Commercial Pure Titanium Research Articles

Combined severe plastic deformation processing of commercial purity titanium enables superior fatigue resistance for next generation implants

Commercial purity titanium (cp-Ti) is considered for replacing Ti64 as an implant material in various applications, due to the potential toxicity associated with the release of Al and V ions. However, the mechanical properties of cp-Ti, particularly fatigue resistance, are inadequate for this purpose. In this study, cp-Ti grade 4 rods were processed using a combination of equal channel angular pressing and rotary swaging (ECAP/RS). Tensile and fatigue tests were conducted, along with detailed microscopy and evaluation of corrosion resistance and biocompatibility. An average yield strength of 1383 MPa was obtained while maintaining moderate ductility of 10 %. This represents the highest strength ever recorded for cp-Ti, even exceeding that of Ti64. Additionally, fatigue endurance limit increased by 43 % up to 600 MPa, almost obtaining that of Ti64. Strengthening mechanisms were attributed to the ultrafine-grained (UFG) microstructure generated by ECAP/RS, along with strong crystallographic texture and formation of sub-grain structure. Furthermore, the corrosion resistance and biocompatibility of cp-Ti were largely unaffected, potentially easing regulatory transition in future medical devices. Thus, these results demonstrate high potential of combined ECAP/RS processing to manufacture UFG cp-Ti grade 4 materials that prospectively allow for the substitution of questionable alloys and downsizing of medical implants.

Wettability and adhesion of nanotubes applied to the surface of titanium implants by anodic oxidation.

The aim of this study was to evaluate the wettability and adhesion of self-organized TiO2 nanotubes formed on the surface of 8 commercially pure titanium (CP-Ti) disks and 12 dental implants (n = 12) by anodization in a glycerol-H2O (50-50 v/v) electrolyte containing NH4F. Two disk specimens were not submitted to anodization (controls). The nanotubes thus obtained had average dimensions of 50 nm in diameter by 900 nm in length. The treated disk specimens were stored for 2, 14 and 35 days (n = 2), and the wettability of their surfaces was evaluated with a goniometer at the end of each storing period. The adhesion of nanotubes to titanium was evaluated by field emission scanning electron microscopy after subjecting the 12 implants to a simulation of clinical stress in two-part synthetic bone blocks. After installing the implants with the application of an insertion torque, the two halves of the block were separated, and the implants were removed. The nanotubes remained adhered to the substrate, with no apparent deformation. The contact angles after 14 days and 35 days were 16.47° and 17.97°, respectively, values significantly higher than that observed at 2 days, which was 9.24° (p < 0.05). It was concluded that the method of anodic oxidation tested promoted the formation of a surface suitable for clinical use, containing nanotubes with levels of wettability and adhesion to titanium compatible with those obtained by other methods found in the literature. The wettability, however, did not prove stable over the tested storage periods.

A comparative analysis of predictive models for estimating the formability of stamped titanium bipolar plates for proton exchange membrane fuel cells

The microchannels on the bipolar plates (BPPs) of a proton exchange membrane fuel cell (PEMFC) have various functions. Increasing the microchannel depth leads to an increase in the efficiency of the fuel cell. In this paper, metallic BPPs of the PEMFC made of commercial pure titanium (CP-Ti) with an initial thickness of 0.1 mm are manufactured using the stamping process. First, after performing the process using experimental tests and finite elements (FE) simulation, the accuracy of the numerical results is confirmed. In the following, using the FE model and considering process parameters including die clearance, forming speed, and sheet/die friction coefficient, a set of experiments is implemented using the response surface method (RSM). The results of the filling rate are obtained from the experiments and a regression model is established to predict the filling rate of the microchannel. Then, four meta-heuristics methods including artificial bee colony optimization (ABCO), genetic algorithm (GA), artificial neural network (ANN), and adaptive neuro-fuzzy inference system (ANFIS) are used to estimate the formability of the CP-Ti BPPs. According to the results, the ANFIS model with an error of 0.0062 × 10−3 % compared to experiments is more reliable to predict the filling rate in the stamping of the CP-Ti BPPs.

