Elements Ti Research Articles

Fabrication of Zn and Ti-loaded Carbon-silica Composite Derived from Gelatin Template for the Photodegradation of Methylene Blue

Carbon-silica nanocomposites (CSNs) from gelatin as a carbon source and natural template and TEOS as a silica source have been successfully synthesized and impregnated into ZnO and TiO2 photocatalysts. The structural, morphological, and textural properties and photocatalytic activity for methylene blue degradation of TiO2/CSNs and ZnO/CSNs were investigated. XRD data revealed that TiO2/CSNs and ZnO/CSNs had different structural characteristics with similar crystallinity. FTIR spectra demonstrated the presence of Zn–O and Ti–OC bonds, respectively, at about 500-450 cm-1 and 1500 cm-1. The morphological surface exhibited stacked tubular shapes of TiO2/CSNs and ZnO/CSNs with the primary elements of Ti, Zn, Si, C, and O. The nitrogen adsorption-desorption curves revealed both micropores and mesopores of TiO2/CSNs and ZnO/CSNs where the surface area reduced due to the blocking pore after impregnation. Moreover, ZnO/CSNs verified a higher degradation percentage against methylene blue than that of TiO2/CSNs. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Influence of Al and Ti Alloying and Annealing on the Microstructure and Compressive Properties of Cr-Fe-Ni Multi-Principal Element Alloy

This study meticulously examines the influence of aluminum (Al) and titanium (Ti) on the genesis of self-generated ordered phases in high-entropy alloys (HEAs), a class of materials that has garnered considerable attention due to their exceptional multifunctionality and versatile compositional palette. By meticulously tuning the concentrations of Al and Ti, this research delves into the modulation of the in situ self-generated ordered phases’ quantity and distribution within the alloy matrix. The annealing heat treatment outcomes revealed that the strategic incorporation of Al and Ti elements facilitates a phase transformation in the Cr-Fe-Ni medium-entropy alloy, transitioning from a BCC (body-centered cubic) phase to a BCC + FCC (face-centered cubic) phase. Concurrently, this manipulation precipitates the emergence of novel phases, including B2, L21, and σ. This orchestrated phase evolution enacts a synergistic enhancement in mechanical properties through second-phase strengthening and solid solution strengthening, culminating in a marked improvement in the compressive properties of the HEA.

Effect of Sulfurization Temperature on Properties of Cu2ZnSnS4 Thin Films and Diffusion of Ti Substrate Elements

The addition of flexible Cu2ZnSnS4 (CZTS) thin film solar cells to titanium (Ti) substrates is an attractive way to achieve the low-cost manufacturing of photovoltaics. Prior research has indicated that the appropriate diffusion of Ti elements can enhance the crystalline growth of CZTS films. However, the excessive diffusion of Ti has been shown to adversely affect the photovoltaic performance of CZTS photovoltaic devices. Therefore, it is essential to regulate the diffusion of Ti elements within CZTS thin films to optimize their photovoltaic properties. The tendency for Ti substrate elements to diffuse into CZTS films is also influenced by the activation energy associated with these Ti elements. The sulfurization temperature is posited to be a critical factor in modulating the diffusion and activation energy of Ti elements within CZTS thin films. Consequently, this research investigates the alteration of the sulfurization temperature of CZTS thin films in order to enhance the properties of these thin films and to examine the diffusion behavior of titanium elements. The results reveal that as the sulfurization temperature increases, the diffusion of Ti elements within the CZTS thin films initially increases, then decreases, and subsequently increases again. This pattern suggests that the diffusion of Ti elements is affected not only by the activation energy of the Ti elements but also by the defect hopping distance within the CZTS thin films. Notably, at a sulfurization temperature of 550 °C, the grains at the base of the CZTS thin film demonstrate an increased density, which is associated with a reduced defect hopping distance, thereby hindering the diffusion of Ti elements within the CZTS thin films. Furthermore, at this specific sulfurization temperature, the slope of the current–voltage (I–V) curve for the CZTS/Ti structure reaches its maximum, indicating optimal ohmic contact characteristics.

