Ta含量对Ti-6Al-3Nb-2Zr-1Mo-xTa合金力学性能和腐蚀性能的影响

系统研究了Ti-6Al-3Nb-2Zr-1Mo-x Ta(x=0,0.2,0.5,1.0,3.0,5.0)合金的微观组织、拉伸性能、夏比冲击韧性和耐海水腐蚀性。结果表明,经α+β两相区锻造后,Ti-6Al-3Nb-2Zr-1Mo-5Ta合金获得片层组织,Ti-6Al-3Nb-2Zr-1Mo-x Ta(x=0,0.2,0.5,1.0,3.0)均获得双态组织。XRD、TEM和选区电子衍射表明,在添加Ta元素后,Ti-6Al-3Nb-2Zr-1Mo-x Ta合金没有新相产生。对于双态组织Ti-6Al-3Nb-Zr-1M0-x Ta合金,随着Ta含量的增加,其Mo当量逐渐增加,导致其屈服强度、抗拉强度和显微硬度均有所提高。而Ta含量对冲击吸收功的影响规律与屈服强度和抗拉强度的影响规律相反,其大小与冲击断口剪切唇区面积一致。当Ta含量超过1.0%(质量分数)时,由于α和β相之间的标准平衡电位差逐渐增大,Ti-6Al-3Nb-2Zr-1Mo-x Ta合金的耐海水腐蚀逐渐降低。综合考虑强度、冲击韧性和耐海水腐蚀性能,Ti-6Al-3Nb-2Zr-1Mo-1Ta合金综合匹配性最好,具有良好的海洋工程应用潜力。     

High-Temperature Oxidation Behavior of Ti-22Al-27(Nb, Zr) Alloys

研究了Ti2Al Nb基合金Ti-22Al-(27-x)Nb-x Zr(x=0,1,6,at%)在650~800℃的氧化行为。采用XRD和SEM等测试技术对此温度区间形成的氧化层特征进行了分析。结果表明,相比Ti-22Al-27Nb,含锆合金具有较好的抗氧化性能。Ti-22Al-(27-x)Nb-x Zr合金在650℃氧化100 h,主要氧化产物为Ti O2,而在800℃氧化100 h,Ti O2,Al2O3和Al Nb O4为主要产物,但是在Ti-22Al-21Nb-6Zr合金中还有Zr O2生成。Ti-22Al-26Nb-1Zr合金具有优异抗氧化性能,归因于氧化产物细化形成了致密的氧化层,而Ti-22Al-21Nb-6Zr合金,虽然在800℃也形成了较多Al2O3,但是氧化层中的Zr O2为氧的快速扩散提供通道,进而导致该合金氧化增重明显。     

Characterization of the Ti-10Nb-10Zr-5Ta Alloy for Biomedical Applications. Part 2: Wettability, Tribological Performance and Biocompatibility

The Ti-10Nb-10Zr-5Ta alloy, prepared in a levitation melting furnace, was investigated as a possible candidate for replacing Ti6Al4V alloy in medical applications. The sessile drop method, pin-on-disc and in vitro tests were used to analyze wettability, wear resistance, and biocompatibility of the new alloy. The characteristics of the Ti-10Nb-10Zr-5Ta alloy were assessed in comparison to those of the Ti6Al4V alloy. The Ti-10Nb-10Zr-5Ta system was found to have hydrophilic characteristics with similar contact angle as the Ti6Al4V alloy. In all environments (deionized water, simulated body fluid and Fusayama Meyer artificial saliva), the friction coefficient showed a stable evolution versus sliding distance, being similar for both alloys. On overall, the wear resistance of Ti-10Nb-10Zr-5Ta alloy was lower than that of Ti6Al4V for all testing environments. The Ti-10Nb-10Zr-5Ta alloy exhibited good biocompatibility characteristics at in vitro test compared to Ti6Al4V alloy. The cell viability on Ti-10Nb-10Zr-5Ta surfaces was higher than the one observed on Ti6Al4V samples, regardless the number of days spent in osteoblast-like cells culture. A high degree of cell attachment and spreading was observed on both alloys.     

