Porous Ti not only inherits the physical and chemical properties of titanium alloy, such as higher special stiffness, special strength, excellent corrosion resistance and biocompatibility, but also its unique pore structure gives it the characteristic of ultra-low density and large surface area. It is an alternative material for human body with structural and functional integration. It has been widely used in the field of clinical medicien in recent years. Many research and applications show that the properties and functions of porous Ti strongly depend on the pore structure of porous Ti prepared by different methods. Surface activation technology can significantly improve the surface activity of porous Ti and shorten the healing period after implantation. In this paper the common preparation methods of porous Ti were introduced based on the structure and properties of porous Ti. The surface modification, biological activity, osteoinductive properties of porous Ti and their domestic research status were summrized. The development of biomedical porous Ti and titanium alloys was prospected.

多孔Ti继承了钛合金较高的比刚度、比强度等物理化学特性、优异的耐腐蚀性和生物相容性,其独特的孔隙结构又赋予其超低密度和大比表面积等特点,是结构功能一体化的人体替代材料,近年来在临床医学领域得到了非常广泛的应用。众多研究和应用表明,多孔Ti的性能和功能强烈依赖于不同方法制备多孔Ti的孔隙结构。表面活化技术可显著提高多孔Ti的表面活性,缩短植入人体后的愈合期。本文针对多孔Ti的结构和性能特点,介绍了多孔Ti的常见制备方法,对多孔Ti的表面改性、生物活性与骨诱导性及国内的研究现状进行了总结,展望了生物医用多孔Ti及钛合金的发展。

An experimental investigation was undertaken to measure the intrinsic elastic properties of several of the microstructural components of human vertebral trabecular bone and tibial cortical bone by the nanoindentation method. Specimens from two thoracic vertebrae (T-12) and two tibiae were obtained from frozen, unembalmed human male cadavers aged 57 and 61 years. After drying and mounting in epoxy resin nanoindentation tests were conducted to measure Young's modulus and the hardness of individual trabeculae in the vertebrae and single osteons, and interstitial lamellae in the tibiae. Measurements on the vertebral trabeculae were made in the transverse direction, and the average Young's modulus was found to be 13.5 +/- 2.0 GPa. The tibial specimens were tested in the longitudinal direction, yielding moduli of 22.5 +/- 1.3 GPa for the osteons and 25.8 +/- 0.7 GPa for the interstitial lamellae. Analysis of variance showed that the differences in the measured moduli are statistically significant. Hardness differences among the various microstructural components were also observed.

In this paper, the elastic deformation behaviour of a recently developed beta-type titanium alloy Ti-24Nb-4Zr-7.9Sn (wt.%) that consists of non-toxic elements and is intended for biomedical applications is described. Tensile tests show that this alloy in the as hot-rolled state exhibits peculiar non-linear elastic behaviour with maximum recoverable strain up to 3.3% and incipient Young's modulus of 42GPa. Solution treatment at high temperature has trivial effect on super-elasticity but decreases strength and slightly increases the incipient Young's modulus. Ageing treatment in the (alpha+beta) two-phase field increases both strength and Young's modulus and results in a combination of high strength and relatively low elastic modulus. In spite of the formation of the alpha phase, short time ageing has no effect on super-elasticity, whereas the non-linear elastic behaviour transforms gradually to normal linear elasticity with the increase of ageing time. We suggest sluggish, partially reversible processes of stress-induced phase transformation and/or incipient kink bands as the origin of the above peculiar elastic behaviour.

Titanium and titanium alloys have widely been used in biomedical applications as main substitutes for hard human tissues. To better meet the needs of safety, comfort, and durability of titanium and titanium alloys after implantation in the human body, the surface modification treatment of titanium and titanium alloys has become a research hotspot. In this review, based on the basic properties and existing problems of titanium and titanium alloys, the methods of surface modification for titanium and titanium alloys are introduced to improve their mechanical properties, biocompatibility, and bacteriostatic/antibacterial properties. Furthermore, the current challenges and prospects have been presented in this paper.

