Electrochemical corrosion behavior of biomedical Ti–22Nb and Ti–22Nb–6Zr alloys in saline medium

The aims of this study were to investigate the effects of Zr addition and potentiodynamic polarization on the microstructure and corrosion resistance of Ti–22Nb and Ti–22Nb–6Zr alloy samples. The corrosion tests were carried out in 0.9% NaCl at 37 °C and neutral pH value, utilizing the OCP, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) techniques. The results of XRD and optical microscopy indicated that the addition of Zr stabilized the β phase, which plays a crucial role in the corrosion resistance improvement of the Ti–22Nb–6Zr alloy. From the polarization curves, it can be seen that the alloys exhibited a wide passive region without the breakdown of the passive films and also low corrosion current densities. In addition, the values of the corrosion current densities and passive current densities decreased with the addition of 6 at% Zr into the Ti–22Nb alloy. The EIS results of these two alloy samples after 1‐h immersion in 0.9% NaCl solution, and being fitted by R_S(Q_PR_P) model, suggested that the corrosion resistance of the passive films improved with the addition of Zr and only a single passive film formed on the surfaces. However, two time constants were observed for the Ti–22Nb and Ti–22Nb–6Zr alloy samples after potentiodynamic polarization, the spectra of which can be fitted using the R_s(Q_o(R_o(Q_bR_b))) model. In addition, the corrosion resistance of the two alloy samples was reinforced significantly because of polarization when compared to the immersed samples. All these observations suggested a nobler electrochemical behavior of the titanium alloys with the addition of Zr element and after polarization.     

Composition and processing effects on the electrochemical characteristics of biomedical titanium alloys

The electrochemical behaviour of the Ti–13Nb–13Zr and Ti–6Al–4V ELI alloys with martensitic microstructures was investigated by polarization and electrochemical impedance spectroscopy (EIS) in Ringer’s solution. The impedance spectra were interpreted by a two time-constants equivalent circuit. Both investigated alloys showed high corrosion resistance, but the thin and uniform passive film on the Ti–6Al–4V ELI alloy surface was more protective. The inner barrier and outer porous layer were highly resistant and capacitive. However, thicker and more porous passive film on the Ti–13Nb–13Zr alloy surface may be beneficial for osteointegration. The suitable thermomechanical processing improved the corrosion resistance of Ti–13Nb–13Zr alloy.     

In vitro corrosion resistance and cytotoxicity of novel TiNbTaZr alloy

A novel β type Ti35Nb2Ta3Zr alloy with low modulus (48 GPa) was fabricated using vacuum consumable arc melting. The corrosion resistance and cytotoxicity of Ti35Nb2Ta3Zr were evaluated. The open circuit potential, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods were used to determine the corrosion resistance. In Ringer's solution, Ti35Nb2Ta3Zr alloy exhibits better corrosion resistance, as compared to that of Ti6Al4V and Ti. The cytotoxicity tests indicate that the biocompatibility of Ti35Nb2Ta3Zr is as good as Ti and Ti6Al4V which are widely used in biomedical fields. Based on corrosion resistance and cytotoxicity, the novel β type Ti35Nb2Ta3Zr alloy can be considered as a potential biomaterial.     

新型TiNbTaZr合金的生物腐蚀性和细胞毒性(英文)

通过真空自耗电弧炉开发一种新型β钛合金Ti35Nb2Ta3Zr,其弹性模量仅为48GPa,探讨该合金的耐腐蚀性能和细胞毒性。在Ringer模拟体液中,通过测量开路电位、极化阻抗谱和极化曲线发现Ti35Nb2Ta3Zr的腐蚀性优于Ti6Al4V和Ti。细胞毒性试验证明Ti35Nb2Ta3Zr的生物相容性与目前临床常用的Ti6Al4V和Ti相当。因此,该新型β钛合金Ti35Nb2Ta3Zr具有良好的耐腐蚀性和生物相容性,未来作为生物材料具有广阔前景。     

