Ti 13Nb 13Zr Research Articles

Comparative Study of Mechanical and Functional Properties of Age-Hardened Superelastic Ti–Zr–Nb Alloy with Different Initial Microstructures

Comparative Study of Mechanical and Functional Properties of Age-Hardened Superelastic Ti–Zr–Nb Alloy with Different Initial Microstructures

A strategy for designing Ti-based in-situ bulk metallic glass composites with tailored structural metastability using conventional titanium alloys

The metastability of the dendritic phase is crucial in determining the mechanical properties and mechanisms of the Ti-based in-situ dendrite-reinforced bulk metallic glass composites (BMGCs). However, tailoring the metastability effectively remains challenging. In this study, we propose a straightforward and effective strategy to tailor the dendrites composition and metastability using conventional Titanium alloys. Initially, six common Titanium alloys with increasing content of β-stabilizing elements such as Ti, Ti–6Al–4V, Ti–13Nb–13Zr, Ti–15Mo, Ti–12Mo–6Zr–2Fe and Ti-4.5Fe-6.8Mo-1.5Al were selected. Subsequently, a series of in-situ dendrite-reinforced BMGCs denoted as T1-T6 were designed by alloying these Titanium alloys with a specific amorphous alloy. It was found that the microstructure, stability and mechanical behaviors of these composites change significantly as the content of β-stabilizing elements in the dendritic phase increases monotonically. Based on their microstructure and mechanical behaviors, these composites can be classified into three categories: T1, T2 and T3, T4-T6. The T1 alloy exhibits brittle deformation characteristics due to the significantly higher elastic modulus of the dendritic phase. In contrast, the T2 and T3 alloys demonstrate good tensile plasticity and remarkable work-hardening ability, attributed to the metastable β phase undergoing stress-induced phase transformation during deformation. On the other hand, the T4-T6 alloys, consisting of stable β phase, deform via dislocation slip, resulting in a higher yielding stress and compression plasticity. The composition design strategy presented in this study, along with the correlation between mechanical behaviors and dendrite stability, may offer a novel perspective for the development of Ti-based in-situ dendrite-reinforced BMGCs.

Effect of Mn content on the microstructure, mechanical properties and corrosion behavior of Ti–Nb–Zr–Mn alloys processed via spark plasma sintering

Herein, β-type Ti–Nb–Zr–Mn alloys were prepared by ball milling and spark plasma sintering. The effects of Mn addition and quenching treatment on the microstructure, mechanical properties, and corrosion behavior of the alloy were investigated. The Ti–Nb–Zr–Mn alloys are predominantly constituted of equiaxed β Ti grains with a small proportion of ω phase. An increase in Mn content inhibits the precipitation of the ω phase while promoting a more homogeneous solid solution. The tensile strength of the as-prepared alloys decreases and then increases, whereas the plasticity demonstrates the opposite trend. The Elastic modulus and hardness roughly show a trend of decreasing and then increasing. Additionally, the Ti–24Nb–4Zr–2Mn alloy, after undergoing a solid solution treatment at a temperature of 950 °C and subsequent water quenching (referred to as M2-950), demonstrates exceptional comprehensive performance, showing a yield strength of 956 ± 4 MPa, an ultimate strength of 995 ± 13 MPa, an elongation of 16.4 ± 1.6 %, a hardness of 312 ± 11 H V, and an Elastic modulus of 72.6 GPa. Moreover, the corrosion behavior in Ringer's solution was extensively investigated, and the M2-950 alloy has superior corrosion resistance.

