TiC-TiB2陶瓷与Ti6Al4V熔化连接及层状复合材料制备

通过引入Ti-6Al-4V合金板,采用超重力场燃烧合成技术,在制备细晶TiC-TiB2凝固陶瓷的同时,实现了陶瓷-钛合金的熔化扩散焊,进而制备出具有成分梯度特征的陶瓷-钛合金层状复合材料.陶瓷-钛合金层间接头组织表明,正是因超重力场燃烧合成的爆燃特性及超重力场对燃烧产物形成的高温真空环境,使得钛合金表面发生熔化,进而发生液态陶瓷-钛合金液相层间的原子互扩散现象,故在陶瓷-钛合金连接区形成钛合金与富钛碳化物呈相间分布且细小TiB2片晶镶嵌其上的凝固组织,并使陶瓷-钛合金接头呈现成分梯度特征,进而使得陶瓷-钛合金的连接抗剪强度达到450 MPa±35 MPa,层状复合材料硬度从陶瓷至钛合金一侧则呈线性逐渐减小.     

SiO2玻璃陶瓷与TC4钛合金的活性钎焊

分别采用活性钎料AgCuTi和TiZrNiCu对SiO2陶瓷和TC4钛合金进行了钎焊连接,使用扫描电镜和X射线衍射等手段对接头的界面组织和力学性能进行了研究.结果表明,采用两种钎料均能够实现对SiO2陶瓷和TC4钛合金的连接;SiO2/TiZrNiCu/TC4接头的典型界面为SiO2/Ti2O+Zr3Si2+Ti5Si3/(Ti,Zr)+Ti2O+TiZrNiCu/Ti基固溶体/TiZr-NiCu+Ti基固溶体+Ti2(Cu,Ni)/TC4;SiO2,AgCuTi/TC4接头的典型界面为SiO2/TiSi2+Ti4O7/TiCu+Cu2Ti4 O/Ag基固溶体+Cu基固溶体/TiCu/Ti2Cu/Ti+Ti2 Cu/TC4.当钎焊温度为880℃和保温时间为5 min时,SiO2/TiZrNiCu/TC4接头的最高抗剪强度为23 MPa;当钎焊温度为900℃和保温时间为5 min时,SiO2/AgCuTi/TC4接头的最高抗剪强度为27MPa.     

Cu + TiB2 composite filler for brazing Al2O3 and Ti-6Al-4V alloy

Al₂O₃ and Ti-6Al-4V alloy were brazed using Cu + TiB₂ composite filler, which manufactured by mechanical milling of Cu and TiB₂ powders. Typical interface microstructure of joint was Al₂O₃/Ti₄(Cu,Al)₂O/Ti₂Cu + Ti₃Al + Ti₂(Cu,Al)/Ti₂(Cu,Al) + AlCu₂Ti/Ti₂Cu + AlCu₂Ti + Ti₃Al + Ti₂(Cu,Al) + TiB/Ti(s.s) + Ti₂Cu/Ti-6Al-4V alloy. Based on temperature- and time-dependent compositional change, the formation of intermetallics in joint was basically divided into four stages: formation of interfacial Ti₄(Cu,Al)₂O in Al₂O₃ side, formation of Ti₂Cu, Ti₃Al, TiB, Ti₂Cu, and AlCu₂Ti in layers II and IV, formation of Ti₂(Cu,Al) and AlCu₂Ti in layer III, formation of Ti + Ti₂Cu hypereutectoid organization adjacent to Ti-6Al-4V alloy. TiB in situ synthesized in joint not only acted as low thermal expansion coefficient reinforcement to improve the mechanical properties at room temperature, but also as skeleton ceramic of joint to increase high temperature mechanical properties of Al₂O₃/Ti-6Al-4V alloy joint increasing. When the joint containing 30 vol.% TiB brazed at 930 °C and 10 min of holding time, the maximum room temperature shear strength of joint was 96.76 MPa, and the high temperature shear strength of joint was 115.16 MPa at 800 °C.     

