超重力场反应连接制备TiB_2-TiC/1Cr18Ni9Ti和TiB_2-TiC/Ti-6Al-4V梯度复合材料

以1Cr18Ni9Ti、Ti-6Al-4V为金属基底,通过在B4C+Ti体系中引入CrO_3+Al铝热剂,调整反应体系绝热温度依次为3 193、3 282、3 290及3 473K,采用超重力场反应连接制备TiB_2-TiC/1Cr18Ni9Ti和TiB_2-TiC/Ti-6Al-4V梯度复合材料,发现随着反应绝热温度升高,陶瓷/金属界面区厚度不仅因金属熔深增加而增大,并且残存于界面上的Al_2O_3夹杂也随之增多。分别对B4C+Al体系与CrO_3+Al铝热剂进行配制、球磨活化、压制成坯并依次填料入坩埚后,发现残存于界面上的Al_2O_3夹杂完全消除,同时发现在TiB_2-TiC/1Cr18Ni9Ti界面上生成三维网络陶瓷/金属梯度复合结构,而在TiB_2-TiC/Ti-6Al-4V界面上形成跨尺度多层次梯度复合结构。     

Surface characteristics of a porous-surfaced Ti-6Al-4V implant fabricated by electro-discharge-compaction

Electro-discharge-compaction (EDC) is a unique method for producing porous-surfaced metallic implants. The objective of the present studies was to examine the surface characteristics of the Ti-6Al-4V implants formed by EDC. Porous-surfaced Ti-6Al-4V implants were produced by employing EDC using 480 F capacitance and 1.5 kJ input energy. X-ray photoelectron spectroscopy was used to study the surface characteristics of the implant materials. C, O, and Ti were the main constituents, with smaller amounts of Al and V. EDC Ti-6Al-4V also contained N. Titanium was present mainly in the forms of mixed oxides and small amounts of nitride and carbide were observed. Al was present in the form of aluminum oxide, while V in the implant surface did not contribute to the formation of the surface oxide film. The surface of conventionally prepared Ti-6Al-4V primarily consists of TiO₂, whereas, the surface of the EDC-fabricated Ti-6Al-4V consists of complex Ti and Al oxides as well as small amounts of titanium carbide and nitride components. However, preliminary studies indicated that the implant was biocompatible and supports rapid osseointegration.     

Interface contribution to the SiC-titanium and SiC-aluminium tensile strength prediction

Fragmentation tests of single SiC filaments embedded in an aluminium (1050 and 5083 alloys) or a titanium (Ti-6Al-4V) matrix have been analysed in an effort to obtain the interface contribution in terms that could be incorporated into a tensile fracture model for unidirectional composites. Depending on the matrix, two regimes of interfacial stress transfer can be distinguished within the whole range of tested temperatures. For the SCS2/5083 system, plastic deformation of the alloy limits the stress transfer, and the interface contribution thus finds its expression in the shear stress of the matrix. for the SCS6/Ti-6Al-4V system, friction is the leading process and the interface contribution strongly depends on the stress state around the fibre. Assuming a temperature dependent compressive radial stress up to 925C, an effective transfer shear stress may be easily calculated for unidirectional SCS6/Ti-6Al-4V composites.     

Untersuchungen zur Eignung von ionenplattierten metallischen Schutzschichten auf Ti-6Al-4V bei Schwingungsverschleißbeanspruchung

Investigations on the Suitability of lon-Plated Metallic Coatings on Ti-6Al-4V at Fretting Fatigue Load To provide fretting fatigue damage flat specimens of the alloy Ti-6Al-4V were supplied with metallic coatings. For that purpose specimens were coated with Cu, Cr, V, Ti and with an Al/Cu-combination. These coated specimens were then tested in a fretting bridge equipment. It was found that all coatings except the Al/Cu-combination lead to considerable improvement of fretting fatigue life. As SEM-investigations show, a separation of the functions of specimen-body and specimen-surface was achieved by the coatings, so that the effectiveness of coatings of rather low wear-resistance is explicable.     