On the Mechanisms and Thermocyclic Stability of β → ωiso Transformation in a Superelastic Ti–Nb–Zr Shape Memory Alloy

On the Mechanisms and Thermocyclic Stability of β → ωiso Transformation in a Superelastic Ti–Nb–Zr Shape Memory Alloy

Influence of multiphase microstructure on the strength and ductility of Nb–Zr–Ti–V refractory high entropy alloys

In this investigation, we focused on the lightweight Nb–Zr–Ti–V alloys as representative model alloys to explore improving mechanical properties of refractory high entropy alloys (RHEAs) through phase engineering. The alloys were deliberately designed with different element concentrations and varied cooling rates after homogenization treatment, resulting in formation of multiple secondary phases. Microstructures of prepared alloys were reported, revealing the decomposition of the BCC matrix into dual-BCC phases with increasing V content. We attribute this phenomenon to the substantial atomic size misfit between V and Zr. Additionally, a metastable FCC phase and an intermetallic Laves phase emerged at intermediate temperatures in Nb0.75ZrTiV0.75, influenced by the nonequilibrium condition during cooling and the enthalpic effect. Compression tests were performed to access mechanical characteristics of different phases. The dual-BCC phases, featuring granular or multilayer morphology, enhanced ductility of the alloy by facilitating dislocation movement at BCC interfaces. In contrast, the FCC and Laves phases, characterized by a needle-like morphology, increased strength of the alloy owing to their intrinsic hardness. Based on the current discovery and understanding on secondary phases in the Nb–Zr–Ti–V alloys, our future objective is to obtain a modulated microstructure with an appropriate combination of different phases to optimize strength and ductility simultaneously.

Computationally guided alloy design and microstructure-property relationships for non-equiatomic Ti–Zr–Nb–Ta–V–Cr alloys with tensile ductility made by laser powder bed fusion

Single-phase body-centered cubic refractory complex concentrated alloys (RCCAs), exhibit strength retention at temperatures above the melting points of conventional Ni-based superalloys. However, their lack of room temperature tensile ductility leads to cracks during processing and/or premature failure under mechanical loading when fabricated by laser-based metals additive manufacturing (AM). We present an alloy design framework for tensile ductility in non-equimolar RCCAs amenable to AM processing within the Ti–V–Cr–Nb–Zr–Ta system. First, density functional theory (DFT) and machine learning informed screening of alloy compositions were used to down-select ∼106 alloys with potential for tensile ductility. Next, Scheil solidification modeling was used to eliminate compositions most at risk for micro-segregation and solidification cracking based on the estimated freezing range of each alloy. This led to the design of two new, representative alloys: Ti0.4Zr0.4Nb0.1Ta0.1 and Ti0.486V0.375Ta0.028Cr0.111. These alloys were evaluated for rapid solidification defect formation using in-situ synchrotron melt pool imaging, fabricated via laser powder bed fusion (L-PBF) AM, and then characterized for processing defects, microstructure, and mechanical properties. Overall, both alloys achieved tensile yield strengths >800 MPa and failure strains >5 %. However, the occurrence of un-melted powders of high melting point elements likely resulted in premature failure during tensile straining. Considerations about mitigating this defect source are discussed and the role of local micro-segregation on ductility are elucidated. Overall, these results highlight the success of our framework, and show potential for laser-based AM-RCCAs with tensile ductility.

Design and Development of Ti–Zr–Nb–Ta–Ag High Entropy Alloy for Bioimplant Applications

A new non‐equiatomic 35Ti–35Zr–20Nb–5Ta–5Ag at% high entropy alloy (HEA) is designed by combining the HEA concept with the properties required for bioimplants. Mechanical alloying is used to synthesize the HEA, which is then compacted at 550 and 700 MPa and sintered at 1300 °C. The phases, microstructure, and mechanical properties are investigated, and in vitro corrosion properties are studied in a simulated body fluid. After 20 h of mechanical alloying, a single body‐centered cubic (BCC) phase with a nanocrystalline size of 3.6 nm was formed. After sintering, the microstructure is composed of dual‐phase BCC structures: the major BCC 1 phase, the grain boundary BCC 2 phase, and the ultra‐fine equiaxed phase. The results of the micro‐indentation test indicate that the elastic modulus of the HEA is 84.4 ± 8.7 and 113.2 ± 13.36 GPa, and its Vickers microhardness is 3.47 ± 0.1 and 5.35 ± 0.2 GPa when it was compacted at 550 and 700 MPa respectively. The corrosion resistance tests reveal that HEA compacted at 700 MPa has higher corrosion resistance than commercial Ti6Al4V alloy. The developed Ti–Zr–Nb–Ta–Ag HEA has improved corrosion resistance and a lower elastic modulus, making it a potential candidate for bioimplant applications.

