铁中间层钛-钢扩散复合界面组织与性能

利用真空扩散焊方法制备了铁中间层钛-钢扩散焊接头,并采用OM、SEM、EDS、XRD、显微硬度和拉伸试验方法,研究了铁中间层钛-钢扩散复合界面组织和性能。结果表明,在900～1050℃、30 min扩散条件下,Fe、Ti原子在界面处发生了互扩散;钛侧形成βTi+α-βTi+αTi组织,钢侧发生脱碳,铁中间层形成柱状晶组织;拉伸强度随扩散温度升高呈现先增加后减小的趋势,900℃、30 min扩散试样拉伸强度最高,达到260 MPa;拉伸断口具有粗糙断裂区、脆性断裂区及二次断裂区特征,并在断口上检测出TiC、FeTi和Fe2Ti相。     

钛-钢扩散复合界面组织与结合强度

将钛管、钢管利用冷拔-内压扩散法制备了内包覆钛-钢复管.用扫描电镜、能谱分析、X-光衍射和拉剪试验等方法,研究了扩散退火温度与时间对钛-钢扩散复合界面附近组织、成分和界面剪切强度的影响.结果表明,该制备方法可使钛-钢实现冶金结合;界面剪切强度随扩散温度升高先增加后减小;750-800℃×0.5h扩散退火界面剪切强度最高,可达210MPa左右;扩散退火中Fe、Ti原子发生了互扩散;界面上有TiC形成;750℃×0.5 h扩散退火试样断口未检测到TiFe、TiFe2相;900-950℃×0.5h扩散退火钢侧出现柱状晶区,钛侧出现无晶界晶区与针状马氏体晶区.     

钛/铜中间层/钢扩散焊复合管界面组织与性能

以铜箔为中间层,采用拉拔—内压扩散法制备钛/钢复合管.利用光学显微镜、扫描电子显微镜、X-光衍射仪和能谱仪对界面组织、断口形貌和成分进行分析,通过剪切试验测定界面的结合强度.结果表明,以铜箔作中间层,拉拔—内压扩散法实现了钛/钢的冶金结合;在钛/铜界面处发生了明显的原子扩散,并形成不同的扩散层;随着扩散温度和时间的增加扩散层的厚度逐渐增加;中间层的加入阻止了固相扩散中钛铁、钛碳脆性化合物生成;钛/钢界面的抗剪强度随着扩散温度的升高先增加后降低,铜层的加入使抗剪强度明显提高,最高可达310 MPa.     

钒中间层钛/钢复合板结合界面结构与力学性能

利用真空热轧复合方法制备了钒中间层钛/钢复合板,采用SEM、EDS和XRD等分析结合界面形貌、元素扩散行为和界面相组成。结果表明:钒中间层钛/钢复合板界面实现了良好的冶金结合。与拉剪强度测试相结合,研究了钒中间层钛/钢复合板结合界面结构与力学性能。结果表明:钒中间层钛/钢复合板剪切强度均优于国家标准(140 MPa)。950℃轧制的复合板界面扩散层厚度大于900℃轧制的复合板扩散层厚度。钒中间层与Ti、Fe元素形成固溶体,有效阻止了金属间化合物TiFe和TiFe_2的产生。900℃轧制的钛钢复合板剪切强度为223 MPa,大于950℃轧制的复合板剪切强度。对剪切断口的分析表明裂纹多沿钒铁固溶体产生并扩展。     

钛-钢扩散复合界面组织与结合强度

将钛管、钢管利用冷拔-内压扩散法制备了内包覆钛-钢复管。用扫描电镜、能谱分析、X-光衍射和拉剪试验等方法，研究了扩散退火温度与时间对钛-钢扩散复合界面附近组织、成分和界面剪切强度的影响。结果表明，该制备方法可使钛～钢实现冶金结合；界面剪切强度随扩散温度升高先增加后减小；750—800℃×0．5h扩散退火界面剪切强度最高，可达210MPa左右；扩散退火中Fe、Ti原子发生了互扩散；界面上有TiC形成；750℃×0．5h扩散退火试样断VI未检测到TiFe、TiFe2相；900—950℃×0．5h扩散退火钢侧出现柱状晶区，钛侧出现无晶界晶区与针状马氏体晶区。     