Ti及钛合金作为人体硬组织的主要替代物之一,在生物医用领域应用广泛。为了更好地满足Ti及钛合金在人体中植入后的安全、舒适、耐久等需求,Ti及钛合金表面改性处理成为了研究的热点。本文基于Ti及钛合金的基础性能和存在的问题,从表面改性提高其力学性能、生物相容性、抑菌/抗菌性能等方面综述了Ti及钛合金表面改性在生物医用领域的研究进展,并提出了面临的挑战以及发展方向的建议。

The present work formulated a materials design approach, a cluster-formula-embedded machine learning (ML) model, to search for body-centered-cubic (BCC) β-Ti alloys with low Young’s modulus (E) in the Ti–Mo–Nb–Zr–Sn–Ta system. The characteristic parameters, including the Mo equivalence and the cluster-formula approach, are implemented into the ML to ensure the accuracy of prediction, in which the former parameter represents the BCC-β structural stability, and the latter reflects the interactions among elements expressed with a composition formula. Both auxiliary gradient-boosting regression tree and genetic algorithm methods were adopted to deal with the optimization problem in the ML model. This cluster-formula-embedded ML can not only predict alloy property in the forward design, but also design and optimize alloy compositions with desired properties in multicomponent systems efficiently and accurately. By setting different objective functions, several new β-Ti alloys with either the lowest E (E = 48 GPa) or a specific E (E = 55 and 60 GPa) were predicted by ML and then validated by a series of experiments, including the microstructural characterization and mechanical measurements. It could be found that the experimentally obtained E of predicted alloys by ML could reach the desired objective E, which indicates that the cluster-formula-embedded ML model can make the prediction and optimization of composition and property more accurate, effective, and controllable.

<p>Biomedical titanium alloy materials have become the main raw materials for orthopedic, dental and cardiovascular implants or devices, but their biological and mechanical compatibility remains to be improved to meet the long-term safety and function in services for clinical application. Whether developing the novel medical titanium alloys with high-strength, low-modulus and other finer comprehensive performance, or upgrading and optimizing the traditional medical titanium alloys, it is the foundation and key to ensuring the structure homogeneity, high performance, versatility and low cost of biomedical titanium alloy materials and expanding its clinical application. The design, physical metallurgy, materials process, microstructure and properties, surface modification, advanced manufacturing and the clinical application of biomedical titanium alloys were introduced, and their latest research progress was reviewed in this paper, together with the recent advances in the author's R & D team. Finally, the further research and development trend of biomedical titanium alloys are summarized.</p>

医用钛合金材料已成为骨科、齿科和心血管等植介入物或器械用主要原材料,但要满足患者临床治疗的长效安全性和功能性,医用钛合金材料的生物及力学相容性仍有待提高。无论是开发新型高强度、低模量等综合性能优良的新型医用钛合金材料,还是立足对传统医用钛合金材料性能的优化升级,确保医用钛合金材料的均质化、高性能、多功能和低成本是扩大其临床应用的基础和关键。本文从医用钛合金材料合金设计、物理冶金、材料加工、组织与性能、表面改性、先进制造及临床应用等诸方面进行综述,并介绍了作者研发团队的最新进展,展望了未来发展趋势及待解决的问题。

利用激光熔化沉积技术(LMD)增材制造了具有单相bcc结构的Al_0.21Co_0.17Cr_0.13Fe_0.11Ni_0.18Si_0.20 (原子分数)高熵合金(HEA)，其晶粒尺寸随着激光功率从900 W降低至700 W而逐步减小。在1100 ℃“干”空气和含10%H₂O (体积分数)的“湿”空气的恒温氧化实验表明：该HEA能稳定生长单一的Al₂O₃膜；晶粒尺寸减小导致所生长Al₂O₃膜的氧化速度降低；H₂O蒸气加快Al₂O₃膜生长速度。

轻质耐热的TiAl合金是航空航天和民用工业等领域最具潜力的高温结构材料之一。然而，由于其低的延展性和断裂韧性，制造TiAl零部件具有挑战性。目前，增材制造工艺被认为是制造TiAl零件具有前途的技术之一。本文在介绍增材制造技术原理和特点的基础上，综述了激光金属沉积(LMD)、选区激光熔化(SLM)和电子束熔化(EBM)制备TiAl合金的工艺-组织-性能关系，并对该技术未来的发展趋势进行了展望。

