铜/钛合金电子束焊接工艺优化

研究了QCr0.8/TC4电子束焊接工艺及接头组织,由于铜合金热导率高而熔化量较小,以及焊缝中生成大量脆性金属间化合物相,因此对中焊时接头强度较低.采用偏铜侧进行非对中电子束焊接,接头抗拉强度随偏束量的增大而增高,偏束量为0.8mm时接头最高抗拉强度为270.5MPa.断裂发生在TC4侧熔合线处,为脆性准解理断裂特征.偏铜焊时接头成形得到改善,焊缝包括熔合区及TC4侧反应层两部分.熔合区主要由铜基固溶体组成,硬度较TC4母材有所降低.反应层成分过渡较大,含有多种金属间化合物相.随着工艺参数的变化,反应层厚度也发生变化,从而对接头性能产生影响.     

QCr0.8/TC4薄板电子束焊接头组织及断裂路径

对QCr0.8/TC4异种材料薄板进行了电子束对接焊接试验.采用光学金相、扫描电镜、能谱分析及X射线衍射相分析等方法,对接头组织结构及相组成进行了分析.并对接头进行了性能测试及断口形貌观察,分析了断裂性质,探讨了断裂路径.结果表明,焊缝由大量的γ-CuTi相、金属间化合物CuTi2,CuTi3及少量的铜基固溶体组成,且靠近铜合金侧存在一层20 μm左右的反应层,推测其可能为Ti2Cu,CuTi,Cu4Ti3,Cu2Ti,Cu3Ti等多种金属间化合物混合层;QCr0.8/TC4的电子束对中焊接性较差,接头断裂发生在焊缝中心的粗晶区,呈明显的解理断裂特征,接头抗拉强度很低,仅为82.1 MPa.     

TC4/OFC真空扩散焊接研究

对钛合金（TC4）与无氧纯铜（OFC）异种金属在真空条件下进行直接扩散焊接,可形成良好的TC4/ OFC焊接接头。测量其焊接强度及进行微区分析的结果表明,随着温度升高,焊接接头的抗拉强度先升高后下降,最佳焊接工艺参数为：焊接温度800 ℃,保温时间30 min,焊接压力5 MPa。在TC4/ OFC焊接接头的界面上形成了元素成分逐渐变化的互扩散层。由元素分析和断口的XRD分析结果可以看出,界面处生成的物相有Cu3Ti2、Cu4Ti3、CuTi、Cu4Ti等金属间化合物,断口的形貌表明接头断裂主要发生在接头的金属间化合物弱结合处,结合处的孔洞与铜钛金属间化合物的种类、厚度决定了TC4/OFC直接扩散焊接接头的强度。     

Cu/Ti电子束叠加焊接对金属间化合物层的影响(英文)

对QCr0.8/TC4进行电子束焊接,研究焊缝中金属间化合物层(即IMC-layer)对接头力学性能的不利影响,提出利用电子束二次叠加焊接方式来改善接头性能的思路。结果表明,对中焊时在铜侧熔合线处形成的金属间化合物层,偏铜侧焊接时在钛侧熔合线处形成的金属间化合物层,是接头中的薄弱环节。利用电子束叠加焊接方式,须合理设计焊接顺序。先进行对中焊,再利用偏铜侧焊接,可将第一道焊缝形成的金属间化合物层破碎重熔,形成组织较好的化合物层,改善接头的力学性能。接头的抗拉强度为276.0MPa,达到了母材强度的76.7%。     

板厚对Ti60钛合金电子束焊接头显微组织及力学性能的影响

研究了不同厚度Ti60钛合金板材电子束焊接接头的显微组织与力学性能。研究结果表明,不同厚度Ti60合金板材的焊接接头均由熔合区、热影响区和母材区组成,熔合区由粗大的柱状晶组成。板材厚度对柱状晶内部显微组织影响很小,不同厚度的板材熔合区柱状晶内的显微组织相似,均由细小的片层α相和少量β相组成,不同厚度的板材电子束焊接接头熔合区均具有较高的硬度和强度。700℃焊后热处理会使熔合区α相的边界处析出大量的硅化物。     

石英纤维复合材料与因瓦合金的胶接辅助钎焊连接分析

通过表面涂覆活性胶改性的方法,实现了石英纤维复合材料与因瓦合金的胶接辅助钎焊连接.结果表明,含有钛的液态活性胶在焊接加热过程中与石英纤维复合材料表面纤维发生反应,并通过Ag-Cu共晶钎料层、铜中间层与因瓦合金获得致密连接,接头产生TiO,TiC,CuTi,Fe2Ti等化合物,其结构可表示为QFSC/TiO+Si+TiC+Cu(s,s)/CuTi+Cu(s,s)+Ag(s,s)/Cu(s,s)+Ag(s,s)+Fe2Ti/Invar.由不同钎焊温度接头的剪切性能对比试验得出,在850℃保温15min时的接头抗剪强度达到最大值44MPa.表面涂覆活性胶对钎料润湿的促进作用、活性金属元素Ti与复合材料纤维的化学反应及接头焊缝区产生的化合物生成相是影响连接性能的主要因素.     

Super-Ni叠层复合材料与钛合金过渡液相扩散焊界面组织特征

以铜箔为中间层,对Super-Ni叠层复合材料与Ti-6Al-4V钛合金进行过渡液相扩散焊.通过扫描电镜(SEM)、能谱分析(EDS)、显微硬度测试对接头的界面组织及性能进行分析.结果表明,铜箔中间层阻止了钛与镍的扩散接触,防止了Ti-Ni脆性金属间化合物的生成.扩散焊接头由Super-Ni侧扩散层、中间反应层、钛侧扩散层三个特征界面层组成.界面处Ni,Al原子扩散缓慢,Cu,Ti原子充分扩散反应,在中间反应层与钛侧扩散层之间形成由TiCu相组成的锯齿状界面,在钛侧扩散层生成细小的Ti_2Cu相,接头过渡区显微硬度最高达600 HV0.5.     

