Corrosion Resistance Of Titanium Alloys Research Articles

Corrosion behavior of novel Ti6422 alloy with equiaxed structure and lamellar structure in HCl solution

This study systematically investigated the electrochemical corrosion and static immersion corrosion behavior of the novel Ti6422 (Ti-6Al-4V-2Mo-2Fe) alloy with equiaxed (EM) and lamellar structure (LM) in HCl solution. The differences in corrosion performance between EM and LM samples were analyzed based on the characteristics of the passive film and substrate microstructure. Results indicated that the LM sample contained higher contents of TiO₂, Al₂O₃, and MoO₃ with higher stability compared with the EM sample, and the thickness of passive film was approximately twice that of the EM sample. Additionally, the donor density of LM sample was lower than EM sample. These findings indicate that the passive film on LM samples is thicker, with fewer defects and higher density. Electrochemical corrosion results revealed that the corrosion current of LM samples was lower and the polarization resistance was higher than these of EM samples, both suggesting superior corrosion resistance of LM samples. Immersion corrosion further confirmed that the LM sample had a lower corrosion rate. The enhanced corrosion resistance in LM samples was primarily due to higher content of corrosion-resistant β phase. Conversely, the numerous micro-galvanic cells between αs precipitates and adjacent β phase in EM samples weakened the corrosion resistance. Overall, these results demonstrated that regulating microstructure through heat treatment is an effective strategy for improving corrosion resistance of titanium alloys.

Enhancing Corrosion Resistance of Titanium Alloys via Hydrothermal Etching: Nanostructure Formation under Varied Temperature Conditions

Enhancing Corrosion Resistance of Titanium Alloys via Hydrothermal Etching: Nanostructure Formation under Varied Temperature Conditions

Shot peening pre-treatment for nano-nitriding layer formation to enhance wear and corrosion resistance in medical titanium alloys

Due to its exceptional biocompatibility, Ti6Al4V finds extensive application in the medical field, particularly in joint replacement and orthopedic surgery. To augment the wear and corrosion resistance of the titanium alloy in physiological environments, SP and PN treatments were applied. This study systematically explores the synergistic impact of SP on PN of titanium alloy through microhardness testing, micromorphology observation, microstructure characterization, as well as wear and electrochemical experiments. The findings reveal that SP refines surface grains, facilitating PN and leading to the formation of a thicker nitride layer on titanium alloy surfaces. Compared to the initial titanium alloy, surface microhardness increases by 51.4 %, and the wear rate experiences a two-order-of-magnitude reduction. Moreover, the SP-PN treatment enhances the electrochemical corrosion resistance of titanium alloys, underscoring its effectiveness in improving the wear and corrosion properties of medical titanium alloys.

Corrosion resistance of diamond films with different grain sizes

Titanium alloys are widely used in the aerospace industry due to their excellent comprehensive properties. However, as the application becomes more and more extensive, higher requirements are put forward for the corrosion resistance of titanium alloys. Due to its natural chemical stability, diamond has become a good corrosion-resistant material. Diamond films with three different grain sizes were prepared on the surface of titanium alloy by hot-filament chemical vapor deposition (HFCVD). The protective efficiency of the three kinds of films to the substrate is above 90 %. The corrosion resistance of the nanocrystalline diamond (NCD) films is obviously better than that of the microcrystalline diamond (MCD) films. For NCD films, as the diamond grain size decreases, a cluster structure of particle stacking is formed, which hinders the arrival of corrosive substances to the substrate and further improves the corrosion resistance.