Electron beam melting (EBM) is one of the additive manufacturing technologies which can be used to fabricate the complex structure and shape samples. Until now, there are few literatures published about the properties of Ti-Ni samples produced by EBM. In this work, the influence of two important manufacturing parameters of focus offset (FO) and speed function (SF) on the density, phase content and transformation behavior, microstructure and mechanical properties was investigated for the equiatomic Ti-Ni shape memory alloy fabricated by EBM used DSC, XRD, SEM, TEM and electronic universal testing machine. The results showed that all the Ti-Ni samples had a high relative density beyond than 97% for fabricated by different combinations of FO and SF in the selected range. The corresponding phase transformation temperatures for all the Ti-Ni samples fabricated by EBM were higher than the pre-alloyed Ti-Ni powder, due to the effect of evaporation of Ni element higher than that of the formation of Ni-rich Ti2Ni phase during the quickly melting and solidification process. On the other hand, the EBM manufacturing parameters of FO and SF had limited influence on the phase contents, phase transformation temperatures and Vickers hardness. Due to the feature of the EBM fabricating method, the different types of defects would be introduced in the Ti-Ni solid samples. Though all the samples had similar high relative density, the performance of the compression behavior were shown great difference, and the crack defect had the larger effect than the gas and lack-of fusion porosities on the compression fracture stress and strain.

利用SEM、XRD、DSC、TEM和等轴压缩等实验手段，研究和分析了打印参数焦距补偿(FO)和速度函数(SF)对电子束增材制造(EBM)制备的Ti-Ni合金显微组织、相组成、相变行为以及压缩性能的影响。结果表明：EBM打印参数FO和SF在一定范围内调节时均可制备出相对密度较高(97%以上)的Ti-Ni合金样品。由于EBM电子束的功率大，在预合金粉末快速受热熔化过程中，Ni元素的挥发效应大于富Ti相Ti₂Ni析出效应对相变温度的影响，使得制备Ti-Ni块体的相变温度大于相应的预合金粉末，而打印参数FO和SF对制备样品的相变温度、相组成以及显微硬度的影响较小。EBM制备过程中在样品内部引入不同种类的缺陷类型，使得Ti-Ni合金样品在相对密度接近的情况下压缩性能表现出极大的差异，其中贯穿型裂纹缺陷对压缩性能的影响最大，使Ti-Ni合金的强度和塑性大幅度降低。

Evaluation of the high-temperature tensile properties of Ti-6Al-4V manufactured by electron beam melting (EBM) and subjected to a low-temperature hot isostatic pressing (HIP) treatment (800 °C) was performed in this study. The high-temperature tensile properties of as-built and standard HIP-treated (920 °C) materials were studied for comparison. Metallurgical characterization of the as-built, HIP-treated materials was carried out to understand the effect of temperature on the microstructure. As the HIP treatments were performed below the β-transus temperature (995 °C for Ti-6Al-4V), no significant difference was observed in β grain width between the as-built and HIP-treated samples. The standard HIP-treated material measured about 1.4×–1.7× wider α laths than those in the modified HIP (low-temperature HIP)-treated and as-built samples. The standard HIP-treated material showed about a 10–14% lower yield strength than other tested materials. At 350 °C, the yield strength decreased to about 65% compared to the room-temperature strength for all tested specimens. An increase in ductility was observed at 150 °C compared to that at room temperature, but the values decreased between 150 and 350 °C because of the activation of different slip systems.

