Ti Content Research Articles

The comparative study of Ti-bearing oxides introduced by different methods

Abstract The Ti-bearing oxides are introduced into HRB400 steel melt through external addition method (EAM, TiO2) and internal precipitation method (IPM, Ti alloy) using a vacuum induction furnace, respectively. For each experiment, the instantaneous evolution of oxide properties was investigated through the analysis of intermediate samples. For the EAM method, it was found that the titanium content gradually increased with increase in the treatment time. Similar increasing trend is also observed for Ti-bearing oxide properties, such as the number density and normalized titanium content. These phenomena are totally different from those in the IPM intermediate samples, in which both Ti content and Ti-bearing oxide features show rapid increase, reaching saturation at 1 min after the addition of Ti alloy, and remain relatively stable thereafter. This comparison hints that after TiO2 addition, they first dissolve in molten steel, then decompose, and finally again form Ti-bearing oxides. Furthermore, in the case of similar titanium content, EAM intermediate samples exhibit higher Ti-bearing oxide number density and higher normalized titanium content compared to IPM samples. After heat treatment, the intragranular ferrite nucleation was observed in cast sample of EAM, which was induced by the introduced Ti-bearing oxides.

Combinatorial Property Mapping of Titanium‐Zirconium Thin Film Libraries as Screening for Medical Material Candidates

By employing a co‐sputtering technique, combinatorial thin film libraries in the Ti–Zr system are produced. The libraries have a compositional spread ranging from 40 to 70 at% Ti. The confocal geometry of the sputtering system is maintained for the production of all thin films. The microstructural and crystallographic properties are elucidated by energy dispersive X‐ray spectroscopy (EDX), X‐ray diffraction (XRD), and scanning electron microscopy (SEM) analysis. Furthermore, contact angle measurements and nanoindentations are performed to map the wettability, hardness, and elastic modulus of the alloy system. The electrochemical properties, i.e., the oxide film formation factor and the relative permittivity of anodically grown oxides on the parent metal alloys are determined. The measurements are performed in phosphate‐buffered saline in order to best simulate a biological environment. A linear shift in the properties is observed along the compositional gradient for the EDX, XRD, and SEM analysis. For all other sets of measurements deviations from the linear behavior, are observed around the 60 at% Ti concentrations. This coincides with the formation of a congruent alloy in bulk material. The observed changes however, deviated also from expectations for bulk alloys. The implications and potential for those alloys as implant material are discussed in the following.

Effect of TiO2 on catalytic performance of gold-titanium-catalyzed gas-phase epoxidation of propylene

The gas-phase epoxidation of propylene with H2/O2 is a promising method to generate propylene oxide (PO). Au/TS-1 is preferred catalyst due to the synergistic effect between Au nanoparticles and framework Ti species. TS-1 with high Ti content are used as support for Au catalysts, which are expected to achieve fantastic catalytic performance. However, their actual catalytic properties are generally unsatisfactory. The reason for this phenomenon is that the role of TiO2 in Ti-containing support is unclear. Here, we found that increasing TiO2 content in Ti-containing supports offered improving isoelectric point (IEP), which could be responsible for the obviously enhanced Au loading. More Au nanoparticles inserted into the TS-1 micropore favors their cooperation with framework Ti sites to realize higher C3H6 conversion. Simultaneously, propanal generated via direct propylene oxidation catalyzed by Au/TiO2 leads to the decrease of PO selectivity. A volcanic-shaped relationship between TiO2 content and PO formation rate is emerged.

The precipitation behavior of η phase with lamellar morphology in a newly designed K439B nickel-based superalloy

The microstructure of nickel-based superalloys significantly influences their mechanical properties and performance. The precipitation behavior of η phase during heat treatment of a newly designed K439B superalloy was studied. The results demonstrate that the precipitation temperature of η phase in this alloy varies from 1040 to 1070 °C. A detailed analysis of the microstructure indicates that the η phase exhibits a ∼10 nm lamellar structure, unlike the needle-like form reported in previous research. The γ' phase is distributed on both sides of the η phase, and the Ti content in the η phase is higher than that in the γ' phase, although the content of Al and Ti in the η and γ' phases are higher than that in the matrix γ phase. Moreover, the γ′ phase demonstrates an orientation relationship of {111}γ||{0001}η and [110]γ/γ′||[11—20]η with the η phase. This study can be used as reference for heat treatment process design and optimization.