Electrochemical characteristic and microstructure of Ti-6Al-7Nb alloy by centrifugal casting for orthopedic implant based on ageing time variations

The alternative Ti-6Al-7Nb alloy has gained extensive progression due to its ability to eliminate the cytotoxicity of vanadium (V) in Ti-6Al-4V alloy for orthopedic implants. The production of titanium alloys by centrifugal casting shows significant potential to reduce costs. Heat treatment and aging can tailor the microstructure and improve the corrosion resistance of titanium alloys. This study examines the effects of various ageing times on the microstructure and corrosion resistance of a centrifugal cast Ti-6Al-7Nb alloy that has previously been heated and treated at a temperature of 1050 °C, and subsequently cooled to room temperature in argon atmosphere gas. Ageing was carried out at a temperature of 550 °C with variable times of 0, 4, 6, and 8 hours. The surface morphology, metal phase changes, and electrochemical characterization were tested using an optical microscope (OM), X-ray diffraction (XRD), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The basket-weave microstructure is formed where globularization occurs in some phases as ageing time increases. Increasing the FWHM α value is correlated with increasing the amount of α' martensite phase. As an ageing time enhances, the temperature might offer a greater driving constrain for the nucleation and expansion of the lamellar phase (α). Ageing of 8 hours has the lowest corrosion rate, 0.0023 mpy and highest corrosion resistance, 90457 Ω∙cm2, due to the partially bimodal structure and grain refinement with a smallest grain size of 327.87 µm. Tafel polarization results show that all passivated samples are stable in the Solution Body Fluid (SBF). This work can be used as a starting point for developing microstructural evolution in titanium alloys

Use of a natural rock material as a precursor to inhibit corrosion of Ti alloy in an aggressive phosphoric acid medium

The mechanism of interaction between magnesite mineral and phosphoric acid (0.001–0.5 M) in addition to the determination of the protective properties for Ti alloy (working electrode) in phosphoric acid both with and without an inhibitor have been investigated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. Results of electrochemical tests show that the corrosion resistance of titanium alloy in phosphoric acid solution only increased and hydrogen production decreased by either decreasing acid concentration or increasing immersion time associated with the thickening of the oxide film formed on the alloy surface. On adding magnesite, the corrosion resistance of Ti alloy is enhanced by increasing the phosphoric acid concentration (0.001–0.5 M) due to the formation of sparingly soluble magnesium phosphate film on the alloy surface that inhibits the effect of increasing hydrogen evolution reaction due to the pH value decreases. The increasing adsorption behavior of the magnesite inhibitor and decreasing its diffusion were deduced from EIS measurements. Thus, the addition of 3% magnesite minimizes the corrosion by forming a new protective film (Mg3(PO4)2), which differs from the traditional passive film and prevents the effect of the increase of hydrogen evolution. The surface morphology and chemical composition of the tested alloy were determined using scanning electron microscopy (SEM), Fourier transform Infra-Red spectroscopy (FTIR), X-ray diffraction (XRD), X-ray Fluorescence (XRF) and In situ Raman spectroscopy.

Exploring the impact of Al alloying on microstructure and hot nitric acid corrosion resistance of Ti-xAl (x=0, 1, 2, 3, 4, 5) alloys

Enhancing the corrosion resistance of titanium alloys in hot nitric acid environments is imperative for advancing spent fuel reprocessing. Here, we explored the impact of Al alloying on microstructure and corrosion resistance of Ti-Al alloys via experimental assessments and theoretical computations. Results indicated that Al alloying induced a comparable Widmanstatten structure and increased hardness. Electrochemical findings demonstrated the optimal corrosion resistance for the alloy with 4 wt% Al. DFT computation presented the highest WF and the lowest EF for Ti-4Al alloy, indicative of superior thermodynamic stability. Eventually, a mechanistic understanding of Al alloying on nitric acid corrosion resistance was proposed.