Effect of pre-deformation on hydrogen diffusion and hydrogen induced damage in commercially pure titanium

This work aims to elucidate the interaction between hydrogen atoms and pre-introduced dislocations in commercially pure titanium (CP-Ti). Positron annihilation spectroscopy supplemented by the first-principle calculations was utilized to reveal the effects of dislocation densities on the formation of hydride types and the concentration of hydrogen-induced defects in CP-Ti. Results show that, in the hydrogen-charged sample with 40 % deformation, hydrogen-induced damage gradually decreases when the hydrogen enters the sample at a depth of about 350 nm. This finding suggests that the high-density dislocations present in deformed specimens effectively trap hydrogen atoms and inhibit their diffusion, which ultimately mitigate damage within the samples. γ-TiH and δ-TiH2 hydrides are observed in the hydrogen-charged sample. The thermal desorption spectroscopy results show that the desorption amount of deuterium decreases from 1.14 × 1018 D/cm2 to 5.10 × 1017 D/cm2 with an increase in dislocation density because dislocations inhibit the diffusion of deuterium. In samples with higher deformation, the high dislocation density inhibits the formation of δ-TiH2 hydrides and promotes the formation of γ-TiH hydrides, which significantly reduce the hardening of samples. These results provide insight into the interaction of hydrogen with pre-introduced defects and provide strong theoretical support for the development and improvement of more damage-resistant materials.

Residual stress, fatigue behavior, and mechanical properties of equal-channel angular pressed commercial pure titanium

Residual stresses, fatigue behavior, and mechanical properties of equal channel angular pressing (ECAP) commercial pure titanium (CP–Ti) are investigated in this study. Residual stresses can significantly affect the performance and reliability of CP-Ti components under cyclic loading conditions. The study focuses on understanding the relationship between ECAP processing, residual stresses, and fatigue behavior in CP-Ti. The ECAP process was employed to produce CP-Ti grade 2 samples, and their fatigue behavior was characterized. The results revealed a significant increment in residual stresses, fatigue strength, microhardness, and tensile strength by ECAP processing on the CP-Ti. The measured fatigue limit of the processed CP-Ti was found to be higher than that of coarse-grained CP-Ti and approaches the fatigue limit of the Ti–6Al–4V alloy. Residual stresses resulting from non-conventional machining processes and surface treatments are known to affect the fatigue life of titanium alloys. Compressive residual stresses have been shown to inhibit the growth rate of fatigue cracks and improve fatigue life. Understanding the effect of residual stresses on the fatigue behavior and mechanical properties of ECAP-processed CP-Ti is crucial to optimizing the design and ensuring the long-term durability of CP-Ti components in engineering applications.

Wear mechanism transforming of ultrafine-grained pure titanium by multi-axial forging and low-temperature annealing

The effect of microstructure and mechanical properties of submicro grained commercial pure titanium (CP–Ti) on the wear mechanism is still unclear. In the present work, CP-Ti samples were subjected to multi-axial forging (MAF) and low-temperature annealing treatment to prepare ultrafine-grained (UFG) material. The mechanical properties, microstructure, and tribological characterization between coarse-grained (CG) sample and UFG samples were comparatively studied. The results showed that the MAF sample could reach a grain size of 165 nm, while its grains coarsened slightly after low-temperature annealing. The MAF sample had the highest strength and hardness and the lowest coefficient of friction, but only a 7.3 % decrease in wear rate compared to the CG sample. The 400 °C annealed MAF sample possessed a good combination of tensile strength (814 MPa) and elongation (18.6 %), resulting in the lowest wear rate of 16.8 × 10−5mm3/(N∙m). The dominated wear mechanisms of the CG sample, MAF sample and 500 °C annealed MAF sample were abrasive wear, adhesive wear and delamination wear, while the primary mechanism of the 400 °C annealed MAF sample was abrasive wear and adhesive wear. It was found that the wear mechanism transforming, higher hardness and sufficient work hardening could be responsible for lower wear rate of the 400 °C annealed MAF sample. The 400 °C annealed MAF sample showed a thinner and more homogeneous deformation layer near the worn surface, and its thickness of deformation layer was about 8 μm.

Analysis of Microstructure, Texture Evolution, and the Mechanism of Grain Refinement of Commercially Pure Titanium During Cold Rolling: Experiment and Simulation

A comprehensive understanding of the microstructures and texture evolutions during the rolling process is of great significance for the preparations of high‐quality commercially pure titanium (CP‐Ti) sheets. Therefore, in the present work, the effects of rolling reductions on the microstructures and textures of CP‐Ti are investigated by optical microscope, electron backscatter diffraction, and X‐ray diffraction. A crystal plasticity finite element model (CPFEM) is developed to accurately predict the rolling deformation behaviors of CP‐Ti sheets. The results show that the slip and twinning including , compression twins and extension twins are prone to plastic deformations during the whole rolling process. The c‐axes of grains gradually tilt toward the transverse direction and the grains gradually deviate from the original //rolling direction (RD) to //RD. As a result, the mixed textures of and are developed in the specimen. The grain refinements are closely linked with the developments of and twins. In addition, the twin fractions and texture evolutions are well predicted by the CPFEM model. These results documented in this work should not only help to elucidate the microstructures and texture evolutions of CP‐Ti, but also shed important light on improving its properties.