First-principles study on the structure, mechanical and thermodynamic properties of (Ti, Hf, Nb, Ta)C high-entropy carbide ceramics

High-entropy carbide ceramics (HECCs) have demonstrated extraordinary properties and broad application potential. However, the action mechanisms of metallic elements on the properties have not been understood in depth. In this study, the structural stability and the mechanical and thermodynamic properties of (Ti, Hf, Nb, Ta)C HECCs across a broad composition spectrum were systematically analyzed based on the density functional theory and Debye–Grüneisen model. The crystal structure was constructed and validated through experimental testing. The mechanical properties such as elastic moduli, ductility, hardness, and Poisson's and Pugh's ratios were calculated. Furthermore, the temperature dependence of bulk moduli, thermal expansion coefficients, and heat capacities of the HECCs were investigated. To interpret the elastic and toughening mechanisms of non-equiatomic HECCs, the electronic structures were investigated. The results indicate that the HECCs with a single solid solution phase of the FCC rock-salt structure are thermodynamically stable. The HECCs containing higher Nb and Ta contents have greater strength and stiffness, and those containing higher Ti and Hf contents exhibit greater hardness and brittleness than the equiatomic HECC. In addition, non-equiatomic HECCs containing higher Nb and Ta contents have larger bulk moduli and lower linear thermal expansion coefficients, which can be attributed to the stronger covalent interaction among metallic elements and carbon. This study is expected to have an impact on designing ideal HECCs for high-temperature applications under extreme environments.

The role of Ti in the phase transformation and microstructure manipulation of ZrCu alloys with excellent mechanical properties

The effect of Ti content on the phase composition, microstructure manipulation and work-hardening behavior of ZrCu alloys during compression was investigated in this work. The results show that the phase composition, microstructure, mechanical properties and work-hardening ability of ZrCu alloys are very sensitive to Ti content. The introduction of Ti enhances the stability of the austenite phase and the amorphous forming ability of ZrCu alloys. The Zr45Cu50Ti5 alloy exhibited best comprehensive mechanical properties, its yield strength, ultimate compressive strength and fracture strain are 981 MPa, 1922 MPa and 16.9%, respectively. Zr49Cu50Ti1 and Zr47Cu50Ti3 alloys have the best work hardening ability under low strain, and the Zr43Cu50Ti7 alloy has the best work hardening ability under high strain. Finally, the austenite stabilization mechanism, strengthening mechanism and work hardening mechanism are revealed.

Control of Steel Composition and Evolution of Inclusions During Electroslag Remelting of NiCrMoV High‐Strength Steel

Herein, the control of steel composition and evolution of inclusions during the electroslag remelting (ESR) of NiCrMoV high‐strength steel are investigated by laboratory experiments and thermodynamic calculations. The effects of slag systems, atmosphere protection, and surface quality of the consumable electrode are discussed. Results show that slag containing 5% TiO2 and 2% SiO2 is beneficial for controlling Ti and Si losses in steel during the ESR. Using argon gas protection reduces the total oxygen (TO) and nitrogen contents in ESR ingots and improves steel cleanliness, while it has little influence on the types of inclusions. The oxide scales on the electrode surface lead to the reoxidation of liquid steel during the ESR. The TO content increases to 113 ppm and Si, Ti, Als, and Mn contents in ESR ingots are considerably reduced. The inclusions are transformed from Al2O3–CaO–TiOx–MgO to MnO–SiO2–Al2O3–TiOx. Thermodynamic calculations reveal that the decrease in temperature promotes the precipitation of Ca2Ti2O5 and Ca2Ti2O6 in inclusions. As the oxygen content from reoxidation increases, the formation of SiO2 and MnO in inclusions in ESR ingots is promoted. Appropriate process parameters are proposed to control the composition and cleanliness of steel during the ESR.