Effects of the Zr and Mo contents on the electrochemical corrosion behavior of Ti–22Nb alloy

Ti–22Nb–xZr and Ti–22Nb–xMo (x = 0, 2, 4, 6, in atom percent) were prepared by an arc melting method. The alloys were solution‐treated at 1073 K for 1.8 ks followed by quenching them into ice water, and the electrochemical corrosion behavior in a 0.9% NaCl solution at 25 °C and neutral pH range of the solution‐treated alloys was evaluated by using electrochemical impedance spectroscopy, polarization curves and an equivalent circuit analysis. It was found that the microstructure of the solution‐treated Ti–22Nb alloy mainly contains β phase with small amount of α″ phase, and the addition of Zr or Mo to a Ti–22Nb alloy is efficient to stabilize the β phase. The resulting impedance parameters and passive current densities indicated that the corrosion resistance of the Ti–22Nb alloy was promoted significantly with the addition of Zr and Mo.     

Influence of Zr content on microstructure and mechanical properties of implant Ti–35Nb–4Sn–6Mo–xZr alloys

The influence of Zr content on the microstructure and mechanical properties of implant Ti–35Nb–4Sn–6Mo–xZr (x=0, 3, 6, 9, 12, 15; mass fraction) alloys was investigated. It is shown that Ti–35Nb–4Sn–6Mo–xZr alloys appear to have equiaxed single β microstructure after solution treatment at 1023 K. It is found that the grains are refined first and then coarsened with the increase of Zr content. It is also found that Zr element added to titanium alloys has both the solution strengthening and fine-grain strengthening effect, and affects the lattice parameters. With increasing the Zr content of the alloys, the strength increases, the elongation decreases, whereas the elastic modulus firstly increases and then decreases. The mechanical properties of Ti–35Nb–4Sn–6Mo–9Zr alloy are as follows: σ_b=785 MPa, δ=11%, E=68 GPa, which is more suitable for acting as human implant materials compared to the traditional implant Ti–6Al–4V alloy.     

Stability of the passive state of Zr–Nb crystalline alloys

Stability of the passive state was assessed for pure Zr and four Zr–Nb alloys (2.5, 5.0, 10.0, 25.0 at.% Nb) after 24 h exposure to naturally aerated 3.5% NaCl solution (pH = 6). Open circuit potential values indicated that all the Zr–Nb alloys studied and the pure Zr undergo spontaneous passivation due to spontaneously formed oxide film passivating the metallic surface. It also indicated that the addition of increasing Nb contents to pure Zr seems to improve the protection characteristics of its spontaneous oxides. Potentiodynamic polarization curves showed an increase of the breakdown potential and the extent of the passive range following an increased niobium amount in the alloy. This leads to the conclusion that a progressive increase of niobium content positively affects the localized corrosion behaviour of the Zr–Nb alloys by enhancing the electrochemical stability of the passive film. Electrochemical impedance spectroscopy (EIS) studies showed high impedance values for all the samples, and its increase on increased niobium content in the alloy indicated an improvement in the corrosion resistance of the spontaneous oxide film. The fit obtained suggests a single passive film present on the metal surface, with resistance improving with the increase of niobium amount in the alloy. All these electrochemical results show the beneficial effect of increasing niobium contents on the passive state stability of the Zr–Nb alloys.     