The Study on Corrosion Resistance of Ti-6Al-4V ELI Alloy with Varying Surface Roughness in Hydrofluoric Acid Solution

The corrosion resistance of titanium alloy poses a crucial challenge, significantly affecting its prospect for service and application. The present study aimed to investigate the corrosion resistance of Ti-6Al-4V ELI alloys with varying surface roughness in hydrofluoric acid solution, in order to assess the influence of roughness on their corrosion resistance performance. The weight loss percentage, surface morphology evolution, and roughness variation of Ti-6Al-4V ELI alloys before and after exposure to hydrofluoric acid corrosion were characterized. While the weight loss and weight loss percentage of the Ti-6Al-4V ELI alloy increased with prolonged corrosion, the overall weight loss rate decreased. The accumulation of TiF3 phases and depletion of the Ti-6Al-4V ELI matrix mutually led to the alterations of the surface roughness. Due to the inability to prevent fluoride ions from contacting with the Ti-6Al-4V ELI alloy, continuous corrosion occurred in hydrofluoric acid. Based on these experimental results and analysis, the corrosion mechanism of the Ti-6Al-4V ELI alloy corroded by hydrofluoric acid solution was elucidated. Furthermore, an analysis was conducted to explore the influence of corrosion time on mechanical properties by analyzing the decay in compressive properties of the Ti-6Al-4V ELI titanium alloy after hydrofluoric acid corrosion treatment. The bearing capacity of the Ti-6Al-4V ELI alloy deteriorated over the corrosion time.

Mechanical properties and corrosion behavior of electron beam cold hearth melting high strength and high corrosion resistant Ti-0.3Mo-0.8Ni alloy with different states

In this study, a large size Ti-0.3Mo-0.8Ni (TA10) alloy ingot melted by electron beam cold hearth melting (EBCHM) technology was investigated. The microstructure, mechanical properties, and corrosion behavior of as-cast, hot-rolled, and annealed TA10 alloys were investigated. The results show that different states of TA10 alloys have different microstructure and properties. The microstructure of the as-cast TA10 alloy exhibits the Widmanstätten α phase, and the hot-rolled TA10 sheet shows a fibrous structure with an obvious rolling streamline. After 650 °C annealing, the intergranular β phase decreases, and most of the strip α phase changes to the equiaxed α phase. With the annealing temperature increasing to 840 °C, the microstructure gradually changed from an equiaxed structure to a duplex structure. The mechanical properties of the TA10 alloy were enhanced after hot-rolling with an increase in ultimate tensile strength from 386.5 MPa to 610 MPa. Additionally, the elongation increased from 15.6 % to 23.3 %. Upon annealing at varying temperatures, it was observed that the strength decreased, reaching to 423.5 MPa at 650 °C and 478.2 MPa at 840 °C, while the plasticity increased significantly, reaching to 26.5 % at 650 °C and 28.6 % at 840 °C. The improved strength was attributed to the better grain boundary slip of the equiaxed structure. The corrosion resistance of titanium alloys is closely connected with their microstructure. The results of the immersion corrosion test indicate that the samples in various states exhibit similar corrosion behavior. Additionally, the hot-rolled TA10 alloy shows the highest corrosion resistance, with a lower corrosion rate of 0.34459 mm/year. The as-cast TA10 alloy shows the lowest corrosion resistance, with a lower corrosion rate of 1.37559 mm/year.

Enhancing PEO coating on TC6 alloy through in-situ synthesis of MoSe2—Towards more efficient wear-reducing lubrication and wear resistance

Plasma electrolytic oxidation (PEO) has demonstrated significant enhancements in the mechanical properties and corrosion resistance of titanium alloys. Despite these advantages, the presence of micropores and microcracks in the coating can still detrimentally impact tribological properties. This paper introduces a novel approach involving the in-situ growth of a surface structure. The resulting interface structure exhibits outstanding tribological properties under a load of 3 N and a speed of 1.5 cm/s. In contrast to prior studies, improvements are made to the electrical parameters and electrolyte formula of Plasma electrolytic oxidation, facilitating the in-situ growth of MoSe2. This results in the formation of a lubricating layer and a robust TiO2 ceramic coating with excellent adhesion. A systematic analysis of friction, wear characteristics, reveals that MoSe2 in situ grow on the surface of the PEO coating, within micropores, microcracks, and crater structures after hydrothermal treatment. This process significantly enhances the microporous structure of the coating, with the MoSe2 film forming a dense and uniform interlocking layer with the PEO lower layer. Dry friction test experiments demonstrate a 33.7% reduction in friction coefficient and a 29% decrease in wear rate compared to the PEO sample, indicating the synergistic effect between the MoSe2 film and the PEO coating.