Evaluation of innovative fluroapatite /silicon dioxide modified zirconia nanocomposites coated on Ti–13Nb–13Zr alloy for dental implant application

Dental implants are intended to function as a durable method for replacing missing teeth. A biocompatible dental alloy is used to achieve integration with the jawbone through Osseointegration. This creates a strong base for the implant, allowing it to withstand the mechanical forces generated during biting and chewing. Dental alloys are commonly subjected to various mouth conditions known for their intricate corrosion potential. Corrosion can weaken the structural integrity of the implant, causing issues such as implant loosening, micro-motion at the implant-bone contact, implant fracture, allergic reactions, toxicity, and possible disruption of the Osseo integration process. To improve the alloy's corrosion resistance and biocompatibility, its surface can be altered using nanocomposite materials. The materials provide a protective coating to the alloy, creating a physical barrier that effectively prevents corrosive substances from reaching the underlying bulk material. This study involves modifying the surface of the dental alloy Ti–13Nb–13Zr with Fluroapatite (FAP)/Silicon dioxide (SiO2) modified zirconia (ZrO2) nano composites. The altered surfaces are then studied in simulated body fluid and artificial saliva solutions using in vitro methods. The FAP/SiO2 modified ZrO2 nanocomposites is applied onto a Ti–13Nb–13Zr alloy utilizing Electrophoretic deposition and Dip coating techniques. The coated samples were analysis utilizing FTIR, XRD, and SEM with EDS. Corrosion analysis was carried out on coated and uncoated samples using Electrochemical methods in simulated body fluid and artificial saliva solution. The biocompatibility is assessed using MTT assay, contact angle, and immersion testing in both SBF and Artificial saliva. EIS and corrosion study results show that FAP/SiO2 modified ZrO2 nanocomposites coated Ti13Nb13Zr alloy has high polarization resistance, low corrosion rate, and good charge transfer resistance, indicating excellent corrosion resistance. The contact angle study showed that the surface-modified Ti13Nb13Zr alloy is superhydrophilic, increasing implant surface osseointegration. Cell viability measurements reveal good cell growth, while immersion investigations show calcification, leading to enhanced osseointegration between the implant and its surrounding tissues. hence, it is an excellent material for dental implants application.

Understanding the Room Temperature Recovery Behavior in a Ti–24Nb–4Zr–8Sn Superelastic Alloy

Metastable β Ti–Nb‐based superelastic alloys have potential uses in the biomedical and aerospace industries due to an attractive combination of properties. However, their mechanical response can be seen to vary with cycling, limiting their uptake. Furthermore, recent studies have also highlighted changes in properties under no applied stress at room temperature, with the reasons for these changes poorly understood. To investigate potential mechanisms for these changes, the superelastic behavior of Ti–2448 is studied during mechanical cycling both pre‐ and post‐room temperature (RT) aging treatments. On cycling, there is a reduction in both σSIM and hysteresis area, consistent with behavior commonly seen in the literature. However, during RT aging, there is a rapid, time‐dependent process leading to a partial recovery. In situ diffraction data indicated that this recovery is coincident with a reduction in internal stresses, the potential mechanisms for which are discussed.

Effects of Nitrogen Doping on Microstructures and Irradiation Resistance of Ti–Zr–Nb–V–Mo Refractory High-Entropy Alloy

Effects of Nitrogen Doping on Microstructures and Irradiation Resistance of Ti–Zr–Nb–V–Mo Refractory High-Entropy Alloy

Incorporating microstructural and mechanical heterogeneity to Ti–Zr–Nb alloy by partial high-energy ball milling

This study introduced a novel method for incorporating microstructural and mechanical heterogeneity into Ti–Zr–Nb alloy to improve its strength without significantly affecting the elastic modulus. Ti–Zr–Nb alloy powder was milled at different ball-milling energies using a planetary ball mill, mixed with parent pristine powder in equal weight fractions using a horizontal ball mill, and sintered using spark plasma sintering. The resulting bimodal-like microstructure showed an increase in tensile yield strength (up to 410 MPa) without significant changes in the elastic modulus (<6 GPa). Milling followed by sintering caused grain refinement and precipitation in the relevant zones of the sintered samples, resulting in a heterogeneous structure due to the unique spread of α-precipitates. The strength of the heterogeneity-incorporated alloys was improved as a function of milling while maintaining high plasticity and a low elastic modulus.