Corrosion behaviors of a new titanium alloy TZNT for surgical implant application in Ringer's solution

A new near α-titanium alloy Ti12.5Zr2.5Nb2.STa (TZNT) for surgical implants was designed. The potentiodynamic technique was per-formed to investigate the corrosion behaviors of TZNT in Ringer's solution, and Ti6A14V, Ti6A17Nb, and TA2 were taken as comparison. The structure of the passive film was analyzed using an X-ray photoelectron spectrometer (XPS). The results indicate that TZNT possesses better corrosion resistance, when compared with Ti6A14V, Ti6A17Nb, and TA2. The passive film formed on the TZNT surface is composed of oxides, such as TiO_2, ZrO_2, Nb_2O_5, and Ta_2O_5. The elements Zr and Ta are rich, whereas Ti and Nb are poor in the passive film. The addi-tion of Zr, Nb, and Ta with relatively low electrochemical reaction potentials can reduce the anode activity and improve passive properties. Other than that, oxides such as ZrO_2, Nb_2O_5, and Ta_2O_5 with the nobler equilibrium constants make the passive film more stable.     

Large gap joining of Ti–6Al–4V alloy with mixed powder interlayers

Abstract

Titanium based brazing alloys containing chromium, iron, copper, and nickel as β stabilisers have been studied for joining the titanium alloy Ti–6Al–4V. Two of these alloys were selected for use in producing large gap joints. The first brazing alloy, Ti–12Zr–14Cr–12Cu–12Ni (type 1), can be used to braze Ti–6Al–4V below its β transus temperature. Joints of thickness up to 150 μm can be made in a normal brazing cycle without prolonged holding. The interlayer consists of a β titanium alloy with no precipitation of intermetallic compounds. The second brazing alloy, Ti–12Zr–14Cr–6Fe–5Cu–5Ni (type 2), has to be brazed above the β transus temperature of Ti–6Al–4V. Its powders were mixed with pure titanium and Ti–6Al–4V powders and the mixture was used as the joining interlayer. Interlayers 5 mm in thickness were used to produce joints for microstructural examination and mechanical testing. It was found that residual pores in the interlayers were related to the amount of the brazing alloy in the interlayer. A fully dense interlayer could be obtained with 60 wt-% brazing alloy in the interlayer. The as bonded joints revealed tensile strength equal to 50% of that of the base metal. Diffusional treatment of the joints improved the joint efficiency to about 70%, compared with the base metal.     

Evolution of deformation mechanisms of Ti–22.4Nb–0.73Ta–2Zr–1.34O alloy during straining

The plastic deformation behavior of Ti–22.4Nb–0.73Ta–2Zr–1.34O alloy was investigated by compression testing at room temperature. The multi-peak stress oscillations of the true stress–strain curve, characterized by a stress plateau, initial strain-hardening, followed by strain-softening and a second strain-hardening stages, is observed in a titanium alloy for the first time. The experimental results show that the above four-stage plastic deformation behavior is caused by a change in the dominant deformation mechanisms. At the stress plateau stage, the alloy deforms via multiple plastic deformation mechanisms. The initial strain hardening is caused mainly by tangling of dislocations. Subsequent strain softening is due to the formation of kink bands. The second strain hardening corresponds to the formation of shear bands. The above results suggest that the dominant deformation mechanisms of Ti–Nb–Ta–Zr–O alloys are related not only to the stability of the β phase, but also to the extent of plastic deformation.     

Effect of composing element on microstructure and mechanical properties in Mo–Nb–Hf–Zr–Ti multi-principle component alloys

A series of non-equiatomic Mo–Nb–Hf–Zr–Ti alloys are synthesized to investigate the effects of the concentration variation of each composing elements on the microstructure and mechanical properties. It is found that all studied alloys form single body-centered-cubic (BCC) phase only with the variation of the lattice parameter, which indicates that the concentration variation of each composing elements has no effect on the phase constitutes. All studied alloys exhibit typically dendritic and interdendritic structure while the concentration variation of each composing elements has different effects on the microsegregation. The concentration variation of Zr leads to the most serious microsegregation. Elements with a higher melting point such as Mo and Nb solidify preferentially and thus are enriched in the dendrites. Both the increase and decrease of the concentration of each composing element reduce the hardness and strength of non-equiatomic Mo–Nb–Hf–Zr–Ti alloys compared with the equiatomic MoNbHfZrTi alloy.     