Achieving optimal Ti content via interfacial reaction layer characteristics of diamond/Cu–Sn–Ti composites

Diamond/Cu–Sn–Ti composites as potential super-hard abrasive products were prepared in this work by spark plasma sintering at 1223 K. The effects of Ti content on the wettability, interfacial reaction layer thickness, and wear resistance of the bulk composite changes were systematically studied. The results revealed that when the Ti content was below 5 wt%, completely uncoated and partially coated diamond grains were still observed, indicating insufficient wettability, and the interfacial reaction layer appeared to be thin. When the Ti content was 5 wt%, all diamond grains were completely coated, and a continuous and stable interfacial reaction layer composed of TiC has been generated, in which the thickness reached a peak value of 1.72 μm. However, when the Ti content exceeded 5 wt%, the formation of brittle Cu41Sn11 phases was observed, which led to inferior wear resistance. The minimum weight loss was obtained at 5 wt% Ti content. Meanwhile, through FIB-TEM, confirmed that the interfacial reaction layer was mainly composed of continuous TiC layer adjacent to diamond and discontinuous TiC layer in the filler metal, and constitute the formation of a high strength metallurgical interfacial bonding layer.

Quartz chemical composition and apatite thermochronology trace leucogranite evolution and thermal history in the Koktokay No. 3 rare metal deposit, Chinese Altai

Koktokay No. 3 pegmatite is a globally renowned rare metal deposit. Recently, rare metal-enriched leucogranite was identified within this deposit. The leucogranite is locally cut by No. 3 pegmatite and scattered as fragments among the pegmatite in some outcrops. In this study, we aimed to investigate the emplacement depth, thermal history, and evolution process of leucogranite based on quartz chemical composition and apatite thermochronology. Li, Al, P, Ge are the higher content elements in leucogranite quartz, and Ti is the lower content element (approximately 38.7, 178, 23.9, 2.7, and 2.0 ppm, respectively). The Al, Ti, and Li contents decreased from the core to the rim of the quartz. The leucogranite quartz compositions have a high Ge/Ti ratio, similar to that of the quartz in the Li-Cs-Ta pegmatites, particularly the Koktokay No. 3 pegmatite. This similarity indicates that the leucogranite was formed by a highly evolved melt. Using laser ablation-inductively coupled plasma-mass spectrometry, the U–Pb age of leucogranite apatite was determined as 189.4 ± 6.8 Ma, which is substantially younger than the previous columbite U–Pb age of No. 3 pegmatite, suggesting that the magmatic-thermal activity of No. 3 pegmatite had interfered with the apatite U–Pb closure system. The apatite low-temperature thermochronology results showed that the thermal history of leucogranite can be divided into two cooling stages: rapid cooling stage (180–155 Ma, 9.6–10.6 ℃/m.y.) and slow cooling stage (from 155 Ma to the present day, 0.8–1.0 ℃/m.y.). According to the thermal history, the exhumation and erosion of the Koktokay No. 3 rare-metal deposit is at least 5–6 km long. Leucogranite formation pressure is approximately 2.5 kbar (1.8–3.7 kbar), and the emplacement depth approximately 9.5 km (7–14 km).

Augmentation of optical and magnetic characteristics at ambient temperature in bismuth ferrite-titanium (BiFe1–xTixO3) multiferroic compounds

A facile sol–gel approach was utilized to synthesis BiFe1-xTixO3 multiferroic ferrites, denoted as BFO-xTi (with x from 0.00 to 0.10). XRD analysis revealed that the undoped BFO ferrite exhibited a rhombohedral structure, and a transition from the rhombohedral phase to the pseudo-cubic phase occurred as the Ti content increased. The optical band gap increased from 2.00 eV to 2.23 eV with a Ti substitution at 0.10 mol. The magnetic properties exhibited a transition from antiferromagnetic to ferromagnetic phase due to the structural phase transition and super-exchange interaction between the 3d orbitals of Ti4+ and Fe3+/Fe2+ at the B-sites through oxygen vacacies. The sample with a 0.10 mol Ti substitution demonstrated the highest M s and M r values of 3.68 emu g−1 and 7.21 × 10–3 emu g−1, respectively. Overall, the results suggest that the BiFe1-xTixO3 multiferroic ferrites with optimal composition hold promise for use in magneto-optical devices.