钛/铜/不锈钢脉冲加压扩散连接接头组织及力学性能研究

为了提高钛/不锈钢扩散连接接头性能,缩短连接时间,抑制界面反应产物的过度生长,本文采用50μm纯铜箔做中间层,进行脉冲加压扩散连接。通过扫描电镜观察、万能拉伸试验和XRD分析对钛/铜/不锈钢接头界面组织和力学性能进行了分析。结果表明,当连接时间为120 s时即可得到可靠的接头。在钛/铜界面生成了Ti2Cu、Ti Cu、Ti3Cu4和Ti Cu4等金属间化合物层,而在铜/不锈钢界面生成了Fe-Cu固溶体。在拉伸载荷下,试样沿钛/铜界面反应产物发生脆性断裂,接头强度达到了340 MPa。     

金属的焊接性

TC4／Cu／ZQSn10-2—3扩散连接接头微观分析 TC4／ZQSn10-2—3直接扩散连接时,结合区由于生成CuSn3Ti5,Cu3Ti等金属间化合物及集聚的Pb质点,接头强度不高（tmax=102MPa）,断口为脆性断口,并发生在靠近ZQSn10-2-3侧;填加金属中间层铜时,T以／Cu／ZQSn10-2—3扩散连接接头强度获得显著提高（tmax=196MPa）,这主要是铜中间层有效地抑制了Sn,Pb等元素向TC4侧的扩散,减少CuSn3Ti5,     

金属的焊接性

TC4／Cu／ZQSn10-2—3扩散连接接头微观分析 TC4／ZQSn10-2—3直接扩散连接时,结合区由于生成CuSn3Ti5,Cu3Ti等金属间化合物及集聚的Pb质点,接头强度不高（tmax=102MPa）,断口为脆性断口,并发生在靠近ZQSn10-2-3侧;填加金属中间层铜时,T以／Cu／ZQSn10-2—3扩散连接接头强度获得显著提高（tmax=196MPa）,这主要是铜中间层有效地抑制了Sn,Pb等元素向TC4侧的扩散,减少CuSn3Ti5,     

轧制加热温度对钛/钢复合板组织与性能的影响

采用钢/钛/隔离剂/钛/钢对称结构复合板坯,研究了轧制加热温度(850-1000℃)对钛/钢复合板显微组织、基材强韧性和界面结合性能的影响。结果表明,随着轧制加热温度的升高,界面剪切性能逐步下降。加热温度影响着界面反应相的种类和厚度。在850,875,900℃条件下,轧后冷却扩散过程中,C极容易在钛/钢界面形成TiC层,阻碍了Fe向Ti中扩散,因而界面形成TiC和β-Ti反应层;在950℃和1000℃条件下,由于C在β-Ti中的扩散系数为C在γ-Fe扩散系数的10倍以上,C不能在结合界面富集形成有效的TiC屏障,此时Fe能够在Ti中充分扩散,从而形成了Fe-Ti金属间化物层、TiC层、β-Ti层和α-β Ti层。脆性反应相的厚度与加热温度呈正相关关系。脆性相种类和厚度增加使得钛/钢复合板界面剪切强度出现下降。     

碳化硅复合材料与碳钢钎焊接头的抗剪强度及微观结构

采用磁控溅射镀膜技术对碳/碳化硅复合材料(C/SiC)表面进行镀Ti金属化,以AgCu₂₈为钎料,无氧铜为中间层与碳钢进行钎焊连接. 研究无氧铜中间层、Ti膜厚度和钎焊温度对接头组织形貌和力学性能的影响. 结果表明,采用无氧铜中间层可有效降低接头的残余应力,提高接头强度,并阻挡C/SiC复合材料中的Si元素在钎焊过程中扩散至碳钢侧,防止了碳钢界面FeSi_x恶性反应层的形成. 在试验范围内,钛膜厚度和钎焊温度与接头抗剪强度之间均存在峰值关系. 860 ℃,3 μm Ti膜接头平均抗剪强度最高,达到25.5 MPa. 由剪切试样碳钢侧断口,可观察到大量平行断口方向的碳纤维和碳纤维脱粘坑. 断裂发生在C/SiC复合材料内部距界面约300 μm处. C/SiC界面反应产物以Ti₅Si₃为主,含少量TiC. 钎缝中有TiCuSi相生成.     