时效强化高镍Inconel-718合金低周疲劳性能及寿命预测

研究了核反应堆弹簧材料用时效强化0Cr20Ni55Mo3Nb5Ti(Inconel-718)合金材料在350 ℃高温下的低周疲劳性能,并采用Manson-Coffin和郑修麟模型对加载应变水平和低周疲劳寿命之间关系进行了拟合计算和对比。结果表明:经过970 ℃×1 h空冷+720 ℃×8 h炉冷+620 ℃×8 h空冷热处理后,Inconel-718合金在350 ℃具有优异的低周疲劳性能。根据郑修麟关系式计算结果,其临界应变疲劳极限约为0.37%,在低于此应变水平条件下,其低周疲劳寿命高于10⁷循环。Manson-Coffin模型由于不包含临界应变疲劳极限参数ε₀,导致其对较低应变水平的疲劳寿命预测精度较低。     

Effect of La on the crystalline and electrochemical properties of Ti-Zr-Ni melt-spun alloys

Ti45Zr30Ni25 and Ti45Zr30Ni25La alloys were prepared by melt-spinning, and the phase structure and electrochemical performances of the melt-spun alloys were investigated. The results showed that the Ti45Zr30Ni25 alloy was composed of the quasicrystalline phase, amorphous phase and Laves phase. The Ti445Zr30Ni25La alloy contained quasicrystalline and amorphous phases. The maximum discharge capacity was 111 mAh/g for the Ti45Zr30Ni25 alloy electrode, and 124 mAh/g for the Ti45Zr30Ni25La alloy electrode. The Ti45Zr30Ni25La alloy electrode ex-hibited a better high-rate dischargeability and cycling stability than the Ti45Zr30Ni25 alloy electrode. The improvement of electrochemical properties was mainly ascribed to the increase in the amorphous phase due to the addition of La.     

Outstanding Mild Wear Performance of Ti–29Nb–14Ta–4.5Zr Alloy Through Subsurface Grain Refinement and Supporting Effect of Transformation Induced Plasticity

Metals and Materials International - The tribological performance of Ti–29Nb–14Ta–4.5Zr alloy against Ti–6Al–4V ELI was investigated for the mild condition, emphasized...     

加钛方式及钛含量对A356合金的低周疲劳性能的影响

研究了不同加钛方式和钛含量对A356合金低周疲劳性能的影响，结果表明A356合金的循环硬化行为对合金的加钛方式和钛含量敏感。钛含量为0．14％的合金总是比钛含量为0．10％的合金具有更高的循环硬化率。在低应变时两种加钛方式的循环硬化行为类似，在高应变时电解加钛合金表现为类似“饱和”的准稳定形变状态，而熔配加钛合金表现为持续的循环硬化行为。疲劳寿命仅对含钛量敏感，钛含量为0．10％时合金的低周疲劳寿命要优于钛含量为0．14％的合金。但是加钛方式对疲劳寿命的影响很小，如果钛含量相近，则两种加钛方式合金的低周疲劳寿命差别不大。     

Microstructure and properties of novel quinary multi-principal element alloys with refractory elements

Five equiatomic alloys(Ti Zr Hf VNb, Ti Zr Hf VTa, Ti Zr Nb Mo V, Ti Zr Hf Mo V and Zr Nb Mo Hf V) composed of five elements with high melting temperature, respectively were prepared by arc-melting to develop a novel high temperature alloy. The five alloys exhibit different dendritic and interdendritic morphologies. The Ti Zr Hf VNb, Ti Zr Hf VTa and Ti Zr Nb Mo V alloys formed disordered solid solution phases with body-centered cubic structure, and exhibited high compressive strength and good plasticity. The Ti Zr Hf Mo V and Zr Nb Mo Hf V alloys are composed with Laves phase(Hf Mo2) and disordered solid solution phases with body-centered cubic structure. The Ti Zr Hf Mo V and Zr Nb Mo Hf V alloys are harder and more brittle than the other three alloys due to the existence of hard and brittle Laves phases. At high temperatures, the strength decreases to below 300 MPa for the Ti Zr Hf VNb and Ti Zr Hf Mo V alloys. Solution strengthening is the primary strengthening mechanism of the Ti Zr Hf VNb, Ti Zr Hf VTa and Ti Zr Nb Mo V alloys, and brittle Laves phase is the main cause for the low ductility of the Ti Zr Hf Mo V and Zr Nb Mo Hf V alloys.     