Microstructural evolution and mechanical properties of Al-4Ni-0.4V alloyed with Zr and Ti at elevated temperatures

The influence of Zr and Ti alloying on the microstructural evolution and mechanical properties of an Al-4Ni-0.4V alloy at elevated temperatures was investigated. The results showed that the coarsening rate of the eutectic Al3Ni phase in the Al-4Ni-0.4V-0.2Zr-0.2Ti alloy decreased from 21.1 nm3/s in the Al-4Ni-0.4V alloy to 7.4 nm3/s after annealing at 350 °C for 0 h to 120 h. The tensile strength, yield strength, and elongation at room temperature of the annealed Al-4Ni-0.4V-0.2Zr-0.2Ti alloy (350 °C, 8 h) were 181 MPa, 108 MPa, and 27.2 %, respectively. After tensile test at 350 °C, these values of the annealed Al-4Ni-0.4V-0.2Zr-0.2Ti alloy were 108 MPa, 72 MPa, and 29.8 %, respectively. Transmission electron microscopy results revealed the precipitation of the L12 ordered structure of the Al3M (M = Zr, V, Ti) phase, approximately 2 nm in size, in the α-Al after annealing. These phases exhibited excellent lattice matching with the α-Al and considerable precipitation strengthening. Segregation of Zr, V, and Ti elements at the α-Al/Al3Ni interface hindered Ni diffusion in the matrix, thereby reducing Al3Ni phase coarsening. Moreover, the Al3M phase precipitated at the interface exhibited favorable matching with the lattice planes of the α-Al and Al3Ni phase, which improved the thermal stability of the eutectic structure and the mechanical properties at elevated temperatures.

Analyzing the Influence of Titanium Content in 5087 Aluminum Filler Wires on Metal Inert Gas Welding Joints of AA5083 Alloy

As the demand for lightweight structures in the transportation industry continues to rise, AA5083 aluminum alloy has become increasingly prominent due to its superior corrosion resistance and weldability. To facilitate the production of high-quality, intricate AA5083 components, 5087 aluminum filler wire is commonly utilized in metal inert gas (MIG) welding processes for industrial applications. The optimization of filler wire composition is critical to enhancing the mechanical properties of AA5083 MIG-welded joints. This study investigates the effects of modifying 5087 aluminum filler wires with different titanium (Ti) contents on the microstructure and weldability of AA5083 alloy plates using MIG welding. The influence of Ti contents was systematically analyzed through comprehensive characterization techniques. The findings reveal that the constitutional supercooling induced by the Ti element and the formation of Al3Ti facilitate the heterogeneous nucleation of α(Al), thereby promoting grain refinement. When the Ti content of 5087 filler wire is 0.1 wt.%, the grain size of the weld center was 78.48 μm. This microstructural enhancement results in the improved ductility of the AA5083 MIG-welded joints, with a maximum elongation of 16.64% achieved at 0.1 wt.% Ti addition. The hardness of the joints was the lowest in the weld center zone. This study provides critical insights into the role of Ti content in MIG welding and contributes to the advancement of high-performance filler wire formulations.

Competitive correlation between the interface layers determines the shear strength in Kovar/AgCuTi/Si3N4 joints

AbstractAs a promising high‐thermal‐conductivity ceramics, the direct bonding of Si3N4 with metals remains challenging. Here, we employed active metal brazing of Si3N4 ceramics and Kovar alloys using AgCuTi metal filler, and found that the shear strength in the prepared Kovar/AgCuTi/Si3N4 joints depends on the competitive correlation between the interface layers. The competitive consumption for active element Ti by Kovar/AgCuTi interfacial reactions reduced AgCuTi/Si3N4 interface layer thickness and deteriorated final shear strength, even when using a high‐Ti‐content filler. Surface analysis indicated that interfacial fracture between Ag‐based solid solution and Ti5Si3 was the primary cause of failure. Density functional theory (DFT) revealed that Ag (111)/Fe2Ti (001) interface had higher ideal work of adhesion (Wad) than Ag (111)/Ti5Si3 (001) interface, confirming the importance of AgCuTi/Si3N4 interface layer. Ultimately, by adjusting interface reaction layer thickness, the joints reached a high shear strength of 154.3 MPa.