Fabrication of TiC/TiB/Ti3AlC2 phases reinforced coatings on Ti-6Al-4V substrate

Intermetallic matrix composite coatings reinforced by TiC, TiB₂, and Ti₃AlC₂ were fabricated by laser cladding the mixed power Ti, Al, and B₄C on the Ti-6Al-4V alloy. X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy were chosen to investigate the structures and morphologies of the coatings. Results showed that the coatings mainly consisted of the reinforcements of TiC, TiB₂, and Ti₃AlC₂ and the matrix of Ti₃Al, TiAl, TiAl₃, and α-Ti. The hardness and wear-resisting property of the prepared specimens of Ti-45Al-10B₄C and Ti-45Al-20B₄C were studied contrastively. It was found that the coating was metallurgical bonded to the Ti-6Al-4V substrate. The micro-hardness and dry sliding wear-resisting properties of the specimen of Ti-45Al-20B₄C were enhanced further. And the micro-hardness of Ti-45Al-20B₄C was from 900 HV_0.2 to 1225 HV_0.2. The wear-resisting property of Ti-45Al-20B₄C was four times as large as that of the Ti-6Al-4V alloys.     

Spine rod straightening as a possible cause for revision

In a previous study, the authors examined the elastic and short-term anelastic springback of Ti6Al4V, CoCrMoC and A316L stainless steel spine rods to observe how the rods mechanically respond in OR contouring. In that study rods were 200?mm long and only the movement at the tip was recorded. The implication of that work was that rods will straighten in-vivo, however, in order for the mechanism of straightening to be determined, the movement of individual bends over time must first be elucidated. Spine rods used were, commercially pure titanium (CP Ti) a primarily α-phase; Ti-6Al-4V; α/β-phase titanium alloy from two different suppliers (denoted by, Ti-6Al-4V (L) and Ti-6Al-4V); β-phase titanium (TNTZ) and CoCrMoC. Following contouring the rods were aged unconstrained, in normal atmosphere or simulated body fluid (SBF) in a CO₂ incubator for up to 288?h. Elastic springback is significantly different between alloys with different microstructures. Both types of Ti6Al4V rods, while meeting the ASTM F136 industry standard, have significantly different properties, most importantly yield strength, flexural modulus, and springback. Environment showed no significant impact on anelasticity. The anelastic response of Ti6Al4V L sample, which has relatively more beta phase than the Ti6Al4V sample, follows the pure beta phase TNTZ in its extended time response. CoCrMoC and CP Ti have a very reduced anelastic response compared to the other alloys. This potentially can have unanticipated effects on the outcome of spine procedures, as the surgeon is reliant on the rods having similar properties to achieve a desired outcome.     

Effect of sputtered TiAlCr coatings on oxidation and hot corrosion resistance of Ti-24Al-14Nb-3V

The effect of sputtered Ti-50Al-10Cr and Ti-50Al-20Cr coatings on both isothermal and cyclic oxidation resistance at 800 similar to 900 degreesC and hot corrosion resistance at 850 degreesC of Ti-24Al-14Nb-3V was investigated. Results indicated that Ti-24Al-14Nb-3V alloys exhibited poor oxidation resistance due to the formation of Al2O3+TiO2+AlNbO4 mixed scales in air at 800 similar to 900 degreesC and poor hot corrosion resistance due to the spallation of scales formed in Na2SO4+K2SO4 melts at 850 degreesC. Both Ti-50Al-10Cr and Ti-50Al-20Cr coatings remarkably improved the oxidation and hot corrosion resistance of Ti-24Al-14Nb-3V alloy.     

Improved properties of Ti-6Al-4V by combining isothermal equal-channel angular processing and hot-extrusion

The aim of this work was to study effects of hot extrusion on the microstructure of Ti-6Al-4V (wt-%) alloy processed by ECAP. Firstly, an isothermally Ti–6Al–4V alloy processed by Equal channel angular pressing(ECAP) was preheated at 950°C for 6?min and then hot extruded at 900°C. The hot extrusion minimised the grain size and maximised the mechanical strength. Therefore, it was demonstrated that hot extrusion of Ti-6Al-4V alloys that processed by ECAP could be performed without compromising any mechanical properties. Therefore, it is possible to use the ability to apply a reduced cross-section in hot extrusion for an Ti-6Al-4V processed by ECAP without concern about the reduction of properties.     