Microstructure and EMW absorption properties of PDCs-SiCN(Ti) ceramics with adjustable SiC nanowires and TiC nanocrystallines

Herein, a novel type of ceramic material exhibiting tunable electromagnetic properties was synthesized using the polymer-derived ceramics (PDCs) method. The precursor employed in this process was a tetrabutyl titanate-modified polysilazane, which ultimately led to the formation of PDCs-SiCN(Ti) ceramics. High-temperature annealing (1400 °C-1500 °C) was used to prepare PDCs-SiCN(Ti) ceramics, which exhibited a unique dual nanostructure comprising SiC nanowires and TiC nanocrystals and served as effective nanoabsorbents. The SiC and TiC contents are closely related to the annealing temperature and induced Ti content. After annealing at 1500 °C, the PDCs-SiCN(Ti) ceramics with the typical A + B + C electromagnetic absorbing structure exhibited excellent electromagnetic wave (EMW) absorption properties. The PDCs-SiCN(Ti) ceramics, with a Ti content of 5 wt%, demonstrated an effective absorption bandwidth (EAB) of 3.8 GHz, which encompassed 90.5 % of the X band, despite having a relatively thin impedance matching thickness of only 2.1 mm. The outstanding EMW attenuation capability of the PDC-SiCN(Ti) ceramics can be ascribed to their large specific surface area and defects combined with the high permittivity of dispersed TiC nanocrystals, which facilitates multiple reflections of EMW within the SiCN matrix. Therefore, this work provides a controllable preparation method for PDCs-SiCN(Ti) ceramics with various microwave absorbing phases.

Association between trace element contents in normal human breast and age investigated using inductively coupled plasma mass spectrometry

The etiology of breast cancer remains largely unclear; however, it is well known that the incidence of this disease increases with age. In the presented work, for the first time, the age-related changes of Al, As, B, Ba, Bi, Cd, Ce, Cr, Cu, La, Li, Mg, Mn, Nb, Ni, Pb, Rb, Sb, Sn, Sr, Ti, W, and Zn content in the mammary gland of women aged 16-60 years was investigated. For this purpose, a method based on inductively coupled plasma mass spectrometry (ICP-MS) was employed, which makes it possible to determine the mass fractions of these trace elements in microsamples (mass from 10 mg) of breast tissue. With the help of this method, the material obtained during the autopsy of 38 practically healthy women aged 16-60 years who died suddenly was studied. Trace element mass fractions were determined in two age groups of women: 16-40 and 41-60 years old. Using the parametric Student's t-test and the non-parametric Wilcoxon-Mann-Whitney U-test to compare two age groups, as well as Pearson's correlation coefficients between age and trace elements mass fractions, it was found that the Cu, Mg, Rb, and Zn mass fractions in normal breast tissue decrease with age, while the As mass fraction increase. The phenomenon of the age-related changes of trace elements mass fractions in the normal mammary gland, discovered for the first time, requires further detailed study.