Microstructure, hardness, and creep of Co-Fe-Ni-based high-entropy superalloy processed by laser powder-bed fusion

A Co-Fe-Ni-based high-entropy superalloy (29Co-29Fe-29Ni-4.3Al-4.3Ti-4.3 V, at.%) designed to form a γ/γ′ microstructure was fabricated via laser powder-bed fusion, utilizing a blend of elemental powders. The hardness and microstructure were compared in terms of laser processing parameters, heat treatment conditions, and fabrication methods. Lower volumetric energy density (45 J/mm³) for fusion favor the formation of swirl-shaped, partially-mixed regions. The extent of elemental enrichment and depletion varies from region to region, even within the same sample. Upon direct aging of these inhomogeneous as-built samples, γ′ precipitates form along cell boundaries, which is attributed to strong segregation of Ni and Ti elements at these boundaries. After homogenization of the as-built samples, a uniform distribution of fine γ′ precipitates is achieved through aging. The hardness of a homogenized traditionally-cast sample is lower than that of an as-built sample, owing to differences in grain size. Nevertheless, both samples aged under the same conditions exhibited a similar level of hardness, attributed to strengthening by the γ′ phase.

Superior strain-hardening and strength-ductility synergy by hierarchical L12 phases in a highly (Al, Ti)-added medium-entropy alloy

A novel precipitate-strengthened Co–Cr–Ni medium-entropy alloy with a pure “FCC + L12” dual-phase structure is developed by adding a high concentration (6 at.%) of Al and Ti elements. After aging heat treatment at 700 °C for 4 h, the hierarchical L12 phases, composed of primary large-sized L12 phases (∼70 nm) and secondary L12 particles (∼14 nm), are achieved. The designed alloy featuring hierarchical L12 phases exhibits excellent strength-ductility combinations and strain-hardening ability, properties that are much improved over their counterparts with homogeneous dispersed L12 phases (∼13 nm) and without L12 phases. Especially, the yield strength (1320 MPa), ultimate tensile strength (1886 MPa), and average strain-hardening rate (5.15 GPa) are obtained in the alloy with hierarchical L12 precipitates deformed at cryogenic temperature. The Orowan bypass mechanism of the primary L12 phases, along with the shearing mechanism of the secondary L12 phases, collectively contributes to the exceptional strength of the alloy with hierarchical L12 precipitates. The penetration of dislocations and stacking faults (SFs) in the primary L12 phases, combined with hetero-deformation-induced (HDI) hardening attributed to these hierarchical L12 precipitates, may be a key factor in improving strain-hardening properties of the alloy.

Variation of the Passive Film on Compositionally Concentrated Dual-Phase Al0.3Cr0.5Fe2Mn0.25Mo0.15Ni1.5Ti0.3 and Implications for Corrosion