Microstructure and mechanical properties of diffusion bonded titanium/304 stainless steel joint with pure Ag interlayer

Abstract

In the present study, diffusion bonding of commercially pure titanium to 304 stainless steel (SS) using a pure Ag interlayer was carried out. It is found that the pure Ag interlayer can effectively block the interdiffusion and interaction between Ti and SS. The resultant joints were composed of Ti substrate, Ti–Ag solid solution, TiAg intermetallic phase, the remnant Ag interlayer and SS. Upon tensile loading, fracture took place through the remnant Ag interlayer, indicating that the TiAg intermetallic phase exhibits no detrimental effect on the strength of the joints. A maximum tensile strength of 421 MPa was achieved, which is notably improved compared with previous results. Furthermore, extensive dimples were observed on the fracture surfaces, clearly indicating that the joints were ductile in nature.     

采用铌中间层的钛合金与不锈钢的真空热轧连接界面的显微组织及性能

进行了钛合金与不锈钢采用铌中间层的真空热轧连接实验,分析了连接界面的显微组织及性能。结果表明,采用铌中间层能够明显提高接头的塑性。当压缩率为25%,轧制速度为38 mm/s,热轧温度为800°C和900°C时,不锈钢与铌的连接界面没有明显的金属间化合物层;当热轧温度为1000°C和1050°C时,不锈钢与铌连接界面形成Fe-Nb金属间化合物层,并且当热轧温度为1050°C时在金属间化合物层与不锈钢之间出现开裂。铌与钛合金连接界面的扩散层厚度随着热轧温度的升高而增大。热轧温度为900°C的连接接头的拉伸强度可达-417.5MPa,拉伸试样断裂于铌中间层,断口呈塑性断裂特征。热轧温度为800°C的热轧过度接头分别与钛合金和不锈钢进行TIG焊接,TIG焊后热轧过度接头的拉伸强度可达-410.3 MPa,拉伸试样断裂于铌中间层,断口呈塑性断裂特征。     

Impulse pressuring diffusion bonding of titanium to 304 stainless steel using pure Ni interlayer

In the present study,impulse pressuring diffusion bonding technology(IPDB)was utilized between commercially pure titanium and 304 stainless steel(SS)using pure nickel(Ni)as interlayer metal.The interfacial microstructures of the bonded joints were investigated by scanning electron microscopy(SEM)and energy dispersive spectroscope(EDS)analyses.It is found that with the aid of the Ni interlayer,the interdiffusion and reaction between Ti and SS can be effectively restricted and robust joints can be obtained.Intermetallic compounds(IMCs)including Ti_2Ni,Ti Ni,and TiNi_3 are detected at the Ti/Ni interface;however,only Ni–Fe solid solution is found at the Ni/SS interface.The maximum tensile strength of 358 MPa is obtained by IPDB for 90 s and the fracture takes place along the Ti_2Ni and Ti Ni phase upon tensile loading.The existence of cleavage pattern on the fracture surface indicates the brittle nature of the joints.     

镍作中间层脉冲加压扩散连接钛合金与不锈钢

采用纳米Ni粉、纳米Ni镀层、Ni箔作中间过渡层,对TA17近。型钛合金与0Cr18Ni9Ti不锈钢进行了脉冲加压扩散连接,接头抗拉强度分别达到了175,212,334MPa。在金相显微镜下,对拉伸断口形貌进行了观察和分析;利用扫描电镜（SEM）、能谱仪（EDS）、X射线衍射分析（XRD）测定了连接接头各区域内的微区成分和物相。结果表明,纳米Ni粉致密度不够高,纳米Ni镀层质量不够高,在很大程度上限制了接头强度的提高;Ni箔中间层的存在成功地阻止了Fe与Ti之间的互扩散,避免了形成脆而硬的Fe—Ti系金属间化合物。     