Investigation on the performance of Pt surface modified Ti bipolar plates in proton exchange membrane water electrolyzer

This study comprehensively investigates the electrochemical and passive behaviors of Pt-coated commercially pure titanium (CP-Ti), with a specific focus on the influence of preparation power. The research highlights a positive correlation between coating grain size and the preparation power. Furthermore, the Pt coating proves effective in impeding CP-Ti passivation and exhibits a weak influence on the energy barrier height with changing electrode potential. Among different power levels, the coating prepared at 300 W exhibits the highest corrosion resistance, as evidenced by the maximum Rct value of 8.971 × 104 Ω cm2. The predominance of metallic Pt accounts for minimal variation in interfacial contact resistances. Moreover, Pt coating effectively reduces cell resistance and protects bipolar plates, though it falls short in effectively alleviating the degradation.

Evaluation of Adhesion for Better Electrodeposited Cu Foil on Titanium Substrate

Titanium metal is known to have good corrosion resistance. For the plating of Cu in many industrial applications, Ti metal is commonly used as the cathode for the reduction of Cu. Under an acidic and high temperature environment, the passivation layer on the surface of the titanium metal tends to react with acidic solution. As a result, the corrosion of the active titanium metal was observed. In this study, the corrosion behavior of commercial pure titanium in acid copper sulfate baths was investigated, and several surface treatments were used to improve the corrosion resistance of titanium passive layer. The microstructure of titanium metal after immersion in acid copper sulfate solution was examined by using SEM and FIB. The pitting corrosion of Ti was clearly observed using SEM. The corrosion mechanism of the titanium metal in the sulfuric acid solution was discussed. In addition, the electrochemical characteristics of commercial pure titanium metal in sulfuric acid solution were also analyzed using the three-pole potential measurement method.

Enhancing Oxygen Evolution Reaction Performance: Electrochemical Activation of the Biphasic CoNi/Zn(Fe,Al,Cr)2O4 via Controlled Aluminum Leaching Facilitated Surface Reconstruction

AbstractGiven that the oxygen evolution reaction (OER) faces challenges due to its sluggish kinetics, development of efficient and robust OER catalytic electrodes is critical for reducing the cost of hydrogen production through electrochemical water splitting. In this study, a biphasic CoNi/Zn(Fe,Al,Cr)2O4 coating, characterized by a densely organized stalagmite‐like microarray structure, is deposited on a commercial pure titanium plate, creating an exceptionally effective OER catalytic electrode. The formation of numerous metal/spinel oxide heterogeneous interfaces is demonstrated to enhance its electron transfer ability and conductivity. At high potentials, aluminum leaching and lattice oxygen consumption can facilitate deep surface reconstruction of highly active Fe‐doped CoNiOOH phase inducing electrochemical activation, further optimizing thermodynamic barrier of the fundamental reaction step. Ultimately, this electrode showcases exceptional OER catalytic performance (low overpotential of 248 and 335 mV to deliver the current density of 10 and 100 mA cm−2) compared to commercial IrO2 catalyst (overpotential of ≈310 mV at 10 mA cm−2). Moreover, it demonstrates high current stability sustaining a current density of 500 mA cm−2 for 100 h. This work deepens the comprehension of the surface reconstruction process in OER and, more broadly, introduces a new avenue for designing and enhancing the performance of catalytic materials.