AbstractThe passive film on a dual-phase Al0.3Cr0.5Fe2Mn0.25Mo0.15Ni1.5Ti0.3 FCC + Heusler (L21) compositionally concentrated alloy formed during extended exposure to an applied potential in the passive range in dilute chloride solution was characterized. Each phase, with its own distinct composition of passivating elements, formed unique passive films separated by a heterophase interface. High-resolution, surface sensitive characterization enabled chemical analysis of the passive film formed over individual phases. The film formed over the L21 phase had a higher concentration of Al, Ni, and Ti, while the film formed over FCC phase was of similar thickness but contained comparatively higher Cr, Fe, and Mo concentrations, consistent with the differences in bulk microstructure composition. The passive film was continuous across phase boundaries and the distribution of passivating elements (Al, Cr, and Ti) indicated both phases were independently passivated. Spatially resolved analysis of the surface chemistry of the dual-phase CCA revealed that the cation with the highest composition in passive film formed on the FCC phase was Cr (52.4 at. pct) and for the L21 phase was Ti (53.1 at. pct) despite the bulk concentration of each element being below 20 at. pct in their respective phases. Al, Cr, and Ti were enriched in both phases within the passive film relative to their respective bulk compositions. In parallel studies, single-phase alloys with compositions representative of the FCC and L21 phases were synthesized to evaluate the corrosion behavior of each phase in isolation. The corrosion behavior of the dual-phase alloy showed passivity evidenced by a pitting potential of 0.615 VSCE in 0.01 M NaCl. The pitting potential and other electrochemical parameters suggested a combination of behaviors of both single-phase samples, suggesting that the global corrosion behavior may be represented by a composite theory applied to phases, their area fractions, and interphase length. However, the interphase in the dual-phase CCA was a local corrosion initiation site and may limit localized corrosion protectiveness. The alloy design implications for optimization of second phase structure and morphology are discussed.

Study on welding process of stainless steel/superalloy dissimilar materials

Abstract In this study, dissimilar materials of 321 stainless steel, S-03 stainless steel, and GH3030 superalloy were selected and the argon tungsten-arc welding method was used to explore the welding parameters. The microstructure and properties of three materials after welding were studied. The main mechanism of welding cracks was analyzed by optical microscope and scanning electron microscope. Reasonable welding parameters were established and the dissimilar welding process was realized. The experimental results show that the cracks produced by welding of the three materials are typical welding hot cracks. The crack source originated from the bottom layer and extended to the surface of the welded joint. The main reason for cracking is the formation of low melting point compounds by the segregation of S and Ti elements during the process of self-melting. The welding process of the dissimilar materials can be realized by multi-pass filling welding. Increasing welding speed and reducing heat input are effective ways to improve weld mechanical properties of the welded joint.

Mechanics and Cutting Performance of Multilayer Nanostructured TiAlN/TiSiN/ZrN Coatings

The aerospace industry has made extensive use of titanium alloy material due to its exceptional qualities, which include high strength, low weight, and resistance to corrosion. However, these qualities also pose challenges for the material’s processing. This article examined the coated end mills for Ti6Al4V milling. First, an analysis was conducted on the solubility of Ti and Si elements. It was discovered that W and Co elements were far more soluble in Ti than Si and Zr elements, which could effectively stop element diffusion. Next, the base’s composition was planned. It was discovered that when the amount of Al increased, the base’s surface roughness increased, while its hardness and elastic modulus decreased. The binding force between the substrate and the base was greater at a 50:50 Ti:Al ratio. The H3/E2 was about 0.23 and the surface roughness was about 0.15 μm. TiSiN and TiSiN/ZrN functional layer properties were also examined. When Zr was added to TiSiN/ZrN coating, it improved the coating’s hardness and elastic modulus, increased density, and decreased surface roughness and friction coefficient when compared to TiSiN coating. There was an increase in hardness by 8.09% and an increase in elastic modulus by 9.65%. The average coefficient of friction decreased from 0.315 to 0.299. Lastly, an analysis of the initial and intermediate tool wear was done using the Ti6Al4V milling experiment. It was discovered that adding Zr element could successfully extend the tool’s cutting life by preventing adhesive wear.