Study of diffusion bonding of Ti-6Al-4V and ZQSn10-10 with metal interlayer

The diffusion bonding was carried out to join Ti alloy (Ti-6Al-4V) and tin-bronze (ZQSn10-10) with Ni and Ni Cu interlayer. The microstructures of the diffusion bonded joints were analyzed by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The results show that when the interlayer is Ni or Ni Cu transition metals both could effectively prevent the diffusion between Ti and Cu and avoid the formation of the Cu-Ti intermetallic compounds (Cu3Ti, CuTi etc.). But the Ni-Ti intermetallic compounds (NiTi, Ni3Ti) are formed on the Ti-6Al-4V/Ni interface. When the interlayer is Ni, the optimum bonding parameters are 830℃/10 MPa/30min. And when the interlayer is Ni Cu, the optimum bonding parameters are 850℃/10MPa/20min. With the optimum bonding parameters, the tensile strength of the joints with Ni and Ni Cu interlayer both are 155.8MPa, which is 65 percent of the strength of ZQSn10-10 base metal.     

HIP diffusion bonding of P/M titanium alloy Ti-6Al-4V and stainless steel 1Cr18Ni9Ti

The HIP diffusion bonding of P/M titanium alloy Ti-6A1-4V and stainless steel 1Cr18Ni9Ti using pure Ni as intermediate layer was studied. Bonding joint with complex bonding interface was obtained by HIPing pre-alloyed Ti-6Al-4V powders and stainless steel 1Crl 8Ni9Ti in a vacuum canning. The joint strengths were examined and the characteristics of bonding joint were observed. The result shows that the maximized strength of HIP diffusion bonding between P/M titanium alloy Ti-6Al-4V and stainless steel 1Cr18Ni9Ti can be up to 388 MPa and the microstructure of bonding joint is acceptable.     

Diffusion bonding/superplastic forming of Ti-6Al-6V-2Sn/SUS 304 stainless steel/Ti-6Al-6V-2Sn

The superplasticity of the Ti- 6Al- 6V- 2Sn alloy for different temperatures was evaluated by single-sheet free blowing. The optimal superplastic temperature for the Ti- 6Al- 6V- 2Sn alloy was found to be 850 °C. Diffusion bonding of Ti- 6Al- 6V- 2Sn and 304 stainless steel was carried out in a vacuum. The interface of both bonded alloys was examined by EPMA. The concentration profile of Ni exhibited a peak at the interlayer and a valley adjacent it, whereas that of Cr exhibited a peak where Ni showed the valley. X- ray diffraction (XRD) analyses showed that the Fe ₂ Ti, NiTi, and CrMn Intermetallic compounds and the Cr element formed at the interface. The thickness profiles of the blown specimens were measured and compared with theoretical calculations.     

Effect of parameters on interface of the brazed ZrO2 ceramic and Ti-6Al-4V joint using Ti-based amorphous filler

A commercially available Ti47 Zr28 Cu14 Ni11 (at. pct) amorphous filler foil was used to join ZrO2 ceramic and Ti-6Al-4V alloy. According to experimental observations, the interface microstructure accounts for the mechanical properties of the joints. The effects of brazing conditions and parameters on the joint properties were investigated. The joint shear strength showed the highest value of about 108 MPa and did not monotonously increase with the brazing time increasing. It was shown that decreasing of brazing cooling rate and appropriate filler foil thickness gave higher joint strength.     

Transient liquid phase (TLP) brazing of Mg–AZ31 and Ti–6Al–4V using Ni and Cu sandwich foils

Transient liquid phase (TLP) brazing of Mg–AZ31 alloy and Ti–6Al–4V alloy was performed using double Ni and Cu sandwich foils. Two configurations were tested; first, Mg–AZ31/Cu–Ni/Ti–6Al–4V and second, Mg–AZ31/Ni–Cu/Ti–6Al–4V. The effect of set-up configuration of the foils on microstructural developments, mechanical properties and mechanism of joint formation was examined. The results showed that different reaction layers formed inside the joint region depending on the configuration chosen. The formation of ? phase (Mg), ρ (CuMg₂), δ (Mg₂Ni) and Mg₃AlNi₂ was observed in both configurations. Maximum shear strength obtained was 57 MPa for Mg–AZ31/Ni–Cu/Ti–6Al–4V configuration and in both configurations, the increase in bonding time resulted in a decrease in joint strength to 13 MPa. The mechanism of joint formation includes three stages; solid state diffusion, dissolution and widening of the joint, and isothermal solidification.     