Thermal-Mechanical Effect and Removal Mechanism of Ti-6Al-4V During Laser-Assisted Grinding

The low density and high corrosion resistance of titanium alloy make it a material with various applications in the aerospace industry. However, because of its high specific strength and poor thermal conductivity, there are problems such as high cutting force, poor surface integrity, and high cutting temperature during conventional machining. As an advanced processing method with high efficiency and low damage, laser-assisted machining can improve the machinability of titanium alloy. In this study, a picosecond pulse laser-assisted scratching (PPLAS) method considering both the temperature-dependent material properties and ultrashort pulse laser’s characteristics is first proposed. Then, the effects of laser power, scratching depth, and scratching speed on the distribution of stress and temperature field are investigated by simulation. Next, PPLAS experiments are conducted to verify the correctness of the simulation and reveal the removal behavior at various combinations of laser power and scratching depths. Finally, combined with simulated and experimental results, the removal mechanism under the two machining methods is illustrated. Compared with conventional scratching (CS), the tangential grinding force is reduced by more than 60% and the material removal degree is up to 0.948 during PPLAS, while the material removal is still primarily in the form of plastic removal. Grinding debris in CS takes the form of stacked flakes with a “fish scale” surface, whereas it takes the form of broken serrations in PPLAS. This research can provide important guidance for titanium alloy grinding with high surface quality and low surface damage.

Effect of Repeated Processing Passes during Ultrasonic Rolling on Fatigue Performance and Corrosion Resistance of Ti6Al4V Alloy

Ultrasonic surface rolling processing (USRP) is a new method to improve the fatigue performance of titanium alloy, and repeated processing pass is an important factor that affects its strengthening effect. The effect of USRP passes on the surface microstructure, residual stress, fatigue performance and corrosion resistance of titanium alloy is researched via SEM, X-ray diffractometer, rotating–bending fatigue test and electrochemical impedance spectroscopy. The results show that Ti6Al4V alloy undergoes cumulative plastic deformation during USRP process, the surface grains are refined and a residual compressive stress field with a thickness of 500 μm is introduced, which together improve the fatigue performance of the Ti6Al4V alloy. Increasing the repeated processing passes will deepen the grain refinement layer and increase the surface hardening effect, but the fatigue life of the Ti6Al4V alloy does not increase with an increase in processing passes. A five-passes processing under a static force of 550 N can result in a greater gain for the fatigue resistance of the Ti6Al4V alloy; the fatigue life of a five-passes-processed sample under 600 MPa is 8 times higher than that of an untreated sample, and its fatigue crack source initiates at the subsurface away from the surface of 180 μm. Furthermore, Ti6Al4V alloys treated by USRP show a better corrosion resistance in both neutral and acidic solutions, especially for the five-passes-processed sample.

Phase Composition, Microstructure, Surface Hardness, and Corrosion Resistance of Surface Plasma Gas Nitrided Titanium Alloy Ti-10V-2Fe-3Al with Indirect Plasmatron

This study investigates and analyzes the influence of plasma gas nitriding with indirect plasmatron on the phase transformations, microstructure, surface microhardness, and corrosion resistance of titanium alloy Ti-10V-2Fe-3Al. In order to achieve this, the limits of the power used in this process are a minimum of 12 kW and a maximum of 35 kW. The thermochemical treatment time intervals are set at 5, 10, and 15 min. It is found that the phase composition of the surface layer after plasma gas nitriding consists of α-Ti, (N, O), TiN, and TiO2. Titanium oxides are detected only on the outermost surface of the nitrided layers. The measured hardness of the plasma gas nitrided layers obtained of Ti-10V-2Fe-3Al is up to 650 HK0.05. Potentiodynamic polarization analysis indicates that the subjects nitrided using 18 kW of power for 15 min have the lowest corrosion rate, while the highest corrosion rate is observed in those nitrided at 25 kW for 15 min.

