Co, Cr, Fe and Ni elements were both different in CoCrFeNiTax alloys, which indicated that CoCrFeNiTax alloys cannot be simplified as (CoCrFeNi)–Ta pseudo binary system when analyzing distribution behaviors of Co, Cr, Fe and Ni elements.

The effect of Ta additions on the oxidation resistance of SPS-produced TiAl alloys

The influence of the environment on the properties of TiAl alloys is a concern for elevated temperature applications. One element that stands out in improving the resistance of TiAl alloys against high-temperature oxidation is Nb. Nb promotes the activities of Al and favors the formation of a more protective Al2O3 surface oxide which subsequently stymies oxygen diffusion to the alloy. Ta is an equal replacement of Nb. Thus, this study aims to evaluate the effect of 0.8, 4, and 8 at. % Ta additions on the oxidation resistance of spark plasma sintered Ti-46.5Al (at. %) alloy. Isothermal oxidation tests were carried out for 360 and 100 h at 1123 and 1273 K respectively. Surface oxides examination include scanning electron microscopy with energy-dispersive X-ray spectroscopy and X-ray diffractometry. The results show that 4 and 8 at. % Ta additions significantly support the formation of an interconnected, non-porous Al2O3 layer at the metal-oxide interface. The continuous non-porous Al2O3 layer serves as a diffusion barrier which leads to superior oxidation resistance of the TiAl alloys.

Effects of Ta Addition on the Microstructure and Mechanical Properties of CoCu0.5FeNi High-Entropy Alloy

In this work, the alloying effects of Ta element on the microstructure evolution and mechanical properties of CoCu0.5FeNiTax (x = 0-0.6 at.%) high-entropy alloys were studied. The microstructure changed from single solid solution to hypoeutectic, then to eutectic, and finally to hypereutectic with the increase in Ta content, which is because Ta element facilitates the Laves phase to form. The volume fraction of hard and brittle Laves phase increases with the Ta content, which increases the yield strength, Vickers hardness and theoretical density but decreases the plastic strain. The CoCu0.5FeNiTa0.1 alloy with a single FCC solid solution structure shows the optimal balance between density and ductility. The theoretical density and tensile fracture strain can reach 8.94 g/cm3 and 36.3%, respectively.

Health Promotion through Integrative Health Practices

In this work, in situ bi-phase (TiB2-TiCxNy)/(Ni-Ta) cermets were fabricated via a combined combustion synthesis and hot-pressing (CSHP) method in a Ni-Ti-BN-B4C-Ta system. The effects of Ta addition on the reaction process, phase constituents, microstructures and mechanical properties of the (TiB2-TiCxNy)/(Ni-Ta) cermets were studied. Ta is shown to dilute the system and lead to a small number of intermediate phases (Ni20Ti3B6 and Ni3Ti) that are retained in the products. Furthermore, the addition of Ta can markedly refine the ceramic particles and decrease the size and quantity of voids. The evaluation of the mechanical properties revealed that an increase in the Ta content resulted in increases in the compression strength (σUCS) and hardness and that the fracture strain (εf) increased first and then decreased. The cermet with the optimal addition of 5 wt% Ta possessed the best mechanical properties without decreasing the value of εf (2.9%). The addition of 5 wt% Ta resulted in a compressive strength of 3.37 GPa and the highest hardness of 1909 Hv, which is an increase of ~16% and ~22%, respectively, compared to cermets without added Ta.