The elemental variance between the "rice" and "non-rice" portions of Maifanitum and its health risk assessment

BackgroundMaifanitum, a mineral used in Chinese medicine, was first documented during the Song Dynasty (960-1279). Historical records suggest its multifaceted therapeutic properties, including detoxification and stasis resolution, necrosis removal and tissue regeneration, diuretic and calculi dissolution and prolonging life. The concentration of elements in Maifanitum may vary depending on its origin, different parts, which can affect its effectiveness in different fields of applications. Therefore, the analysis of elements in Maifanitum and the subsequent health risk assessment have been conducted. This provides an important basis for the quality control and application safety of Maifanitum. MethodThe analytical techniques employed in this study are inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES), utilized for the quantitative assessment of 60 elements (Refer to Appendix 1) within Maifanitum samples. Based on the test results, chemometric methods are employed to evaluate the characteristics and differences in elemental concentration from different sources and locations. Additionally, a preliminary health risk assessment is conducted for Maifanitum from different origins and various parts. ResultsWe have established a fingerprint of the elements within Maifanitum, demonstrating a commendable level of similarity. The findings from hierarchical cluster analysis（HCA） corroborated with those from principal component analysis (PCA), collectively unveiling a systematic profile of elemental disparities between Maifanitum samples of diverse origins and applications. It also revealed that there are differences in the concentration of Al, Ga, Be, Hf, Na, Sn, Ti, Zr, Gd, Tb, Sr, Pb, Ce, Ba and other elements in different parts of Maifanitum. While Cd, As, and Cu levels in all samples were within the permissible limits as defined by the Chinese Pharmacopeia, Pb concentrations in the majority of samples were found to surpass these standards, albeit slightly in the ''non-rice'' fraction. The assessment of both beneficial and deleterious elements indicates that the ''non-rice'' fraction of Maifanitum possesses superior quality attributes. Moreover, the overall concentration of rare earth elements in Maifanitum is substantially below the established lower threshold for daily human consumption, with no immediate evidence suggesting any adverse health risks. ConclusionThis study provides a basis for the quality control and safety evaluation of Maifanitum in clinical use.

Photonic device application of a self-driven MXene based nanocomposite

MXene based ternary composite photonic device was fabricated and characterized for the detection of different illuminations. The single chain polymer-cobalt phthallocyanine (SCP-CoPc) carrying metallised pthalocyanine macro ring was used as a polymer for the preparation of ternary composite. The Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) were used to differentiate MXene/ZnO/SCP-CoPc composite prepared. The presence of Ti, C, O, Zn and Co elements in the structure of the composite was confirmed by EDX. The electrical properties of planar interdigital coated MXene/ZnO/SCP-CoPc (1:1:1 by wt) were investigated for photovoltaic application. The photo-generated carriers contribute to the current flow, and the linear photoconductivity behaviour in current measurements with different illuminations such as 20, 40, 60, 80 and 100mW/cm2 indicates the possible photo device use of MXene/ZnO/SCP-CoPc nanocomposite. The photocurrent increased from 20mA/cm2 to 100mA/cm2 with the light intensity at 0.5V was tuned from 28 to 280 μA. The forbidden energy gap (Eg) value of the MXene/ZnO/SCP-CoPc ternary composite from optical measurements was was found to be 2.36eV. Experimental results showed that the presence of SCP-CoPc and ZnO (zinc oxide) in the ternary nanocomposite increased the ε' and ε" values of MXene. The ε′ and ε″ of the ternary composite is 13.0, 26217 at 1kHz and room temperature, respectively. The current-time results suggest that MXene based ternary composite photonic device is a self driven photodevice as the the device can detect light without any external voltage bias.

Exploring the effect of Ti doping on the friction characteristic of DLC films on the surface of pump plunger in petroleum extraction environments

DLC film is considered to be one of the most promising film materials for improving the abrasion resistance and operation life of pump plungers draw upon its low friction and high hardness, but the friction characteristics and mechanism of the doping element Ti on pump plungers under the petroleum extraction environment are still unclear. In this paper, the friction performance and mechanism of the doping Ti for DLC film on the appearance of the pump plunger under the petroleum extraction environment were investigated at the microscopic scale by using the reactive molecular dynamics. The outcome shows that the Ti-DLC displays a reduction in average friction force of 78.82 % and a decrease in average temperature of 40.33 % in the oil extraction environment, thus improving the abrasion resistance of the pump plunger. Moreover, with the increase of Ti content, the friction will gradually decrease, and significantly low friction behavior can be even materialized without lubrication. It is found that the main reason for the low friction of Ti-DLC film is that the layered structure determined by Ti concentration is formed on the appearance of friction pair, which inhibits the formation of interfacial carbon bond and reduces the shear stress on the contact surface.