Characterization of the Ti-10Nb-10Zr-5Ta Alloy for Biomedical Applications. Part 1: Microstructure, Mechanical Properties, and Corrosion Resistance

Ti-10Nb-10Zr-5Ta alloy was investigated as possible material candidate for replacing Ti6Al4V in medical applications. The alloy was prepared in a levitation melting furnace and characterized in terms of elemental and phase composition, microstructure, mechanical properties, and corrosion resistance in simulated body fluid and Fusayama Meyer artificial saliva solutions. The characteristics of the new alloy were compared to those of the Ti6Al4V alloy. The Ti-10Nb-10Zr-5Ta system was found to posses of a polyhedral structure consisting in α′ and β phases. X-ray structural analysis revealed a mixture of hexagonal α′ martensite (main phase, with grain size of about 21 nm) and β bcc phase. The Ti-10Nb-10Zr-5Ta alloy exhibited some better mechanical properties (Young modulus, tensile properties) and corrosion resistance (polarization resistance, corrosion current density, and corrosion rate), as compared to Ti6Al4V alloy.     

Electrochemical Behavior of Novel Superelastic Biomedical Alloys in Simulated Physiological Media Under Cyclic Load

The aim of the present work was to study corrosion and electrochemical behavior of Ti-22Nb-6Ta and Ti-22Nb-6Zr (at.%) superelastic alloys under conditions which imitate the performance mode of target devices (bone implants), i.e., under cyclic load in simulated physiological solutions. Open circuit potential (OCP) measurements were carried out on wire specimens in Hank’s solution and artificial saliva at 37 °C with various strain values up to 1.5%. It is shown that at clinically relevant strain values (about 0.2%) the alloys exhibit OCP growth indicating their high stability and resistance to corrosion fatigue under these cycling conditions. At much higher strains (about 1%), fatigue crack initiation and propagation take place, however, the corresponding OCP variation indicates that the fracture process is significantly restrained by reversible martensitic transformation during cycling.     

Electrochemical Behavior of Biomedical Titanium Alloys Coated with Diamond Carbon in Hanks’ Solution

Biomedical implants in the knee and hip are frequent failures because of corrosion and stress on the joints. To solve this important problem, metal implants can be coated with diamond carbon, and this coating plays a critical role in providing an increased resistance to implants toward corrosion. In this study, we have employed diamond carbon coating over Ti-6Al-4V and Ti-13Nb-13Zr alloys using hot filament chemical vapor deposition method which is well-established coating process that significantly improves the resistance toward corrosion, wears and hardness. The diamond carbon-coated Ti-13Nb-13Zr alloy showed an increased microhardness in the range of 850 HV. Electrochemical impedance spectroscopy and polarization studies in SBF solution (simulated body fluid solution) were carried out to understand the in vitro behavior of uncoated as well as coated titanium alloys. The experimental results showed that the corrosion resistance of Ti-13Nb-13Zr alloy is relatively higher when compared with diamond carbon-coated Ti-6Al-4V alloys due to the presence of β phase in the Ti-13Nb-13Zr alloy. Electrochemical impedance results showed that the diamond carbon-coated alloys behave as an ideal capacitor in the body fluid solution. Moreover, the stability in mechanical properties during the corrosion process was maintained for diamond carbon-coated titanium alloys.     

Effect of surface treatment on electrochemical behavior of CP Ti, Ti-6Al-4V and Ti-13Nb-13Zr alloys in simulated human body fluid

The effect of an alkaline surface treatment on the electrochemical behavior of CP titanium, Ti-6Al-4V and Ti-13Nb-13Zr has been investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Experiments were performed in Hank’s solution as a function of immersion time. The electrochemical behavior of untreated alloys was also studied. Potentiodynamic polarization experiments conducted after 1 and 168 h of immersion in Hank’s solution indicated minimal change in passive current density for the untreated alloys. EIS data obtained after 1, 24, 72 and 168 h for untreated alloys also indicated minimal change in passive film resistance. In the case of surface-treated alloys, EIS revealed the formation of one additional layer on CP Ti and two additional layers on Ti-6Al-4V and Ti-13Nb-13Zr alloys after surface treatment and immersion in Hank’s solution. Some ideas about the nature of these layers have been obtained by fitting the EIS data to equivalent electrical circuit models. The surfaces of the treated Ti-alloys were also characterized using X-ray diffraction and scanning electron microscopy. The first additional layer has been identified as a sodium titanate hydrogel layer and the second layer, as an apatite layer. The apatite nucleation and growth on the surface occurred after immersion in Hank’s solution. Ti-6Al-4V and Ti-13Nb-13Zr alloys exhibited higher apatite film resistance compared to CP Ti.     