Photoactive TiO2 ceramic coatings obtained by laser-assisted plasma electrolytic oxidation on commercial pure titanium

To address the challenges of controlling the morphology and crystalline phase composition of photoactive TiO2 ceramic coatings produced by existing plasma electrolytic oxidation (PEO) technology, a novel laser-assisted PEO method is proposed in this study. The analysis has revealed that the TiO2 coatings prepared by the laser-assisted PEO method had a more intricate 3D multi-porosity architecture. Furthermore, the ratio of TiO2 crystalline phases (anatase to rutile) in the coating can be controlled by adjusting the laser energy during the laser-assisted irradiation process. The fundamental reason for the change in the morphology and composition of the crystalline phases of the coatings is the induction and enhancement of the plasma discharge by laser-assisted irradiation. The photoelectrochemical behavior of the samples was evaluated by employing linear sweep voltammetry under continuous UV irradiation, and the photoresponse current density was measured under intermittent UV irradiation. The laser-assisted PEO coatings prepared with 80 W laser energy under laser-assisted irradiation exhibited the most favorable photoelectrochemical activity. Furthermore, further analysis showed that the enhanced photoelectrochemical activity of the photoactive titanium dioxide coatings was essentially due to a larger specific surface area, lower impedance, higher wettability, and a more suitable crystalline phase ratio.

Mechanical properties and microstructure of heterogeneous commercial pure titanium prepared by rotary swaging and annealing

Mechanical properties and microstructure of heterogeneous commercial pure titanium prepared by rotary swaging and annealing

Temperature-dependent behavior of CP-Ti interpreted via self-consistent crystal plasticity simulation

A commercially-pure titanium sample was investigated using an elasto-visco-plastic self-consistent polycrystal model. Temperature-dependent plastic deformation behavior was described by a dislocation density-based hardening model. The model reasonably reproduced various experimental behaviors, including stress vs. strain curves, diffraction lattice strains, twin volume fraction, and crystallographic texture. The temperature-dependent behavior was interpreted based on the dislocation evolution rules comprised of dislocation generation and recombination in accordance with the Kocks-Mecking rule. The modeling results successfully provided an in-depth interpretation of mechanical behavior of α-titanium under a wide range of temperatures.

Ceramic Conversion Treatment of Commercial Pure Titanium with a Pre-Deposited Vanadium Layer

Titanium is characterized by poor wear resistance which restricts its application. Ceramic conversion treatment (CCT) is used to modify the surface; however, it is a time-consuming process. In this work, a thin vanadium layer was pre-deposited on the commercial pure titanium (CPTi) samples’ surface, and it increased the oxygen absorption significantly and assisted in obtaining a much thicker oxide layer than those samples without a V layer at the treatment temperatures of 620 °C and 660 °C. The oxidation of the samples pre-deposited with the V layer had a much higher oxidation rate, and V was evenly distributed in the oxide layer. After CCT, all samples had a low wear volume and stable coefficient of friction in comparison to the untreated CPTi sample. A slightly higher wear area in the wear track was observed on the V pre-deposited samples than those samples without vanadium, especially those with a thicker oxide layer (&gt;4 µm). This might be associated with defects in a thicker oxide layer and insufficient support from a shallower oxygen diffusion zone or hard debris created at the initial stage. Vanadium in the oxide layer reduced the contact angles of the surface and increased the wettability significantly.

Achieving synergy of strength and ductility in powder metallurgy commercially pure titanium by a unique oxygen scavenger

Excessive interstitial oxygen (O) contamination, usually causing a dramatic loss of ductility, remains a longstanding challenge for titanium (Ti) and its alloys. Here, we propose to solve this critical problem by adding a minor CaC2 oxygen-scavenger via a simple powder metallurgy (PM) pressureless sintering approach. It is found that the surface oxide layer of hydride-dehydride (HDH) Ti powder begins to dissolve into the Ti matrix between 700 °C and 800 °C during the PM sintering process. The incorporation of CaC2 can react with the surface oxide layer (617-676 °C) prior to its active dissolution and form micrometer-sized TiC and nano-sized CaTiO3 particles, significantly refining the α-Ti grains and creating clean and well-bonded interface with Ti matrix. Therefore, the unique oxygen-scavenging effect by CaC2 produces high strength and superior ductility for Ti alloy. Even with an initially high oxygen content (∼4000 ppm), the Ti-0.4 wt.%CaC2 sample still exhibits a high ultimate tensile strength of 621±25 MPa and superior elongation of 29.3±2.6%, respectively. These values correspond to an increase of 17.6% and 301.4% compared to the as-sintered commercially pure titanium (CP-Ti) properties and far exceed the ASTM standard B381 for Grade 4 wrought Ti alloy (550 MPa and 15%) with the same O content. This work offers a novel method to develop high-strength and superior-ductility Ti materials from much more affordable Ti powder.