3D打印医用钛合金的抗菌性能和体外生物相容性

应用选择性激光熔融技术(SLM)制备出3D打印医用钛合金Ti-6Al-4V和Ti-6Al-4V-5Cu,用平板共培养法研究测定其抗菌性能,用CCK8细胞增殖测定法、鬼笔环肽细胞骨架染色法和Annexin-V/PI流式细胞术研究了这种合金的抗菌性能和对小鼠胚胎成骨前体细胞(MC3T3-E1)的体外生物相容性影响。结果表明,3D打印Ti-6Al-4V-5Cu合金具有较高的抗菌性能,对金黄色葡萄球菌的抗菌率达到(57.03±1.55)%。在CCK8细胞增殖毒性测定、细胞骨架鬼笔环肽染色实验和Annexin-V/PI双标记法流式分析三种研究中Ti-6Al-4V-5Cu表现的优越,具有更好的体外生物相容性。     

Fibroblast Adhesion and Proliferation on a New β Type Ti-39Nb-13Ta-4.6Zr Alloy for Biomedical Application

Cell attachment and spreading on Ti-based alloy surfaces is a major parameter in implant technology. Ti39Nb-13Ta-4.6Zr alloy is a new β type Ti alloy developed for biomedical application. This alloy has low modulus and high strength, which indicates that it can be used for medical purposes such as surgical implants.To evaluate the biocompatibility and effects of the surface morphology of Ti-39Nb-13Ta-4.6Zr on the cellular behaviour, the adhesion and proliferation of rat gingival fibroblasts were studied with substrates having different surface roughness and the results were also compared with commercial pure titanium and Ti-6Al-4V. The results indicate that fibroblast shows similar adhesion and proliferation on the smooth surfaces of commercial pure titanium (Cp Ti), Ti-39Nb-13Ta-4.6Zr, and Ti-6Al-4V, suggesting that Ti-39Nb-13Ta-4.6Zr has similar biocompatibility to Cp Ti and Ti-6Al-4V. The fibroblast adhesion and spreading was lower on rough surfaces of Cp Ti, Ti-39Nb-13Ta-4.6Zr and Ti-6Al-4V than on smooth ones. Surface roughness appeared to be a dominant factor that determines the fibroblast adhesion and proliferation.     

Fibroblast Adhesion and Proliferation on a New β Type Ti-39Nb-13Ta-4.6Zr Alloy for Biomedical Application

Cell attachment and spreading on Ti-based alloy surfaces is a major parameter in implant technology. Ti-39Nb-13Ta-4.6Zr alloy is a new β type Ti alloy developed for biomedical application. This alloy has low modulus and high strength, which indicates that it can be used for medical purposes such as surgical implants. To evaluate the biocompatibility and effects of the surface morphology of Ti-39Nb-13Ta-4.6Zr on the cellular behaviour, the adhesion and proliferation of rat gingival fibroblasts were studied with substrates having different surface roughness and the results were also compared with commercial pure titanium and Ti-6Al-4V. The results indicate that fibroblast shows similar adhesion and proliferation on the smooth surfaces of commercial pure titanium （Cp Ti）, Ti-39Nb-13Ta-4.6Zr, and Ti-6Al-4V, suggesting that Ti-39Nb-13Ta-4.6Zr has similar biocompatibility to Cp Ti and Ti-6Al-4V. The fibroblast adhesion and spreading was lower on rough surfaces of Cp Ti, Ti-39Nb-13Ta-4.6Zr and Ti-6Al-4V than on smooth ones. Surface roughness appeared to be a dominant factor that determines the fibroblast adhesion and proliferation.     

The microstructural observation and wettability study of brazing Ti-6Al-4V and 304 stainless steel using three braze alloys