Effect of Cr, Al and Mo additives on the wetting characteristics of molten Ni on (Ti, Zr, Hf, Nb, Ta)C high entropy ceramics

For the first time, the wetting behavior of the (Ti, Zr, Hf, Nb, Ta)C) high entropy carbide ceramics by molten Ni-based alloys was investigated using a sessile drop technique in a vacuum environment. Adding 10wt% of Cr, Mo, or Al into Ni resulted in final contact angles of 14°, 10°, and 14° on the (Ti, Zr, Hf, Nb, Ta)C substrate, respectively. The interaction mechanism between (Ti, Zr, Hf, Nb, Ta)C and Ni-based alloys occurs in two stages: the dissolution and interaction of the elements Ti, Zr, Hf with the alloys and the dissolution of NbC and TaC at the grain boundaries. SEM observations revealed that Cr and Al additives do not interact with carbides, while Mo was dissolved in carbides. Due to the low contact angle, minimal interaction region between alloy and ceramic, and short time of drop spreading, NiAl alloy is proven to be a promising binder for the HEC-based composites.

Effect of synthesis pressure on the properties of PcBN composites

Polycrystalline cubic boron nitride (PcBN) composites were synthesized under high-temperature and high-pressure (HPHT) conditions using TiC, Al and Ti as binders. This study explores the influence of varying synthesis pressures on the microstructure, interfacial bonding, densification, and mechanical properties of PcBN composites. The test results indicate that as synthesis pressure increased, the diffusion of Al and Ti elements to the surface of cBN particles was enhanced. This facilitates the migration of Ti atoms through the Al-rich matrix to the surface layer of cBN, thus accelerating the chemical interaction. At the highest pressure of 6 GPa, the hardness, flexural strength and fracture toughness of the samples achieved their maximum values: 3719 Hv, 1090 MPa, and 7.6 MPa.m1/2, respectively. Additionally, the material exhibits excellent cutting properties. Crack bridging, crack deflection, particle pullout and transgranular fracture were observed during the fracture process of the samples. Indicating strong interfacial bonding between cBN and the binder, which contributes to the material's enhanced toughness.

The microstructure and mechanical property of W-TiC/Ti composites via chemical-mechanical milling method

Carbide dispersion strengthened W(CDS-W) has attracted much attention as a plasma-facing material (PFM). However, the carbide tends to segregate at W grain boundaries and has poor interface properties with W due to the large difference in the bond structure. In this work, nanometer Ti was added to improve the performance of the W/TiC interface, and nanoscaled W-TiC-x%Ti (x=0.1,0.5 and 1.0) composites were prepared by chemical-mechanical milling and ordinary sintering method. The effects of Ti on powder morphology, phase composition, microstructure and mechanical properties were systematically investigated using XRD, SEM, EDS, TEM and HADDF technologies. Simultaneously, the existence form and distribution of Ti elements, and W/TiC interface characteristics of powders and composites were analyzed. Moreover, the microstructure evolution and strengthening mechanism were preliminarily discussed. Results show that the W-TiC/Ti powder has an obvious core-shell multilayer structure with a particle size range of 50-120 nm. The addition of Ti exists in the forms of TiC, Ti, and TiO2, and has no effect on the morphology and phase composition. Besides, the phase transformation and solution-precipitation of the Ti-added occurs during the sintering process. Part of Ti precipitates on the W/TiC surface to form Ti rich region, which significantly promotes the dispersion of TiC and improves the W/TiC interface, as well as prevents the growth of W grains, and the average grain size is 2.90 μm. Moreover, the orientation relationship of [013]( 00)TiCFCC||[ 13]( 0)WBCC exists at the W/TiC interface, especially the coherent phase interface is formed. The tensile strength and microhardness at room temperature are 520 MPa and 850 HV0.2, respectively, which is attributed to the synergistic effect of fine-grained strengthening, dispersion strengthening and interface strengthening. This work can provide a new strategy and direction for preparing high-performance CDS-W materials.