Effect of grain size and temperature on deformation mechanism of commercially pure titanium

To investigate the effects of grain size and processing temperature on the deformation behaviors of commercially pure titanium (CP-Ti), the tensile tests were conducted at room temperature (RT) and liquid nitrogen temperature (LNT) on the samples with the average grain size of 2, 9, 23, and 51 μm, respectively. The experimental results based on EBSD and TEM characterizations showed that dislocation slip was the main deformation mechanism at RT, while abundant deformation twins including {102} extension twins, {11} compression twins and some {11}−{102} secondary twins were observed under LNT condition. The transition of deformation modes from dislocation slip to dynamic twinning contributes to the outstanding mechanical properties of the samples with a larger grain size at LNT. Additionally, a modified Hall−Petch relationship was proposed to study the quantitative contribution of average grain size and deformation twins on yield stresses of CP-Ti under LNT condition.

Creation of a heterogeneous grain structure is a condition for increasing the low-temperature ductility of nanocrystalline hcp metals

The paper considers the influence of a heterogeneous (bimodal) grain structure on the ductility characteristics of commercial purity titanium in a wide range of low temperatures (4.2–395 K) as a strategy for optimizing mechanical properties within the framework of the “strength–plasticity” ratio. Using titanium as an example, the physical mechanism for increasing the low-temperature ductility of hcp nanocrystalline metals with a heterogeneous grain size distribution is explained by a combination of several processes: an increase in the activity of intragrain dislocation slip, dynamic grain growth under tensile stresses, and activation of nanotwinning in submicron-sized grains.

Dynamic recrystallization of commercially pure titanium during cryogenic compression

In this study, a systematic investigation on the twin-induced dynamic recrystallization (DRX) of commercially pure titanium (CP-Ti) was carried out under uniaxial compression at room (RT) and cryogenic temperature (CT, −150 °C). The compression tests were intentionally interrupted at 0.02, 0.05 and 0.1 strain levels at both deformation temperatures and a detailed post-mortem analysis was performed via electron backscattered diffraction (EBSD) to examine the progressive evolution of microstructure. The results revealed that two major types of twins i.e. {10−12} extension twin (ETW) and {11−22} compression twin (CTW) were effectively activated at both deformation temperatures. During RT deformation, increased strain levels resulted in the higher evolution of ETWs and CTWs, where numerous twin lamellas, lateral twin thickening and twin-twin interactions (ETW-ETW, ETW-CTW) were observed. On the other hand, CT deformation led to significant grain refinement with the average grain size reduced by 94% (3.7 μm for CT-10 sample as compared to 63 μm of initial material). The recrystallization kinetics were understood with respect to three region of interests (ROIs). The DRX mechanism was identified as tDRX, where intersectional {10–12} ETWs and {11–22} CTWs network provided the preferential sites for the nucleation of DRXed grains due to high strain energy from the dislocation pile-ups at the TBs.

Surface assessment of CNC laser treated commercially pure Titanium and Ti 13 Zr 13 Nb alloy

This study aimed to evaluate the surface changes of commercial pure Titanium disks (CP Ti) and the Ti 13Nb 13 Zr (Alloy) with a zigzag pattern of laser surface treatment. In vitro, experimental study of CNC Laser treatment on the CP Ti and Alloy disks. Texturing the surfaces of CP Ti and Alloy disks via CNC laser, the sample disks were analyzed using surface roughness, wettability and FESEM. The FESEM revealed a proper increase in the surface texturing and roughness on macro and micro measures without crack formation or dramatic change of the core substance of the CP Ti and Alloy disks. The CNC laser is an effective and suitable method for surface texturing CP Ti and Alloy for dental implantology. Keywords: Commercial pure Titanium; Ti 13 Zr 13 Nb alloy; CNC Laser; Laser surface texturing; Dental implant and surface roughness

Enhancing the corrosion behavior of Laser Powder Bed Fusion processed CP-Ti via Ultrasonic Peening

Surface modification of metal Additive Manufacturing (AM) components has gathered a lot of interest recently. Ultrasonic Peening (UP) was employed to improve the corrosion properties of Laser Powder Bed Fusion (L-PBF) processed commercially pure titanium (CP-Ti). UP process forged the surface porosities, significantly refined the acicular martensites (α'-M) formed during the L-PBF, and homogenized the microstructure. These significantly enhanced the corrosion behavior of L-PBF processed CP-Ti, by reducing the corrosion current from 4.8 µA/cm2 to 0.72 µA/cm2 after a 3-pass UP. Accordig to the FESEM observations, the corroded surface of the 3-pass UPed sample was covered by a protective oxide film implying its uniform corrosion.