NaCl-induced hot-corrosion behavior and mechanism of TiSiCN/Ag nanocomposite coatings by arc ion plating

TiSiCN/Ag nanocomposite coatings were deposited on the surface of titanium alloys by multi-arc ion plating. Under thermal-salt coupling, the coatings' hot corrosion behavior was studied. The corrosion resistance of titanium alloys can be greatly enhanced by the TiSiCN/Ag nanocomposite coatings. The reason is that the introduction of Ag can prevent the growth of columnar crystals and obtain a dense nanocomposite coating, thus reducing the invasion channels of Cl- and O2. Secondly, Ag can efficiently bind Cl- and prevent its diffusion, protecting the coating and titanium substrate from Cl- damage.

Low-cycle fatigue behaviour of hot-rolled titanium-clad bimetallic steel

Titanium-clad (TC) bimetallic steel is able to integrate the superior corrosion resistance of titanium alloy into traditional corrosion-susceptible structural steels, producing prominent life-cycle safety, serviceability and durability. Nevertheless, the relevant seismic performance and fatigue behaviour reported in existing literature are still limited and insufficient to support the codification for structural design of such advanced steel. In order to develop proper plastic/seismic design methodology for TC bimetallic steel structure, the cyclic behaviours and low-cycle fatigue life prediction of such metal must be thoroughly investigated. This paper aims to study the low-cycle fatigue behaviour of hot-rolled bonded TC bimetallic steel manufactured from TA2 titanium alloy and Q355B structural steel. The strain amplitude of low-cycle fatigue (LCF) test ranges from 0.5% to 2.5%, and the strain ratio applied herein includes 0 and -1. The experimental phenomenon, LCF failure mechanism, cyclic stress-strain relationship of different tests are thoroughly compared and discussed. Besides, the influence of strain rate and bond strength are simultaneously demonstrated. The LCF life are fitted and validated through Basquin-Coffin-Manson model, Kuroda model and energy method, respectively. The research outcomes demonstrate that the LCF cracks of TC bimetallic steel tend to be initiated at the cladding layer and propagated into the substrate layer due to a coupled buckling-fatigue failure mechanism. Several representative fatigue behaviour of conventional mild (CM) steels including the three-stage cyclic softening and mean stress relaxation have not been observed in this experimental study. The strain rate exhibits distinct influence on the LCF life and failure mechanism. Both Basquin-Coffin-Manson model and energy method can provide more favourable prediction accuracy for LCF life of TC bimetallic steel than the Kuroda model. Generally the LCF life of TC bimetallic steel is shorter than that of structural steels, stainless steels, titanium alloys and stainless-clad (SC) bimetallic steels. The test records and fatigue-life model parameters obtained can lay a solid foundation for seismic analysis and damage evaluation of TC bimetallic steel structure.

Surface Characterization of New β Ti-25Ta-Zr-Nb Alloys Modified by Micro-Arc Oxidation.

The technique of surface modification using electrolytic oxidation, called micro-arc oxidation (MAO), has been used in altering the surface properties of titanium alloys for biomedical purposes, enhancing their characteristics as an implant (biocompatibility, corrosion, and wear resistance). The layer formed by the micro-arc oxidation process induces the formation of ceramic oxides, which can improve the corrosion resistance of titanium alloys from the elements in the substrate, enabling the incorporation of bioactive components such as calcium, phosphorus, and magnesium. This study aims to modify the surfaces of Ti-25Ta-10Zr-15Nb (TTZN1) and Ti-25Ta-20Zr-30Nb (TTZN2) alloys via micro-arc oxidation incorporating Ca, P, and Mg elements. The chemical composition results indicated that the MAO treatment was effective in incorporating the elements Ca (9.5 ± 0.4 %atm), P (5.7 ± 0.1 %atm), and Mg (1.1 ± 0.1 %atm), as well as the oxidized layer formed by micropores that increases the surface roughness (1160 nm for the MAO layer of TTZN1, 585 nm for the substrate of TTZN1, 1428 nm for the MAO layer of TTZN2, and 661 nm for the substrate of TTZN2). Regarding the phases formed, the films are amorphous, with low crystallinity (4 and 25% for TTZN2 and TTZN1, respectively). Small amounts of anatase, zirconia, and calcium carbonate were detected in the Ti-25Ta-10Zr-15Nb alloy.