Antibacterial properties, biocompatibility and superelastic behavior of Au-cysteine-gentamicin-functionalized Ti–Zr–Nb alloy

Superelastic Ti–18Zr–15Nb alloy capable of mimicking the mechanical behavior of a bone tissue is a promising biomaterial but suffers from the lack of antibacterial properties. To address this problem, we developed a combined surface treatment method: formation of a porous sub-surface layer, deposition/precipitation of Au nanoparticles (AuNPs), surface functionalization with cysteine amino acid and grafting of gentamicin. The sizes distribution and AuNPs content were greatly effected by the synthesis methods. The AuNPs with an average size of 3 nm were obtained by precipitation from a AuNP colloidal solution. Larger AuNPs were formed by preliminary alloy functionalization in a NaBH4 solution followed by treatment in a HAuCl4 solution. Successful surface functionalization with L-cysteine and attachment of gentamicin were confirmed by XPS analysis. Due to the formation of stable cysteine-gentamicin complexes attached to AuNPs, the materials showed high antibacterial activity against Escherichia coli and Staphylococcus aureus strains. Better antibacterial properties are ascribed to fine isolated AuNPs as compared to larger ones. Cytocompatibility was assessed for osteoblast cells. In the case of smaller AuNPs, an accelerated restoration of osteoblastic cell proliferation and a more organized actin cytoskeleton were observed. Hemolytic activity of the developed materials was investigated. Functional mechanical properties were not affected by the surface treatment.

Study on Osseointegration Capability of β-Type Ti-Nb-Zr-Ta-Si Alloy for Orthopedic Implants.

Osseointegration is the basic condition for orthopedic implants to maintain long-term stability. In order to achieve osseointegration, a low elastic modulus is the most important performance indicator. It is difficult for traditional titanium alloys to meet this requirement. A novel β-titanium alloy (Ti-35Nb-7Zr-5Ta)98Si2 was designed, which had excellent strength (a yield strength of 1296 MPa and a breaking strength 3263 MPa), an extremely low elastic modulus (37 GPa), and did not contain toxic elements. In previous in vitro studies, we confirmed the good biocompatibility of this alloy and similar bioactivity to Ti-6Al-4V, but no in vivo study was performed. In this study, Ti-6Al-4V and (Ti-35Nb-7Zr-5Ta)98Si2 were implanted into rabbit femurs. Imaging evaluation and histological morphology were performed, and the bonding strength and bone contact ratio of the two alloys were measured and compared. The results showed that both alloys remained in their original positions 3 months after implantation, and neither imaging nor histological observations found inflammatory reactions in the surrounding bone. The bone-implant contact ratio and bonding strength of (Ti-35Nb-7Zr-5Ta)98Si2 were significantly higher than those of Ti-6Al-4V. The results confirmed that (Ti-35Nb-7Zr-5Ta)98Si2 has a better osseointegration ability than Ti-6Al-4V and is a promising material for orthopedic implants.