Improvement of joint strength in dissimilar friction welding of Ti-6Al-4V alloy to type-718 nickel-based alloy using the Au–Ni interlayer

ABSTRACT

An Au–Ni interlayer was used to improve the joint strength between the Ti-6Al-4V alloy friction welded to the 718 Ni-based alloy. The interlayer was melted and ejected at the interface of the joint during friction welding, showing that frictional heat played a role in brazing of the interlayer. The melted interlayer suppressed the formation of intermetallic compounds between titanium and nickel at the interface. The tensile strength of the joint significantly increased from 460?MPa for direct friction-welded joints, to 698?MPa when the interlayer was added. The mechanism underlying the strength improvement of the friction-welded joint was the unique phenomenon of a combination of brazing of the interlayer and diffusion of solutes in the base metal to the interlayer.     

中间钛片对TiB2基陶瓷/钛合金梯度复合材料组织性能的影响

在钛合金与陶瓷粉末之间引入厚度从0.5mm到1.5mm的中间钛片,采用自蔓延离心熔铸工艺快速制备出了TiB₂基陶瓷/钛合金梯度复合材料,经过XRD, FESEM 和 EDS分析表明,添加钛片对陶瓷相没有明显的影响,但随着中间钛片厚度的增加,不仅细化陶瓷基体并改善其组织均匀性,而且增加了梯度界面厚度,减小甚至消除了钛合金基底热影响区。同时,热真空条件下液态陶瓷与钛合金之间发生熔化连接和原子互扩散,进而在凝固后期诱发TiB₂与Ti液的包晶反应 ,TiB自Ti液中的析晶反应和TiB与Ti液的共晶反应,实现了TiB₂的消减及TiB的生长,不仅改善了界面的残余应力,而且获得了陶瓷/钛合金多尺度多层次复合。界面组织结构的梯度演化与陶瓷/钛合金的热匹配不仅使梯度材料的硬度呈连续变化,而且使界面剪切强度达到了316±25 MPa。     

Effects of Fabrication Parameters on Interface of Zirconia and Ti-6Al-4V Joints Using Zr55Cu30Al10Ni5 Amorphous Filler

ZrO₂ was brazed to Ti-6Al-4V using a Zr₅₅Cu₃₀Al₁₀Ni₅ (at.%) amorphous filler in a high vacuum at 1173-1273 K. The influences of brazing temperature, holding time, and cooling rate on the microstructure and shear strength of the joints were investigated. The interfacial microstructures can be characterized as ZrO₂/ZrO_2?x  + TiO/(Zr,Ti)₂(Cu,Ni)/(Zr,Ti)₂(Cu,Ni,Al)/acicular Widmanstäten structure/Ti-6Al-4V. With the increase in the brazing temperature, both the thickness of the ZrO_2?x  + TiO layer and the content of the (Zr,Ti)₂(Cu,Ni) phase decreased. However, the acicular Widmanstäten structure gradually increased. With the increase in the holding time, the (Zr,Ti)₂(Cu,Ni) phase decreased, and the thickness of the (Zr,Ti)₂(Cu,Ni) + (Zr,Ti)₂(Cu,Ni,Al) layer decreased. In addition, cracks formed adjacent to the ZrO₂ side under rapid cooling. The microstructures produced under various fabrication parameters directly influence the shear strength of the joints. When ZrO₂ and Ti-6Al-4V couples were brazed at 1173 K for 10 min and then cooled at a rate of 5 K/min, the maximum shear strength of 95 MPa was obtained.     