氢对Ti-2Al-2.5Zr钛合金疲劳性能的影响

研究了4种含量的氢对Ti-2Al-2.5Zr钛合金疲劳性能的影响。结果表明，自然含氢量的材料具有最好的疲劳性能。而当疲劳载荷大于材料的屈服强度时，氢含量对疲劳寿命基本没有影响；低于屈服强度后，疲劳寿命随着氢含量的升高而和。认为固溶的原子氢导致驻留滑移带软化，裂纹萌生提前，造成在较大△σ时充氢试样的疲劳寿命降低；而材料中氢化物对驻留滑移带（PSB）的阻碍作用导致氢化物与基体分离 而成为裂纹源，是小△σ下疲劳寿命降低扩要原因。     

一种铜基电阻焊电极合金

报道了一种新的无Ｃｏ，低Ｂｅ电阻焊电极合金Ｃｕ－Ｎｉ－Ｚｒ－Ｂｅ－Ｔｉ（Ｂ合金）。将其组织性能同常用的Ｃｕ－Ｃｏ－Ｂｅ（Ａ合金）电极合金作了对比分析。结果表明，Ｂ俣金硬度，软化度同Ａ合金相近，但导电、导热性明显高于Ａ合金 。     

Nb—Ti—Ni合金的显微组织与氢渗透性能

研究了Nb50Ti25Ni25及Nb40Ti30Ni30合金的显微组织及氢渗透性能,并与贵金属Pd、Pd-Ag合金及纯Nb的氢渗透性能进行了比较.两种合金的显微组织均由先析出的bcc-Nb(Ti,Ni)固溶体和bcc-Nb(Ti,Ni) B2-TiNi共晶组成.随Ni、Ti合金元素含量增加,合金中共晶相的含量增加.氢渗透温度为673 K时,两种合金的氢渗透系数分别为1.71×10-8和1.03×10-8mol·in-1·s-1·Pa-0.5,接近Pd的氢渗透系数,略低于Pd-Ag合金的氢渗透系数.共晶相的比例增加有利于提高合金的抗氢脆性能,增加先析出相的比例可提高合金的氢渗透系数.适当调整合金元素含量可获得综合性能良好的氢渗透合金.     

Crystallographic and electrochemical characteristics of melt-spun Ti-Zr-Ni-Cu alloys

Ti44Zr32Ni22Cu2 and Ti41Zr29Ni28Cu2 alloys were prepared by the melt-spinning method. The phase structure was analyzed by X-ray diffraction,and the electrochemical performances of the melt-spun alloys were investigated. The results indicated that the Ti44Zr32Ni22Cu2 alloy was composed of the icosahedral quasicrystals and amorphous phases,and the Ti41Zr29Ni28Cu2 alloy comprised icosahedral quasicrystals,amorphous,and Laves phases. The maximum discharge capacity was 141 mAh/g for the Ti44Zr32Ni22Cu2 alloy and 181 mAh/g for the Ti41Zr29Ni28Cu2 alloy,respectively. The Ti41Zr29Ni28Cu2 alloy also showed a better high-rate dischargeability and cycling stability. The better electrochemical properties should be ascribed to the high content of Ni,which was beneficial to the electrochemical kinetic properties and made the alloy more resistant to oxidation,as well as to the Laves phase in the Ti41Zr29Ni28Cu2 alloy,which could work as the electro-catalyst and the micro-current collector.