The powder metallurgy method was used to manufacture three Ti-based alloys: Ti-15%Zr-2%Ta-4%Sn (Ti-Zr-Ta-4Sn), Ti-15%Zr-2%Ta-6%Sn (Ti-Zr-Ta-6Sn), and Ti-15%Zr-2%Ta-8%Sn (Ti-Zr-Ta-8Sn). Electrochemical measurements and surface analyses were used to determine the effect of Sn concentration on the corrosion of these alloys after exposure to a simulated body fluid (SBF) solution for 1 h and 72 h. It was found that the passivation of the alloy surface significantly increased when the Sn content increased from 4% to 6% and then to 8%, which led to a significant reduction in corrosion. The impedance spectra derived from the Nyquist graphs also explained how the addition of Sn significantly improved the alloys’ polarization resistances. According to the change in the chronoamperometric current at an applied anodic potential over time, the increase in Sn content within the alloy significantly reduced the currents over time, indicating that the uniform and pitting corrosion were greatly decreased. The formation of an oxide layer (TiO2), which was demonstrated by the surface morphology of the alloys after exposure to SBF solution for 72 h and corrosion at 400 mV (Ag/AgCl) for 60 min, was supported by the profile analysis obtained by an X-ray spectroscopy analyzer. It was clear from all of the findings that the tested alloys have a remarkable improvement in resistance to corrosivity when the Sn content was increased to 8%.

研究选区激光熔化(Selective laser melting，SLM) Ti6Al4V合金的成型方向及热处理对其在Hanks体液中腐蚀性能的影响。针对不同状态SLM-Ti6Al4V合金的微观组织结构，借助电化学方法跟踪其在Hanks体液中的腐蚀钝化行为，从α/α′相含量、尺寸和取向分布等因素揭示不同状态合金在医用环境中耐腐蚀性能差异的机理。结果表明，成型方向和后续热处理对SLM-Ti6Al4V合金微观组织结构的影响导致了其腐蚀行为的差异。800 ℃以下热处理合金的XZ面耐腐蚀性优于XY面，表现出明显的各向异性，且随热处理温度的升高α/α′相尺寸增大，耐腐蚀性逐渐下降，各向异性减弱。800 ℃及以下热处理SLM-Ti6Al4V合金的腐蚀以点蚀为主，900 ℃及以上热处理合金的腐蚀机制为沿晶界腐蚀。800 ℃热处理合金的α/α′相尺寸及界面密度与成型态相当，表现出良好的耐腐蚀能力。

Metastable β titanium alloys, such as Ti-24Nb-4Zr-8Sn, have potential for application in vibration damping systems due to their ability to display superelastic behaviour. However, their use is currently limited due to large variations in the temperature range over which this behaviour is stable, which can additionally be shown to depend on the thermal history of the sample. This study demonstrates the sensitivity of the microstructure to thermal history and highlights a possible cause for this variability. Currently held theories of ω formation supressing the martensitic transformation have been called into question and an alternative mechanism based on a total stress approach has been suggested. Understanding this variability enables better design of alloys and processing routes in order to achieve materials with the desired properties required for industrial application.

The link and difference between orthorhombic phase transformations in&nbsp;<em>&beta;</em>-type titanium alloys and in Ti₃Al containing high concentrations of transition metal elements such as Nb are first outlined in this paper. Recent investigations on these transformations conducted in the authors' group are reviewed followed by discussions of remaining problems. Three examples were presented to illustrate the applications of the orthorhombic phase transformations: design and development of superelastic titanium alloys for biomedical use, preparation of ultra-fine basketweave microstructure of titanium alloy wire for fastener manufacturing, and sheet and foil production of alloys based on Ti₂AlNb.

4D打印技术自2013年提出以来就引起了学术和工业界的广泛关注，它属于智能构件的增材制造技术，是在材料、机械、力学、信息等学科高度交叉融合基础上产生的颠覆性制造技术。讨论了4D打印的概念与内涵；介绍了4D打印在航空航天、汽车、生物医疗和软体机器人等领域的应用前景；阐述了4D打印在智能构件设计、模拟仿真、数据处理与工艺规划、材料、成形工艺与装备和智能构件的功能评测等方面的发展现状以及目前存在的一些问题；提出了关于4D打印的研究思考，最后指出了4D打印的未来发展方向和研究重点。