Brazing of 6061 aluminum alloy/Ti-6Al-4V using Al-Si-Cu-Ge filler metals

Al-8.4Si-20Cu-10Ge and mixed rare-earth elements (Re) containing Al-8.4Si-20Cu-10Ge-0.1Re filler metals were used for brazing of 6061 aluminum alloy/Ti-6Al-4V. The addition of 20 wt.% copper and 10 wt.% germanium into the Al-12Si filler metal lowered the solidus temperature from 586 °C to 489 °C and the liquidus temperature from 592 °C to 513 °C. The addition of 0.1 wt.% rare-earth elements into Al-8.4Si-20Cu-10Ge alloy caused remarkable Al-rich phase refinement and transformed the needle-like Al₂Cu intermetallic compounds into block-like shapes. Shear strengths of the 6061 aluminum alloy/Ti-6Al-4V joints with the two brazing filler metals, Al-8.4Si-20Cu-10Ge and Al-8.4Si-20Cu-10Ge-0.1Re, varied insignificantly with brazing periods of 10-60 min. The average shear strength of the 6061 aluminum alloy/Ti-6Al-4V joints brazed with Al-8.4Si-20Cu-10Ge at 530 °C was about 20 MPa. Rare-earth elements appeared to improve the reaction of the Al-8.4Si-20Cu-10Ge filler metal with Ti-6Al-4V. The joint shear strength of the 6061 aluminum alloy/Ti-6Al-4V with Al-8.4Si-20Cu-10Ge-0.1Re reached about 51 MPa.     

Effect of Zr addition on microstructures and mechanical properties of Ni-46Ti-4Al alloy

The microstructures and mechanical properties of Ni-(46-x)Ti-4Al-xZr (x = 0-8, at.%) alloys have been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and mechanical tests. The results show that the Ni-Ti-Al-Zr alloys are composed of TiNi and (Ti, Al) 2 Ni with Zr as a solid solution element in both phases, and the third phase, (Zr, Ti, Al) 2 Ni, appears in Ni-40Ti-4Al-6Zr and Ni-38Ti-4Al-8Zr alloys. The compressive yield strength at room temperature increases with the increase of Zr content due to the solid-solution strengthening of Zr and precipitation strengthening of (Ti, Al, Zr) 2 Ni phase. However, the Ni-42Ti-4Al-4Zr alloy exhibits the maximum compressive yield strength at 873 and 973 K because of the softening of (Zr, Ti, Al) 2 Ni phase in the alloys with more Zr addition. The tensile stress-strain tests and the SEM fracture surface observations show that the brittle to ductile transition temperature of Ni-42Ti-4Al-4Zr alloy is between 873 and 923 K.     

The in situ synthesis and wear performance of a metal matrix composite coating reinforced with TiC-TiB2 particulates, formed on Ti-6Al-4V alloy by a low oxygen partial pressure fusing technique

A metal matrix composite coating reinforced with TiC-TiB₂ particulates has been successfully fabricated utilizing the in situ reaction of Al, Ti and B₄C by the low oxygen partial pressure fusing technique to improve the wear resistance of Ti-6Al-4V alloy. The results show that increasing the B₄C content is adverse to forming the coating for the formation of interfacial stress; however, the addition of TiC powder as a diluent can favor the formation of this coating and the addition of small amounts of Y₂O₃ can greatly improve the adhesion of the coating. After a pin-on-disc wear test, the wear mass loss of the coating is only about 1/12 that of the Ti-6Al-4V alloy and the wear mechanism of coating is a mixed type of slight peeling-off, adhesion and abrasion.     

Low-melting-point titanium-base brazing alloys—part 1: Characteristics of two-, three-, and four-component filler metals

The melting point, microstructure, phase, and electrochemical behavior of Ti-21Ni-15Cu alloy, together with two-, three-, and four-component low-melting-point titanium-base brazing alloys, are presented in this paper. Five filler metals were selected for the study, in which melting points were measured by differential thermal analysis, phases identified by x-ray diffractometry, and corrosion behaviors tested by potentiodynamic polarization. The experimental results show that the three-component Ti-15Cu-15Ni and the newly developed Ti-21Ni-14Cu alloys exhibit the combination of lower melting point and superior corrosion resistance compared to the two-and four-component titanium alloys, 316L stainless steel, and a Co-Cr-Mo alloy in Hank’s solution at 37 °C. On a short time basis, the presence of Ti₂Ni and Ti₂Cu intermetallics in the Ti-15Cu-15Ni and Ti-21Ni-14Cu alloys should not be preferentially dissolved in galvanic corrosion with respect to the dissimilar Ti-6Al-4V alloy.     

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.     