Finite element analysis of the mechanical performance of self-expanding endovascular stents made with new nickel-free superelastic β-titanium alloys

New Ni-free superelastic β-titanium alloys from the Ti–Zr–Nb–Sn system have been designed in this study to replace the NiTi alloy currently used for self-expanding endovascular stents. The simulation results, carried out by finite element analysis (FEA) on two β-type Ti–Zr–Nb–Sn alloys using a commonly used superelastic constitutive model, were in good agreement with the experimental uniaxial tension data. An ad-hoc self-expanding coronary stent was specifically designed for the present study. To assess the mechanical performance of the endovascular stents, a FEA framework of the stent deployed in the arterial system was established, and a simply cyclic bending loading was proposed. Six comparative simulations of three superelastic materials (including NiTi for comparison) and two arterial configurations were successfully conducted. The mechanical behaviours of the stents were analysed through stress localization, the increase in artery diameter, contact results, and distributions of mean and alternating strain. The simulation results show that the Ti–22Zr–11Nb–2Sn (at. %) alloy composition for the stent produces the largest contact area (9.92 mm2) and radial contact force (49.5 mN) on the inner surface of the plaque and a higher increase in the stenotic artery diameter (70 %) after three vascular bending cycles. Furthermore, the Ti–22Zr–11Nb–2Sn stent exhibited sufficient crimping capacity and reliable mechanical performance during deployment and cyclic bending, which could make it a suitable choice for self-expanding coronary stents. In this work, the implementation of finite element analysis has thus made it possible to propose a solid basis for the mechanical evaluation of these stents fabricated in new Ni-free superelastic β-Ti alloys.

Mechanical property of the shape memorable Ti–Zr–Nb–Sn alloy manufactured by in-situ alloying in directed energy deposition

Ni-free β-type Ti alloys have been developed to manufacture high-strength, low-elastic-modulus, shape-memorable medical, and non-toxic components. Because the machinability of these alloys is generally poor, processing via additive manufacturing is an important step in the development of order-made medical devices. Although many studies evaluated the mechanical properties of additively manufactured Ni-free β-type Ti alloys, investigation of their heterogeneous microstructure resulting from the rapid melting-solidification cycling has not been discussed yet. In this study, the role of a heterogeneous microstructure on the performance of an in-situ alloyed Ti–Zr–Nb–Sn alloy was investigated. The metastable and nanosized ω phase, which is initiated in the non-equilibrium environment, enhances the yield strength without severe ductility degradation. Additionally, deformation-induced martensitic transformation occurs near the unmelted particle/matrix interface, and this phase transformation not only contributes to transformation-induced plasticity but also provides a superelasticity to the present alloy. Although the remained partially melted particle induces a localized corrosion in the matrix, the present results show that the heterogeneous microstructure of the in-situ alloyed Ti–Zr–Nb–Sn alloy exhibits outstanding mechanical properties and superelasticity, which will be suitable to fabricate biomedical parts via additive manufacturing.

Analysis of physical, chemical, mechanical, and microbiological properties of Ti–35Nb–7Zr–5Ta and Ti–6Al–4V discs obtained by machining and additive manufacturing

The objective was to compare the physical, chemical, mechanical, and microbiological properties between discs (n = 10) of Ti–6Al–4V and Ti–35Nb–7Zr–5Ta (TNZT) obtained by Machining (M) and additive manufacturing (AM) by Laser Powder Bed Fusion technique to identify the influence of chemical composition and processing technique on material properties. Using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), x-ray diffraction (XRD), wettability, surface free energy, roughness by confocal laser microscopy and atomic force microscopy (AFM), Vickers microhardness (VM), and colony forming units (CFU) against S. aureus. Two-way ANOVA (p < 0.05) was applied. Higher roughness and irregularity were observed in the AM discs. The chemical composition of the EDX alloys was compatible with the concentrations expected and available in the literature. For TNZT the manufacturing technique interfered in the present phases (α and β) due to different cooling rates. The wettability and surface free energy of TNZT was higher than that of Ti–6Al–4V, and there was no significant difference for the manufacturing techniques. Ti–6Al–4V showed greater hardness than TNZT and the M technique greater than AM. There was no difference in S. aureus CFU between the groups. It was concluded that TNZT alloy showed higher hydrophilicity, surface free energy, roughness, lower hardness, manufacturing techniques that interfered in its phases, and no differences for CFU compared to Ti–6Al–4V. The AM technique generated more irregular and rough surfaces, and lower hardness, without significant changes concerning M in terms of chemical composition, wettability, surface free energy, and bacterial formation.