Role of Ta in improving corrosion resistance of titanium alloys under highly reducing condition

Great improvement on corrosion resistance was achieved by adding small amount of Ta into ASTM Gr13 titanium alloy. Main contribution to the improved corrosion resistance originated from the stabilized passive film in terms of the prolonged time to passivity loss. OCP results showed that the OCP transition from the passive state to corroding one prolonged with the Ta content. This behavior was also supported by EIS results, where the loop shrinkage denoting the passivity loss was retarded and/or inhibited by the Ta addition. Microstructural analysis revealed that the added Ta functioned as both substitution element and solid solution one, leading to the growth of the precipitates including β-Ti phase and formation of the complex structured passive film. Especially, the prominent stability of the passive film observed for Gr13–1.0% Ta was ascribed to the high content of the Ta oxide in the passive film, meaning that the complex oxide film required the minimum amount of the Ta oxide to obtain the excellent stability of the passive film against the high concentrated acid solution.

Investigation of Structure and Corrosion Resistance of Titanium Alloys Produced by the Method of Spark Plasma Sintering

Investigation of Structure and Corrosion Resistance of Titanium Alloys Produced by the Method of Spark Plasma Sintering

Experimental Analysis of Superplastic Deformation of Titanium Alloy Based on Sports Equipment

At present, titanium alloy is widely used in the field of materials. Because of its high specific strength and good corrosion resistance, it is also widely used in sports equipment. To overcome the shortcomings of traditional sports equipment, such as low yield and weak strength, the superplastic deformation effect of titanium alloy was tested and analyzed in this paper. The superplastic strength of titanium alloy was adjusted by adjusting the structure of the material. In this paper, by adjusting the proportion of Ti, Mo, alloy, CD, and Fe, the inductively coupled parameters of sports equipment were improved by vacuum consumable melting. The macro high temperature tensile test of sports equipment was carried out, and the temperature and strain rate under different states were recorded. Finally, the mechanism of superplastic deformation of titanium alloy for sports equipment is analyzed. The results show that the superplastic titanium alloy has higher elongation after fracture at high temperature and lower strain rate. The elongation ratio is more than 90% between 500 °C and 800 °C. At high temperature, the corrosion resistance of titanium alloy is high α, The number of phases decreases, and the alloy particles change from short rod to equiaxed. When the strain rate is reduced, the mechanical properties of titanium alloy are improved α, phase increases, the β the number of phases decreased. From its mechanism, the elongation of titanium alloy is caused by the dislocation movement caused by its structure. Therefore, titanium alloy in sports equipment can generally increase the short axis shape to improve the superplasticity of titanium alloy.

Effects of different annealing cooling methods on the microstructure and properties of TA10 titanium alloys

The microstructure, mechanical properties, and corrosion resistance of TA10 titanium alloy annealed via different cooling methods were investigated. After annealing, the intergranular β phase decreases, and most of the strip α phase changes to the equiaxed α phase. The grain size of the equiaxed α phase is the largest, and the content of the primary α phase is the lowest at the longest annealing cooling time. The TA10 titanium alloy sheet with furnace cooling shows better plasticity than that with air cooling. The tensile strength and Vickers hardness gradually decrease with increasing furnace cooling time, and the elongation increases Different annealing cooling methods result in the same corrosion behavior, but the corrosion resistance is different. The sample with the longest cooling time has the highest corrosion resistance. Prolonging the cooling time after annealing is helpful to improve the corrosion resistance of titanium alloy.