生物医用钛合金的研究进展

钛合金具有较低的弹性模量、优异的耐腐蚀性能和生物相容性,是理想的生物医用材料.综述了医用钛合金的发展过程及新型医用β钛合金的研究现状,以及开发的新合金系列.目前开发的医用钛合金中,Ti-35Nb-7Zr-5Ta和Ti-29Nb-13Ta-7.1Zr合金的弹性模量为55 GPa,与致密骨的弹性模量很接近,与人体骨有较好的...     

Martensitic transformation of Ti-18Nb(at.%) alloy with zirconium

The addition of 3%～9% Zr on the martensitic transformation of Ti-18Nb(at.%) alloy was investigated. The results of microstructure and X-ray diffraction (XRD) analysis show that the phase constitution of as-quenched Ti-18Nb-9Zr(at.%) alloy consists of the retained matrix and martensite, while that of the other three alloys is single martensite. No trace of athermal phase was found in any of the as-quenched alloys. Unlike the effect of Nb addition on the martensitic transformation start temperature Ms of Ti-1...     

新型医用Ti-24Nb-4Zr-8Sn合金在Hanks溶液中的电化学腐蚀行为研究

采用极化曲线分析、电化学阻抗谱（EIS）测试和浸泡实验的方法,并结合XPS,XRD和SEM等分析手段对新型医用Ti-24Nb-4Zr-8Sn合金在37℃的Hanks人工模拟体液中的电化学腐蚀行为进行了研究,并与纯Ti和Ti-6Al-4V合金进行了比较.结果表明:在37℃的Hanks溶液中,Ti-24Nb-4Zr-8Sn合金的腐蚀电流密度与纯Ti相等,并且钝化性能优于纯Ti和Ti-6Al-4V,这与其钝化膜中存在大量的Nb₂O₅密切相关;EIS结果显示,Ti-24Nb-4Zr-8Sn合金表面形成内层致密而外层疏松的双层钝化膜结构,致密层特性对材料的耐蚀性能起到决定性作用;随着浸泡时间的延长,致密内层的电阻大幅度提高,Ti-24Nb-4Zr-8Sn合金的耐蚀性能增强,同时疏松外层中的微缺陷发展成为宏观裂纹,造成疏松外层整体脱落.     

Effect of Cr on Microstructure and Fracture Toughness of Nb-20Ti-16Si-xCr Alloys

The present paper reported the phase stability and microstructures evolution of Nb-20Ti-16Si-xCr (x = 0～20at.%) in-situ composites as function of Cr addition. It was suggested that with the addition of Cr less than 7%, the silicide phase in as-cast Nb-20Ti-16Si alloy was Nb3Si. The silicides changed to be α-Nb5Si3 by the addition of Cr above 7%. It was found that annealing of 1300 ℃ for 100 h could result in the decomposition of Nb3Si to NbSS and α-Nb5Si3 in Cr containing Nb-20Ti-16Si based alloys by means ...     

粉末冶金Nb-35Ti-6Al-5Cr-8V合金组织演变及其力学行为

采用粉末冶金法对不同球磨时间的Nb-35Ti-6Al-5Cr-8V合金机械合金化粉末塑变行为,热压烧结材料的微观组织结构和力学行为进行了研究。研究结果表明：塑性良好的Nb-35Ti-6Al-5Cr-8V粉末随着球磨时间增加首先变形为大尺寸的片状、后经持续的加工硬化破碎成絮状;热压烧结能够制备微观组织可控晶粒细化的Nb-35Ti-6Al-5Cr-8V合金,合金由单一的Nbss相构成,Ti、Al、Cr、V元素固溶引起Nb晶格尺寸减小0.0685 ?;随着球磨时间增加合金晶粒明显细化进而显著提高了合金的维氏硬度和室温压缩强度,其变化符合材料硬度和强度的Hall-Petch规律。粉末冶金制备Nb-35Ti-6Al-5Cr-8V合金的各项力学性能明显优于熔铸法制备合金。     