Microstructure and fracture toughness of a Nb–Ti–Si-based in-situ composite fabricated by laser-based directed energy deposition

Laser-based directed energy deposition (LDED), a significant integrated preparation technique combining material design and production, has been progressively used to manufacture Nb–Ti–Si-based in-situ composites. However, it is commonly known that Nb–Si-based in-situ composites have low room-temperature fracture toughness. Herein, we have designed a novel Nb–40Ti–10Si–5Al–2V (at.%) composite, the microstructure of LDED-built composite is made up of Nbss and γ-Nb5Si3, the formation of γ-Nb5Si3 precipitate in the Nbss phase with an orientation relationships (ORs) of [1110]γ//[011]Nbss, (10 1‾ 0)γ//(011)Nbss and (1 2‾ 11)γ//(200)Nbss. The composite has Nbss, Nb3Si and γ-Nb5Si3 phases after heat treatment at 1400 °C for 30 h, and δ-Nb11Si4 precipitate has formed in the Nbss phase with an ORs of [100]Nbss//[010]δ, (010)Nbss//(010)δ. The composite processing Nb–40Ti–10Si–5Al–2V (at.%) has outstanding toughness (21.62 MPa·m1/2). It has ascertained that the room-temperature fracture toughness of Nb–Si-based in-situ composite is positively impacted by the high concentration of Ti.

Mechanical properties and wear behaviors of FeCoNiCrMnTix high-entropy alloys manufactured by vacuum arc melting

FeCoNiCrMnTix (x = 0, 2, 4, 6 wt%) high-entropy alloys (HEAs) were prepared using vacuum arc melting. The microstructure, mechanical and wear properties of the HEAs were investigated using XRD, OM, SEM, Vickers hardness, tensile tests and friction tests. The crystal structure of the FeCoNiCrMnTix HEAs consists of FCC and BCC, and the precipitation of the strengthening phase Ni3Ti inhibits the FCC to promote the formation of BCC. The dendrites (DR) of the FCC phase enriched with Fe, Co, and Cr. Ni, Mn, and Ti aggregated between the inter-dendrites (IR) of BCC phase. The addition of Ti to FeCoNiCrMn HEA decreased the grain size. FeCoNiCrMnTi6 reaches a maximum microhardness of approximately 293 HV higher than the equiatomic FeCoNiCrMn HEA (∼151 HV). The significant increase in hardness and wear resistance is attributed to solid solution strengthening, grain refinement, and precipitation hardening. With increasing Ti content, the yield strength of FeCoNiCrMnTix HEAs increased from 296 to 601 MPa and the average coefficient of friction (COF) gradually decreased. Tensile fracture is characterized by ductile and brittle fracture. The generated oxide layer protects the alloy matrix during friction, and the wear mechanism gradually transforms from adhesive wear to abrasive wear.

Ti alloying effects on the microstructure, mechanical properties and damping capacity of Al-Zn eutectoid damping alloys

Four Al-Zn eutectoid damping alloys with nominal compositions of 50Al-(49.9-x) Zn-xTi-0.1Ce (x=0, 0.5, 1 and 2 respectively) (atomic percentages, at%) were prepared by hot extrusion following the resistance and induction melting and homogenization. The effects of Ti content on the microstructure, mechanical properties and damping capacity of Al-Zn eutectoid damping alloys were investigated. The results show that the eutectoid structure in the alloy is refined first and then coarsened with increase in Ti content (1Ti alloy has the finest eutectoid structure), and a small amount of (Al, Zn)3Ti intermetallic blocks are observed in the 2Ti alloy. There exist two types of regions for the eutectoid structures in the four alloys, region Ⅰ has nearly granular morphology and relatively large phase sizes, and region Ⅱ has very fine lamellar structure (the lamellar spacing is only 50–80 nm in 1Ti alloy). With the increase of Ti content, the area percentage of region II exhibits an increasing trend. The tensile property of the alloy is ameliorated by Ti addition, and the tensile strength increases first and then decreases with the increase of Ti content. In particular, 1Ti alloy has a high tensile strength of up to 390 MPa, which is increased by 49.43% compared to that of 0Ti one. The damping capacity of the alloys is improved by proper addition of Ti (tan δ values of 0.5Ti and 1Ti alloys increase by 78.26% and 26.09%, compared to that of 0Ti one), while is not changed obviously by further addition of Ti (up to 2 at%).