研究了多功能亚稳&beta;型Ti2448(Ti-24Nb-4Zr-8Sn, 质量分数, %)合金在$\beta$单相区的高温变形行为. 结果表明,在低应变速率(-1</sup>)和高应变速率(>1 s^-1)条件下, 真应力和应变速率的双对数关系可以通过2个线性关系分别表征, 平均应变速率敏感值(m_avg)分别为0.265和0.032, 这不同于常规&beta;钛合金随着应变速率的增大而逐渐降低的应变硬化规律, 即Sigmoidal曲线特征. 微观组织演化和动力学分析显示, 这种特殊的双线性关系与高应变速率导致的局域化非均匀塑性变形行为和动态再结晶(DRX) 相关联.尽管动态回复(DRV)是该合金高温塑性变形的主要组织演变机制, 高应变速率使得组织演变从DRV向DRX 转变, 并在交错的变形带内形成小于3&nbsp;&mu;m的细晶组织. 因此, 高应变速率条件下的DRX是实现Ti2448合金高温变形过程中细化组织的主要机制.

基于热锻/热轧工艺以及均匀化热处理制备了孪生与位错滑移耦合变形的Ti-10Mo-1Fe/3Fe层状合金，利用LSCM、XRD、SEM、SEM-EDS、EBSD、Vickers硬度计和拉伸试验机等研究了预变形与等温时效耦合作用对层状合金力学性能的影响。结果表明，经拉伸预变形和等温时效处理后，该合金具有{332}&lt;113&gt;孪晶和位错滑移带多层交替变形组织，且呈现出较高的屈服强度和较大的均匀伸长率。等温时效析出的ω相提高了β相稳定性，使得变形初期的塑性变形方式由位错滑移主导，这是其具有较高屈服强度的主要原因。预变形诱发的孪晶推迟了屈服之后颈缩的快速发生，而且后续变形过程中进一步激活的孪晶引起的动态晶粒细化效应及其与层界面的交互作用，使其具有较大的均匀伸长率。因此，在孪生与位错滑移耦合变形层状合金的基础上，进一步通过预变形诱发{332}&lt;113&gt;孪晶和等温时效析出ω相的双重耦合效应，可在较大范围内调控β型钛合金的强塑性匹配。

针对TiAl合金在热循环环境中的抗氧化需求，本文采用电沉积方法在TiAl合金表面制备了SiO₂涂层，并研究了涂层在900 ℃下的抗循环氧化性能，分析了电沉积SiO₂涂层的失效机制。实验结果表明，电沉积SiO₂涂层可有效提高TiAl合金的抗循环氧化性能。SiO₂涂层可与TiAl基体发生反应生成 Ti₅Si₃，促进界面处选择性氧化生成Al₂O₃层，起到扩散阻挡作用。然而，由于SiO₂涂层与TiAl合金存在热失配问题，会导致涂层内热应力集中，从而萌生裂纹。裂纹为氧的向内扩散和基体元素的向外扩散提供了通道，在氧化膜表面形成大量团簇，导致了SiO₂涂层连续致密的结构遭到破坏，但SiO₂涂层循环氧化200 h后仍未发生剥落，说明其仍保持一定的高温防护能力。

利用双阴极等离子溅射技术在Ti-6Al-4V (TC4) 合金表面沉积Nb涂层，采用XRD、XPS和SEM研究涂层的组成及横截面形貌，并采用电化学工作站对涂层与基体的电化学性能及其钝化膜半导体特性进行研究。电化学测试均在模拟人体体液环境的Ringer's溶液中37 ℃下进行。结果表明，Nb涂层厚度约为18 μm，无孔洞、裂纹等缺陷，在 (200) 晶面呈现择优取向。涂层表面钝化膜成分主要为Nb₂O₅。相比TC4基体，涂层具有更高的开路电位E_OCP、腐蚀电位E_corr和更低的腐蚀电流密度I_corr；涂层与基体合金试样均表现出单一容抗弧，但涂层具有更高的阻抗和较低的有效电容值；两种试样的钝化膜均表现出n型半导体特性，在不同的成膜电位E_f下，Nb涂层的钝化膜具有更低的平带电位E_fb，施主密度N_d和扩散系数D₀。