A novel negative thermal expansion ceramic network interlayer for releasing high residual stress of Cf/SiC heterogeneous brazed joint

Negative thermal expansion (NTE) ceramics have been widely concerned in adjusting the coefficient of thermal expansion (CTE) to release the high residual stress of heterogeneous joint. However, one major problem that needs to be solved is the agglomeration problem caused by excessive ceramic particles addition. In this work, a novel NTE ceramic Sc2W3O12 network interlayer is prepared by the polyurethane template method. The Sc2W3O12 network interlayer with a single NTE phase presents a three-dimensional network structure. The NTE Sc2W3O12 ceramic is uniformly distributed in brazing seam without agglomeration with the help of unique network structure. The active Ti elements play an important role in the interface bonding, reacted with Sc2W3O12 network interlayer and Cf/SiC composites to form Cu3Ti3O and TiC/Ti5Si3 reaction layer, respectively. After introducing Sc2W3O12 network interlayer, the CTE of the composite filler is reduced from 16.6 × 10−6 K−1 to 11.9 × 10−6 K−1, a decrease of 29 %. The highest shear strength of the Cf/SiC heterogeneous joint is reached 130 MPa, which is 5.4 times than that without Sc2W3O12 network interlayer.

Microstructure and mechanical properties of butt-welded Ti/steel bimetallic sheet using various multi-principal filler wires

Ti/steel bimetallic sheets have attracted significant attention in various engineering fields. However, achieving high-quality welded joints of Ti/steel bimetallic sheet presents difficulties because of poor metallurgical compatibility and different thermal expansion coefficients between titanium and steel. In this study, four types of multi-principal filler wires with varying contents of Cu, Ni, and Ti elements were designed and manufactured to finish the welding of TA2/Q235 bimetallic sheets. The study investigated the effects of various filler wires on the hardness, tensile strength, corrosion resistance, and microstructure of the welded joints. An interesting finding is that the highest tensile strength of 327±6 MPa was achieved in the welded joint using FeCoNi2Ti0.5 filler wire, with a joint coefficient of ∼79.1 %. The highest hardness in the weld zones was achieved by using FeCoNiTi0.5 filler wire, while the lowest hardness was achieved using FeCoNiCu0.5 filler wire. Dendrite (DR), interdendritic (ID), and eutectic structures were consistently observed in these weld zones. The phases of the DR and ID were identified as Fe2Ti and FCC structures based on EBSD data. A high content of Ni in filler wires could reduce the size and content of the Fe2Ti phase in the weld zones of Ti/steel bimetallic sheets.

Ab initio molecular dynamics investigation on hydrogen diffusion behavior in liquid aluminum alloy melts

In this work, ab initio molecular dynamics (AIMD) simulations under both NVT and NPT ensembles were performed to study the influence of alloying elements of Mg, Fe, Si, Ti, Cu, Zn, F, and Cl on the H diffusion behavior in liquid aluminum melt. It is found that the diffusion coefficient of H simulated by AIMD under the NVT model is highly consistent with the reported experimental results. Specifically, the addition of Cu, Cl, Si, and Zn is inclined to increase the diffusion coefficient of H in the melt, whereas the opposite result is observed with the addition of F, Fe, and Ti. Moreover, it is proved that the H diffusion coefficients are positively correlated with the H-Al bond lengths and the coordination number of H in a constant volume system. The obtained results deepen the understanding of the diffusion of H atoms in Al melts and contribute to the optimization of existing melt purification technologies.