Ti811和TC4合金的热盐应力腐蚀行为研究

研究了Ti811(Ti-8Al-1Mo-1V)和TC4(Ti-6Al-4V)两种钛合金对热盐应力腐蚀(HSSC)的敏感性.结果表明:Ti811合金对HSSC非常敏感,在相同条件下其热盐应力腐蚀临界应力(σHSSC)明显低于TC4合金,且低于同温度的蠕变强度,而TC4合金的σHSSC高于同温度的蠕变强度;两种合金在HSSC暴露过程中,明显遭受到盐腐蚀,腐蚀产生的氢扩散到基体中,致使合金发生脆化,从而降低合金的室温塑性.     

A comparative study on titania layers formed on Ti, Ti-6Al-4V and NiTi shape memory alloy through a low temperature oxidation process

For improving the bioactivity and biocompatibility of metals for medical applications, anatase titania layers were synthesized on Ti, Ti-6Al-4V and NiTi shape memory alloy (SMA) using the H₂O₂-oxidation and hot water aging treatment method at 80 °C. The thickness of the titania layers on Ti, Ti-6Al-4V and NiTi SMA was 7.43 ± 0.93 μm, 3.14 ± 0.38 μm and 4.04 ± 0.25 μm, respectively. X-ray diffraction (XRD) and transmission electron microscopic (TEM) analysis indicated that the titania layers formed were poorly crystalline anatase. Fourier transform infrared spectroscopy (FTIR) suggested that abundant Ti-OH functional groups were produced on titania, which could improve bioactivity of the metals. In addition, the titania layer formed on Ti substrate was shown to contain more molecularly chemisorbed water and Ti-OH functional groups than those on Ti-6Al-4V and NiTi SMA. Atomic force microscopic (AFM) results showed that the surface roughness values of metal samples depended on the scanning size and that surface roughness of samples significantly increased after the H₂O₂-oxidation and hot water aging treatment for all three metals. Compared to Ti-6Al-4V and NiTi SMA, the H₂O₂-treated and aged Ti samples exhibited the roughest surface. The wettability of samples was evaluated through water contact angle measurements. After the H₂O₂-oxidation treatment, the three metals exhibited high hydrophilicity. The bonding strength of titania layers on Ti, Ti-6Al-4V and NiTi was also investigated. Potentiodynamic polarization tests indicated that the corrosion resistance of H₂O₂-treated and aged Ti, Ti-6Al-4V and NiTi SMA was significantly improved due to the titania layer formation.     

Ti_2AlNb相合金Ti-22Al-25Nb的TLP扩散连接

以Ti-15Cu-15Ni合金薄带作中间层,用Gleeble 1500D热-力学模拟试验机对Ti2AlNb相合金Ti-22Al-25Nb进行TLP扩散连接。研究了连接参数对接头组织演变、元素分布、接头强度及其断裂特征的影响。结果表明,接头形成过程由5个阶段组成,Nb是接头成分均匀化的扩散主控元素。适当延长保温时间和适当提高连接温度有利于获得组织与成分均匀的高强接头。保温结束后接头快速冷却时,其连接区室温组织为B2相;而采用慢冷工艺有利于促进高温β相的相变从而改善连接区组织,室温组织为B2相基体和少量α2、O相。连接温度和保温时间分别为990℃和90min且采用慢冷工艺时,接头的室温和650℃抗拉伸强度分别为1041MPa和659MPa,分别达到原始母材强度的95％和81％,明显高于采用快冷工艺的接头强度。     

High-strength Ti-Al-V-Zr cast alloys designed using α and β cluster formulas

Ti-Al-V-Zr quaternary titanium alloys were designed following α-{[Al-Ti₁₂](AlTi₂)}_17−n+β-{[Al-Ti₁₂Zr₂](V₃)}_n, where n=1–7 (the number of β units), on the basis of the dual-cluster formula of popular Ti-6Al-4V alloy. Such an alloying strategy aims at strengthening the alloy via Zr and V co-alloying in the β-Ti unit, based on the original β formula [Al-Ti₁₄](V₂Ti) of Ti-6Al-4V alloy. The microstructures of the as-cast alloys by copper-mold suction-casting change from pure α (n=1) to α+α′ martensite (n=7). When n is 6, Ti-5.6Al-6.8V-8.1Zr alloy reaches the highest ultimate tensile strength of 1,293 MPa and yield strength of 1,097 MPa, at the expense of a low elongation of 2%, mainly due to the presence of a large amount of acicular α′ martensite. Its specific strength far exceeds that of Ti-6Al-4V alloy by 35%.