Both Ti-6Al-4V and 304 stainless steels (304SS) are good engineering alloys and widely used in industry due to their excellent mechanical properties as well as corrosion resistance. Well-developed joining process can not only promote the application of these alloys, but also can provide designers versatile choices of alloys. Brazing is one of the most popular methods in joining dissimilar alloys. In this study, three-selected silver base filler alloys, including Braze 580, BAg-8 and Ticusil®, are used in vacuum brazing of 304SS and Ti-6Al-4V. Based upon dynamic sessile drop test, Braze 580 has the lowest brazing temperature of 840°C, in contrast to 870°C for BAg-8 and 900°C for Ticusil® braze alloy. No phase separation is observed for all brazes on 304SS substrate. However, phase separation is observed for all specimens brazed above 860°C on Ti-6Al-4V substrate. The continuous reaction layer between Braze 580 and 304SS is mainly comprised of Ti, Fe and Cu. The thickness of reaction layer at Braze 580/Ti-6Al-4V interface is much larger than that at Braze 580/304SS interface. Meanwhile, a continuous Cu-Sn-Ti ternary intermetallic compound is found at the Braze 580/Ti-6Al-4V interface. Both Ticusil® and BAg-8 brazed joint have similar interfacial microstructures. Different from the Braze 580 specimen, there is a thick Cu-Ti-Fe reaction layer in both BAg-8/304SS and Ticusil®/304SS interfaces. The formation of Cu-Ti-Fe interfacial layer can prohibit wetting of BAg-8 and Ticusil® molten brazes on 304SS substrate. Meanwhile, continuous Ti₂Cu and TiCu layers are observed in Ti-6Al-4V/BAg-8 and Ti-6Al-4V/Ticusil® interfaces.     

Plain fatigue and fretting fatigue behaviour of plasma nitrided Ti-6Al-4V

Fatigue tests with and without fretting against unnitrided fretting pads were conducted on unnitrided and plasma nitrided Ti-6Al-4V samples. Plasma nitrided samples exhibited higher surface hardness, higher surface compressive residual stress, lower surface roughness and reduced friction force compared with the unnitrided specimens. Plasma nitriding enhanced the lives of Ti-6Al-4V specimens under both plain fatigue and fretting fatigue loadings. This was explained in terms of the differences in surface hardness, surface residual stress, surface roughness and friction force between the unnitrided and nitrided samples.     

Formation of a crack-free joint between Ti alloyand Al alloy by using a high-power CO2 laser

The present paper aims at producing a crack-free weld between a commercially available Ti alloy (Ti-6 wt% Al-4 wt% V) and a wrought Al alloy (Al-1 wt% Mg-0.9 wt% Si). Ti alloy and Al alloy with a plate thickness of 3 mm are butt welded using a 2.5 kW continuous CO2 laser. The laser power, welding speeds and offset of the laser with respect to the joint are considered as the variable parameters. It is observed that intermetallic compounds (mainly TiAl and Ti3Al) are formed in the fusion zone depending on the amount of Al and Ti melted by the laser. These intermetallic phases are very brittle and the solid-state cracks are formed near the Al side of the interface because of the stress developed after the solidification. The formation of cracks is sensitive to the total Al content in the fusion zone. In order to minimize the dissolution of Al in the fusion zone and to increase the toughness of the intermetallic phases, Nb foil is added as a buffer between the Ti alloy and Al alloy workpieces. It is observed that the partially melted Nb acts as a barrier to dissolve Al in the fusion zone and facilitates a good joining condition for welding of Ti alloy with Al alloy. This revised version was published online in November 2006 with corrections to the Cover Date.     

氢对Ti-6Al-4V合金室温压缩性能的影响

为了研究氢对Ti-6Al-4V合金室温压缩性能的影响,采用Zwick/Z100型材料试验机对置氢Ti-6Al-4V合金进行了压缩试验,并利用OM、XRD和TEM等材料分析方法对合金的微观组织进行了观察.研究表明:置氢前,Ti-6Al-4V合金由等轴的α相和β相组成,置氢后,出现马氏体组织和氢化物;随氢含量增加,马氏体和剩余β相数量增多;氢提高了Ti-6Al-4V合金的抗压强度和塑性等室温压缩性能,最大增幅分别为33.9%和56.3%;置氢Ti-6Al-4V合金抗压强度的提高主要归因于氢的固溶强化、马氏体相变强化和氢化物强化;塑性指标的提高主要是置氢合金中塑性β相数量的增多所致.     