The interdependence of the thermal and mechanical cycling behaviour in Ti2448 (Ti–24Nb–4Zr–8Sn, wt%)

Metastable β Ti alloys based on the Ti–Nb system have received increased attention in recent years due to an attractive range of properties. This includes their ability to undergo martensitic phase transformations on application of a stress, or on cooling below a critical temperature. However, the cyclic behaviour of these materials is unstable, which is a significant barrier to widespread industrial use. Recently, both the thermal and mechanical aspects of the transformation have been shown to be highly sensitive to the presence of internal stresses, which include a contribution from the dislocations produced as a necessary product of the transformation to provide geometric continuity at the phase boundary. It has been hypothesised that these dislocations may be responsible for the unstable cyclic behaviour. Redistribution of these dislocations and their associated stresses at elevated temperatures provides a novel mechanism by which unstable cyclic behaviour can be mitigated. Hence, in this work, in situ synchrotron characterisation is used to assess the effect of thermal cycling subsequent to mechanical loading on the superelastic transformation in a commercial Ti–Nb alloy. For the first time, it was shown that unstable cyclic behaviour can be avoided through the use of inter-cycle thermal treatments, which represents a significant breakthrough in our understanding of Ti–Nb superelastic materials.

Microstructure and Mechanical Characteristics of µ-Plasma Additively Manufactured Equiatomic Ti–Nb–Zr–Mo–Ta HEA

Microstructure and Mechanical Characteristics of µ-Plasma Additively Manufactured Equiatomic Ti–Nb–Zr–Mo–Ta HEA

Superelastic properties of biomedical Ti–Zr–Nb–Sn highly porous shape memory alloys prepared by fiber metallurgy

Artificial bone substitutes to satisfy the specific properties of cancellous bone for the repair of bone defects are highly desirable. In this study, combining the unique superelasticity and high porosity, biomedical Ti–Zr–Nb–Sn highly porous shape memory alloys (HPSMAs) were prepared by fiber metallurgy for the potential repair of damaged cancellous bone. Three-dimensional and open porous networks constructed by fiber-fiber bonds were obtained in the HPSMAs with a porosity of 79.5%. The recovery strain at room temperature was improved from 2.3% in the as-sintered specimen to 3.8% in the 700 °C solution-treated one by adjusting the transformation temperature. The mechanical performances in the Ti–Zr–Nb–Sn HPSMAs were similar to those of cancellous bone. Stable superelastic behaviors with a recovery strain of 4% were achieved at room temperature after cycle training. The Ti–Zr–Nb–Sn HPSMAs satisfy those specific properties of cancellous bone and show great potential in the repair of cancellous bone defects.

Microstructure and mechanical properties evolution of Ti-13Nb-13Zr alloy processed by ECAP-Conform and rotary swaging

The evolution of the microstructure and properties of Ti-13 Nb-13Zr alloy was investigated for the materials states ranging from the solution treated (ST) state over the continuous equal channel angular pressing (ECAP-Conform) state to the states of the materials processed by combination of ECAP-Conform with rotary swaging (RS) multilevel deformation. In order to investigate microstructure features and mechanical properties for all considered material states, SEM, TEM, XRD and tensile and hardness tests were employed. The two-dimensional mismatch between α′, β, and α phases was calculated to evaluate the effect of the precipitation of the second phase. The results indicate that the microstructure of Ti-13 Nb-13Zr alloy transformed into majority of α′ martensite and a small percentage of residual metastable βm phase after ST. The grains were significantly refined, and a small part of α phase was precipitated during ECAP-Conform. As a result of ECAP-Conform + RS, the average grain size was refined from 34 µm after ST to 152 nm. The vast majority of the unstable phase was retained. Due to the ECAP-Conform + RS, the tensile strength increased to 1167.7 MPa while the elongation was 8.6%. The two-dimensional mismatch between α′, α, and β phases was 22.1%, which belongs to a semi-coherent relationship. The excellent mechanical properties were mainly attributed to the strengthening by α phase precipitation, dislocation strengthening, and grain refinement.