Effect of the Ti content and pore size of mesoporous catalysts on CO2 photoreduction

The photocatalytic conversion of CO2 into chemicals and fuels is a promising approach for reducing atmospheric CO2 and addressing energy demands. This study investigates the impact of titanium (Ti) content and pore size in mesoporous silica on CO2 photoreduction (CO2PR) efficiency. Ordered mesoporous silica with a large surface area and stability is used as a matrix for Ti dispersion. Two sets of photocatalysts with varying Ti contents and pore sizes are synthesized and assessed for their microstructures, photoelectric properties, and CO2PR efficiency in both solid–gas and liquid–gas modes. The results reveal that photocatalysts with only 3.0 wt% Ti perform comparably to commercial TiO2 (P25) and can be recycled and reused. Moreover, an enhancement in photocatalytic activity with increasing pore sizes of the photocatalysts is observed. Notably, a photocatalyst with 3.0 wt% Ti and about 8 nm pore size significantly outperforms P25, producing much higher CH4, CO, and CH3OH yields. These findings are crucial for optimizing photocatalyst efficiency and are applicable across various compositions.

Effects of Ti addition and wall thickness on microstructure, hardness, and wear properties of spheroidal graphite cast irons

Spheroidal graphite cast irons (SGCIs) have been commonly used in automotive and energy sectors where superior mechanical strength and wear resistance are required. This paper investigated the performance of the SGCIs under severe wear conditions as a function of Ti content and cooling rate. SGCIs alloyed with various Ti content (0, 0.1, 0.2, 0.3, and 0.5 wt%) were produced by green sand-casting process in different section sizes (10, 30, and 50 mm). Ball-on-disk type wear equipment with an Al2O3 ball was used to determine the wear rates of the SGCI samples. With increasing Ti content, up to 45% of nodular graphite turned into vermicular graphite, depending on the Ti addition and section sizes. Carbide precipitation was observed in the matrix due to the carbide-forming effect of Ti. The hardness and wear resistance of the SGCIs were improved by adding Ti owing to the combined effects of increasing pearlite and TiC particles precipitated in the matrix. Thinner-wall castings provided a faster cooling rate, which improved hardness and wear resistance. Alloying with 0.5 wt% Ti decreased the wear rates up to 35%.

Delineating the significance of sharp boundaries between horizons and their synergetic linkage in calcareous vineyard soils

The present work was undertaken to appraise and delineate the significance of sharp boundaries between horizons in calcareous vineyard soils by evaluating parent material uniformity and pedogenesis. To do so, 10 soil profiles (selected from 275) were investigated. The profiles up to a depth of approximately 150 cm were opened. Macromorphological features were described following FAO guidelines. Physico-chemical properties were analysed by the usual methods. X-ray fluorescence (XRF) was used to determine elemental Ti and Zn concentrations. In terms of the main morphological characteristics, soils are reddish, and have a well-developed solum, a subangular or prismatic structure and friable moist consistency (B horizon) unlike the C horizon, which generally varies from friable to hard or very hard in a massive structure. These latter are usually related to the pedogenesis of evolved soils containing accumulations of calcium carbonate to form calcic or petrocalcic horizons. Other genetic horizons of the studied soils are argillic or cambic, which all lie directly on parent materials, in addition to a surface Ap anthropic horizon. Although the considered soils displayed a significant sharp boundary between some horizons, and even though some soil parent materials were stratified in nature and apparently formed of multidepositional regimes, certainly the vertical distribution of Ti/Zr displayed minor variations with no clear inflection with depth. Therefore, the parent materials of the investigated soils are apparently formed of homogeneous depositional materials. The morphological contrast within a profile is due mainly to pedological processes (they are very mature) rather than to geogenic ones. Nevertheless, the marked contrasts between horizons cannot be explained only by pedogenetic processes, but by other secondary processes related to agricultural use (mechanical impact of tillage). This means a partly artificial distinction that entails surface erosion and, consequently, a manifest redistribution fundamentally on surface horizons. Based on all this, it can be deduced that these soils are formed from local and not from extraregional materials.