In situ synthesis of TiB whisker reinforcements in the joints of Al2O3/TC4 during brazing

Al₂O₃ ceramic has been successfully joined to Ti-6Al-4V alloy with Ag-Cu-Ti-B mixed powder. The TiB whiskers in the brazing layer were in situ synthesized during brazing. The effects of B content in reactant on the phase composition, microstructure and shear strength of the joints were investigated using SEM, EDS, and shear test. Results indicate that B content in the filler has a great impact upon the microstructure of the joints via exerting an influence on the volume fraction of in situ synthesized TiB whiskers. When the TiB content is 40 vol.%, the shear strength reaches the maximum value of 77.9 MPa. The higher content of TiB (≥40 vol.%) depresses the shear strength of the joints due to the interfacial thermal stress cannot be relaxed. Reaction phases (Ti₃Cu₂AlO, Ti₂Cu, Ti₂(Cu, Al), Ti(Cu, Al) and Ti₃Al) appear in the joint, moreover, as the volume fraction of TiB increase, Ag (s.s) and Ti(Cu, Al) distribute more uniform and fine in the brazing layer, as well as TiB whiskers mainly distribute in them. Eventually, Ti₃Cu₂AlO, TiB and TiB₂ firstly generate based on the thermodynamic analysis, and in excessive Ti circumstances, TiB whiskers remain in the brazing alloy.     

Joining of Zirconia and Ti-6Al-4V Using a Ti-based Amorphous Filler

Polycrystalline ZrO2-3 mol.%Y2O3 was brazed to Ti-6Al-4V by using a Ti47Zr28Cu14Ni11(at.%) amorphous ribbon at 1123-1273 K in a high vacuum. The influences of brazing temperature on the microstructure and shear strength of the joints were investigated. The interfacial microstructures can be described as ZrO2/TiO+TiO2+Cu2Ti4O+Ni2Ti4O/α-Ti+(Ti,Zr)2(Cu,Ni) eutectic/acicular Widmanst¨aten structure/Ti-6Al-4V alloy. With the increase in the brazing temperature, the thickness of the TiO+TiO2+Cu2Ti4O+Ni2Ti4O layer reduced, the content of the α-Ti+(Ti,Zr)2(Cu,Ni) eutectic phase decreased, while that of the coarse α-Ti phase gradually increased. The shear strength of the joints did not show a close relationship with the thickness of the TiO+TiO2+Cu2Ti4O+Ni2Ti4O layer. However, when the coarse (Ti,Zr)2(Cu,Ni) phase was non-uniformly distributed in the α-Ti phase, or when α-Ti solely situated at the center of the joint, forming a coarse block or even connecting into a continuous strip, the shear strength greatly decreased.     

激光化学气相反应生长Ti（C,N）薄膜的成分及微观结构

运用ＸＲＤ，ＥＰＭＡ，ＴＥＭ等手段分析在Ｔｉ－６Ａｌ－４Ｖ基材上用激光化学气相色反应生长的Ｔｉ（Ｃ，Ｎ）薄膜的成分，结构，显微结构，可在基材表面的形成大面积均匀的Ｔｉ（Ｃ，Ｎ）膜层，为无明显择优取向的等轴纳米晶，其中有少量的Ｔｉ２Ｎ相，且Ａｌ，Ｖ含量低于基材。     

Improving fatigue performance of Ti-6Al-4V alloy via ultrasonic surface rolling process

The effect of a gradient nanostructured (GNS) surface layer obtained by ultrasonic surface rolling process (USRP) on the fatigue behavior of Ti-6Al-4 V alloy has been studied in this paper. Microstructure, surface topography, surface roughness and residual stress measurements were performed to characterize the surface under different conditions. Rotating bending fatigue tests were carried out to evaluate the fatigue behavior of different treatments. The results present a remarkable fatigue performance enhancement for the Ti-6Al-4 V alloy with a GNS surface layer obtained by application of USRP with respect to the untreated condition, notwithstanding its considerable surface roughness due to severe ultrasonic impacts and extrusions. Mechanical surface polishing treatment further enhances the beneficial effects of USRP on the fatigue performance. The significantly improved fatigue performance can mainly be ascribed to the compressive residual stress. Simultaneously, the GNS surface layer and surface work hardening have a synergistic effect that accompanies the effect of compressive residual stress.     

Pr激光表面合金化提高Ti－6Al－4V抗氧化性

采用激光Ｐｒ合金化表面处理，研究了Ｔｉ合金的高温氧比行为，结果表明，加入Ｐｒ改变了氧化膜结构，抑制了氧的短路扩散，并改善膜的附着性和塑性，氧化速度显著下降．