Processing and properties of Nb- Ti- base alloys

The processing characteristics, tensile properties, and oxidation response of two Nb-Ti-Al-Cr alloys were investigated. One creep test at 650 °C and 172 MPa was conducted on the base alloy, which contained 40Nb-40Ti-10Al-10Cr. A second alloy was modified with 0.11 at.% C and 0.07 at.% Y. Alloys were arc melted in a chamber backfilled with argon, drop cast into a water-cooled copper mold, and cold rolled to obtain a 0.8-mm sheet. The sheet was annealed at 1100 °C for 0.5 h. Longitudinal tensile specimens and oxidation specimens were obtained for both the base alloy and the modified alloy. Tensile properties were obtained for the base alloy at room temperature, 400,600,700,800,900, and 1000 °C and for the modified alloy at room temperature, 400,600,700, and 800 °C. Oxidation tests on the base alloy and modified alloy, as measured by weight change, were carried out at 600,700,800, and 900 °C. Both the base alloy and the modified alloy were extremely ductile and were cold rolled to the final sheet thickness of 0.8 mm without an intermediate anneal. The modified alloy exhibited some edge cracking during cold rolling. Both alloys recrystallized at the end of a 0.5-h annealing treatment. The alloys exhibited moderate strength and oxi-dation resistance below 600 °C, similar to the results of alloys reported in the literature. The addition of carbon produced almost no change in either the yield strength or ductility as measured by total elonga-tion. A small increase in the ultimate tensile strength and a corresponding decrease in the reduction of area below 600 °C were observed. Carbon addition also served to marginally refine the grain size after annealing. The results of this study and those of similar alloys reported in the literature suggest that 40Nb-40Ti-10Al-10Cr forms a good base alloy suitable for alloying for improvement in its oxidation and high-temperature strength properties.     

Fatigue crack growth and fracture behavior of as-cast Ti-43.5Al-4Nb-1Mo-0.1B (TNM) compared to Ti-48Al-2Nb-2Cr (4822)

The effects of sample orientation and load ratio on the room-temperature fatigue crack growth and fracture behavior of a third-generation gamma titanium aluminide Ti-43.5Al-4Nb-1Mo-0.1B (TNM) were determined and compared with that of a second-generation alloy Ti-48Al-2Nb-2Cr (4822). Both materials are currently used as low pressure turbine blades in fuel-efficient gas turbine engines. Bend bar specimens, excised from the as-cast articles in the longitudinal and transverse directions to the casting direction, were tested at room temperature in lab air. Load ratios in the range 0.1–0.9 were used in fatigue testing to determine their effects on the fatigue threshold, Paris law slope, and stress intensity at overload in fatigue. Microscopy and fractography were used to document the effects of sample orientation on the fatigue crack path and morphology. Significant effects of changes in load ratio were observed on the fatigue threshold and Paris law slope, while effects of sample orientation were minimal for both alloys. The effects of microstructure length scale and differences in micro-constituents are discussed in relation to the properties measured.     

Properties of Porous TiNbZr Shape Memory Alloy Fabricated by Mechanical Alloying and Hot Isostatic Pressing

In the past decades, systematic researches have been focused on studying Ti-Nb-based SMAs by adding ternary elements, such as Mo, Sn, Zr, etc. However, only arc melting or induction melting methods, with subsequent hot or cold rolling, were used to fabricate these Ni-free SMAs. There is no work related to powder metallurgy and porous structures. This study focuses on the fabrication and characterization of porous Ti-22Nb-6Zr (at.%) shape memory alloys produced using elemental powders by means of mechanical alloying and hot isostatic pressing. It is found that the porous Ti-22Nb-6Zr alloys prepared by the HIP process exhibit a homogenous pore distribution with spherical pores, while the pores have irregular shape in the specimen prepared by conventional sintering. X-ray diffraction analysis showed that the solid solution-treated Ti-22Nb-6Zr alloy consists of both ?? phase and ???? martensite phase. Morphologies of martensite were observed. Finally, the porous Ti-22Nb-6Zr SMAs produced by both MA and HIP exhibit good mechanical properties, such as superior superelasticity, with maximum recoverable strain of ~3% and high compressive strength.     