Fracture behaviour of diffusion bonded titanium alloys with strength mismatch

Abstract

The present study considers the effect of strength mismatch on the fracture behaviour of diffusion bonded joints between commercially pure (CP) Ti and Ti-6Al-4V (Ti64), including dissimilar joints and sandwich structures with strength undermatching and overmatching. The aim of the investigation is to determine the influence of the interlayer thickness (for both higher and lower strength interlayers) and the bond quality on the deformation behaviour and fracture toughness of the joints. The influence of mechanical heterogeneity (strength mismatch) on the fracture behaviour of the interface in dissimilar joints was also investigated. Round bars of CP Ti and Ti64 having a diameter of 40 mm were diffusion bonded as dissimilar butt joints and sandwich structures containing lower strength (undermatching) and higher strength (overmatching) interlayers of different thicknesses. Round transverse tensile specimens and standard four point bend (single edge notch bend) specimens were extracted from the joints via spark erosion cutting. The four point bend specimens were fatigue precracked to introduce a sharp crack after introducing machine notches at the centre of the interlayers in the sandwich structures and at the interface in the dissimilar joints, and tested at room temperature. Some specimens were also prepared with the crack positioned away from the interface to determine the effect of notch position on fracture behaviour. The effect of strength mismatch on the crack tip opening displacement fracture toughness parameter of the joints has been evaluated. Crack initiation, crack growth, and crack deviation processes have been examined and fracture resistance curves (R curves) constructed for the joints. These results were used to explain the influence of mechanical heterogeneity of the joints and interlayer thickness on fracture behaviour.     

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.     

Interfacial structure and mechanical properties of hot roll bonded joints between titanium alloy and stainless steel using copper interlayer

Abstract

The hot roll bonding was carried out in vacuum condition between titanium alloy and stainless steel using copper interlayer. The stainless steel/Cu can not be bonded if the bonding temperature is lower than or equal to 730°C, and the Cu–Ti alloy can not be bonded if the bonding temperature is higher than or equal to 880°C. The testing results show that the total thickness of intermetallic layers at the interface between copper and titanium alloy increases with the bonding temperature, and the tensile strength of bonded joints decreases with increasing bonding temperature. The maximum strength of 343 MPa was obtained at the bonding temperature of 780°C, the reduction of 20% and the rolling speed of 38 mm s^–1.     

钛合金与不锈钢超塑性扩散连接工艺及机理研究

基于微细晶超塑性扩散连接方法,对TC4钛合金与1Cr18Ni9Ti不锈钢成功实现了直接扩散连接,系统分析了接头性能、界面微观结构及超塑性扩散连接机理。结果发现：TC4钛合金与1Cr18Ni9Ti奥氏体不锈钢直接超塑性扩散连接时,较佳连接工艺规范为：温度T=760~820 ℃,压力p=6~9 MPa,时间t=20~40 min;接头剪切强度τ＝125.3~148.7 MPa。与一般直接扩散连接相比,连接温度降低了约100 ℃,接头的剪切强度提高了1倍以上,且连接试样无明显变形。细化热处理TC4钛合金与1Cr18Ni9Ti不锈钢超塑性扩散连接时,其接头的形成过程大致可分为3个阶段：形成紧密接触阶段、接触表面激活阶段及靠近活化中心的界面冶金结合区形成阶段。     

TC4/Ti60合金钎焊接头界面组织及力学性能

采用TiZrNiCu非晶钎料实现了TC4和Ti60异种钛合金的真空钎焊连接,利用扫描电子显微镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)等分析手段研究了钎焊工艺参数对接头界面组织结构及力学性能的影响. 结果表明,TC4/TiZrNiCu/Ti60钎焊接头的典型界面结构为:TC4/α-Ti+β-Ti+(Ti,Zr)2(Ni,Cu)/Ti60. 随着钎焊温度升高或保温时间延长,片层状α+β相逐渐填充整条钎缝,(Ti,Zr)2(Ni,Cu)相含量减少且分布更加均匀. 接头室温抗拉强度随钎焊温度或保温时间的增加均先增大后减小,在990 ℃/10 min钎焊条件下所获接头抗拉强度达到最大为535.3 MPa. 断口分析结果表明,断裂位于钎缝中,断裂方式为脆性断裂.