Differential intestinal effects of water and foodborne exposures of nano-TiO2 in the mussel Mytilus coruscus under elevated temperature

With the wide use of nanomaterials in daily life, nano-titanium dioxide (nano-TiO2) presents potential ecological risks to marine ecosystems, which can be exacerbated by ocean warming (OW). However, most previous studies have only centered around waterborne exposure, while there is a scarcity of studies concentrating on the impact of trophic transfer exposure on organisms. We investigated the differences in toxic effects of 100 μg/L nano-TiO2 on mussels via two pathways (waterborne and foodborne) under normal (24 °C) and warming (28 °C) conditions. Single nano-TiO2 exposure (waterborne and foodborne) elevated the superoxide dismutase (SOD) and catalase (CAT) activities as well as the content of glutathione (GSH), indicating activated antioxidatant response in the intestine. However, depressed antioxidant enzymes and accumulated peroxide products (LPO and protein carbonyl content, PCC) demonstrated that warming in combination with nano-TiO2 broke the prooxidant-antioxidant homeostasis of mussels. Our findings also indicated that nano-TiO2 and high temperature exhibited adverse impacts on amylase (AMS), trypsin (PS), and trehalase (THL). Additionally, activated immune function (lysozyme) comes at the cost of energy expenditure of protein (decreased protein concentration). The hydrodynamic diameter of nano-TiO2 at 24 °C (1693–2261 nm) was lower than that at 28 °C (2666–3086 nm). Bioaccumulation results (range from 0.022 to 0.432 μg/g) suggested that foodborne induced higher Ti contents in intestine than waterborne. In general, the combined effects of nano-TiO2 and warming demonstrated a more pronounced extent of interactive effects and severe damage to antioxidant, digestive, and immune parameters in mussel intestine. The toxicological impact of nano-TiO2 was intensified through trophic transfer. The toxic effects of nano-TiO2 are non-negligible and can be exerted together through both water- and foodborne exposure routes, which deserves further investigation.

Investigation on microstructures, mechanical properties, and corrosion behavior of novel biodegradable Zn-xCu-xTi alloys after hot rolling fabricated by self-developed newly gradient continuous casting

The poor mechanical properties exhibited by pure Zn effectively prohibit its utilization as a viable material for biodegradable implants. Hence, the primary area of interest has been directed towards alloy design and process strategies of biodegradable Zn alloys. To this end, novel biodegradable Zn-xCu-xTi (Cu: x = 0.001–2.72 and Ti: x = 0.03–1.21) alloys were designed and fabricated using a gradient continuous casting method followed by homogenization and rolling. The fabricated samples were then investigated in terms of their microstructures, mechanical properties, and corrosion behavior. The results showed that the as-cast Zn-0.001Cu-0.037Ti and Zn-1.50Cu-1.06Ti alloys possess better mechanical properties and corrosion resistance. The yield strength, elongation, and highest charge transfer resistance (Rct) of Zn-0.001Cu-0.037Ti were 137 MPa, 60 %, and 2227.9 Ω, respectively. On the other hand, the Zn-1.50Cu-1.06Ti alloy exhibited 250 MPa yield strength, 12.7.% elongation, and 11113.0 Ω Rct, respectively. Higher Cu and Ti content also led to larger second phases. However, as-hot rolled Zn-1.50Cu-1.06Ti alloy displayed better mechanical properties as compared to the Zn-0.001Cu-0.037Ti alloy due to a very fine nanocrystalline structure. Furthermore, the hot-rolled Zn-xCu-xTi alloys demonstrated superior corrosion resistance compared to their as-cast counterparts, as evidenced by the analysis of the potentiodynamic polarization and electrochemical impedance spectroscopy data. This improved corrosion resistance is attributed to the refined grain size, fractured second phases which reduce both the anode and cathode areas, and the formation of protective oxide layers. Lastly, the corrosion products primarily consisted of carbon, phosphorus, calcium, and oxygen, suggesting the presence of Zn(OH)2, carbonates, and phosphates.