Microstructure, mechanical, and anticorrosive properties of a new Ti-20Nb-10Zr-5Ta alloy based on nontoxic and nonallergenic elements

For an alloy to be suitable for use as an implant material, it must have a low specific weight and Young??s modulus, good mechanical properties that are similar to those of bone, and very good corrosion resistance and biocompatibility. In this study, we have developed a novel Ti-20Nb-10Zr-5Ta alloy that is composed of nontoxic, nonallergenic, corrosion-resistant elements. This alloy has low specific weight and Young??s modulus and good mechanical properties. It has a fine microstructure with a matrix that is mainly composed of the ?? phase and some ?? phase due to recrystallization during cooling. It shows elastoplastic behavior with a fairly linear elastic behavior and low Young??s modulus (59 GPa). In addition, its ultimate tensile strength, 0.2% yield strength, and hardness are higher than those of CP Ti, commercial Ti-6Al-4V, and similar ??-type alloys. It exhibited a very stable passive state and its electrochemical parameters and corrosion and ion release rates were better than those of CP Ti in Ringer??s solutions of different pH values that simulate the severe functional conditions of an implant; this is attributable to the beneficial influence of the alloying elements and to the better protective properties of the coated passive film.     

Effect of enamel coating on long-term oxidation and hot corrosion behavior of Ti-24Al-17Nb-0.5Mo alloys

The effect of enamel coating on long-term isothermal oxidation at 700 ℃ and cyclic oxidation at 800 ℃ in air and hot corrosion resistance of Ti-24Al-17Nb-0. 5Mo in 75% (Na2SO4 K2SO4 ) 25% NaCl (mass fraction) molten mixed salts at 700 ℃ was investigated. The results indicate that Ti-24Al-17Nb-0.5Mo alloy exhibits relatively poor long-term oxidation resistance due to the formation of Al2O3 TiO2 Nb2O5 mixed scales and poor hot corrosion resistance due to the spallation of scales formed in molten (Ns, K)2 SO4 NaCl. Enamel coating can effectively protect Ti-24Al-17Nb-0.5Mo alloy from long-term oxidation at high temperature in air and remarkably improve the hot corrosion resistance of Ti-24Al-17Nb-0. 5Mo alloy, and can act as the barrier to suppress the migration of oxygen and corrosive ions into the substrate.     

低弹性模量Ti-27Nb-8Zr医用钛合金组织与力学性能

利用光学显微镜、扫描电镜和X射线衍射仪研究Ti-27Nb-8Zr(质量分数, %)医用钛合金固溶后在不同时效温度下组织的变化规律,重点讨论不同显微组织对合金弹性模量和强度的影响。结果表明,固溶处理后,合金组织由β+α”两相构成,具有相对低的弹性模量和强度;时效后,组织中包含β、α、ω三相,弹性模量和强度显著升高,随着时效温度的升高,组织长大,弹性模量和强度降低     

SiCf/Ti-22Al-23Nb-2Ta合金复合材料的界面微结构

利用分析电子显微镜（AEM）研究了磁控溅射法＋真空热压方法制备的SiC纤维增强Ti-22Al—23Nb-2Ta（原子分数,％）合金复合材料的界面微结构．该复合材料的纤维／合金界面由细晶粒的TiC＋TiSi层、等轴晶TiC层和（Al,Ti）Nb2相层组成．界面的形成主要是基体合金中的Ti元素与SiC纤维表面的C涂层直接反应生成TiC;同时导致在次层形成贫Ti层和贫Ti层中Nb元素富集,以致形成（Al,Ti）Nb2相．     

Ti-15Mo-3Al-2.7Nb-0.2Si钛合金绝热剪切带的微观结构演化

采用分离式Hopkinson压杆技术对Ti-15Mo-3Al-2.7Nb-0.2Si钛合金的帽形试样进行了强迫剪切试验,通过扫描电镜(SEM)及透射电镜(TEM)研究了Ti-15Mo-3Al-2.7Nb-0.2Si钛合金在动态加载下绝热剪切带的微观结构演化.结果表明:Ti-15Mo-3Al-2.7Nb-0.2Si钛合金由于其组织以bee晶格的a相为主,具有较好的变形能力,因此其绝热剪切带的形成是位错运动的结果;剪切带的微观结构演化过程为:晶粒在外加切应力作用下拉长变形一拉长晶粒的破碎-形成呈一定方向排列的细小等轴晶:带内形成的细小等轴晶尺寸为O.2～0.4ìm.