填充金属对钛合金与不锈钢电子束焊接的影响(英文)

采用Ni、V、Cu等填充材料进行钛合金与不锈钢的电子束焊接实验。采用光学显微镜、扫描电镜及X射线衍射对接头的微观组织进行分析。通过抗拉强度和显微硬度评价接头的力学性能,分析讨论填充材料对钛/钢电子束焊接接头微观组织和力学性能的影响。结果表明:填充材料有助于抑制Ti-Fe金属间化合物的产生。所有接头均由固溶体和界面化合物组成。对于不同的填充材料,固溶体和界面化合物种类取决于填充材料与母材之间的冶金反应。对于Ni、V及Cu填充材料,界面化合物分别为Fe2Ti+Ni3Ti+NiTi2,TiFe和Cu2Ti+CuTi+CuTi2。接头抗拉强度主要取决于金属间化合物的脆性。采用Cu填充金属的接头抗拉强度最高,约为234 MPa。     

Cu基材料作焊接过渡层TA1/Q345复合板接头的组织与性能

以Cu-Ag-Mo药芯焊丝为焊接中间层过渡材料,对TA1/Q345双金属层状复合板进行熔焊试验。利用SEM、EDS和XRD等分析方法对接头元素分布、相组成及组织构成进行了微观分析,并进行了焊缝区显微硬度测试。结果表明:钛焊缝中,微量的Fe向上扩散形成了少量的金属间化合物Ti Fe,在拉伸应力的作用下产生了裂纹,但在过渡层中的Ag元素具有很好的流动性,填补了裂纹,阻碍了裂纹的扩展;过渡层Mo元素与扩散Ti形成了连续固溶体,降低了过渡区中扩散Ti的含量,控制了Ti、Fe金属间化合物的生成;焊缝区的显微硬度值整体呈下降趋势,但其中钛焊缝与过渡层界面处的硬度值高达475 HV0.1,该区域的主要相为Ti Cu和Ti2Cu,降低了焊接接头塑韧性。     

异种高温钛合金电子束焊接接头组织与性能

采用真空电子束焊机对高温钛合金Ti60板材和Ti700sr铸件进行焊接,并对接头显微组织和力学性能进行了研究. 结果表明,高温钛合金Ti60板材和Ti700sr铸件电子束焊接性良好,可以获得优质的接头. 获得的接头中焊缝为细小针状马氏体组织,Ti700sr侧熔合区马氏体内部存在层错和孪晶. Ti700sr侧热影响区相比于母材网篮状的α相长大. Ti60侧熔合区和热影响区均发现富Nd稀土弥散相析出. 焊缝区显微硬度与Ti60和Ti700sr母材相当,基本在360 HV左右.硬度最高点出现在Ti60侧热影响区,硬度最大值达到418 HV.接头室温抗拉强度达到1 100 MPa以上,断裂于Ti60热影响区. 接头600 和650 ℃高温抗拉测试均失效断裂在Ti60母材. 其中接头600 ℃高温拉伸性能均值为695 MPa,650 ℃高温拉伸性能均值为587 MPa.     

Contact Reactive Joining of TA15 and 304 Stainless Steel Via a Copper Interlayer Heated by Electron Beam with a Beam Deflection

TA15 titanium alloy and 304 stainless steel were joined via a copper interlayer heated by electron beam with a beam deflection towards the stainless steel. Microstructures of the joints were analyzed by optical microscopy, scanning electron microscopy, and X-ray diffraction. The tensile strengths of the joints and the ultramicrohardness of the intermetallic compounds were also measured. The results showed that the joint was formed by three kinds of metallurgical processes. Copper interlayer and TA15 were joined by contact reaction with the reaction products of CuTi, Cu₄Ti₃, and Cu₂Ti. While copper interlayer and 304 stainless steel were joined by fusion and solid state diffusion process. Tensile strength of the joint can reach to 300?MPa, equivalent to 55% of that of 304 stainless steel. Furthermore, the tensile strength was mostly dependent on the volume of the unmelted copper sheet, although the intermetallics layer was the weakest location in the joint.     

AgCu钎料钎焊TC4钛合金与QCr0.8铬青铜接头界面结构及性能

采用AgCu28钎料实现了TC4钛合金与QCr0.8铬青铜的真空钎焊,利用SEM, EDS以及XRD等分析方法确定TC4/AgCu/QCr0.8接头的典型界面结构为TC4钛合金/CuTi +Cu3Ti2 +CuTi2/Ag(s,s) +Cu4Ti/Ag(s,s)+Cu(s,s)/QCr0.8铬青铜. 研究了工艺参数对接头组织和性能的影响. 结果表明,随着钎焊温度和保温时间的增加,钎缝中银铜共晶组织减少,钛铜化合物增多. 接头抗剪强度随钎焊温度的升高先增加后降低,在钎焊工艺参数为890 ℃/0 min时,获得最大抗剪强度449 MPa.保温时间的延长使得接头脆性钛铜化合物增多,接头性能下降,因此随保温时间延长接头抗剪强度显著降低.     

热循环对Sn58Bi(纳米Ti)/Cu焊点界面与性能影响

为了改善Sn-58Bi低温钎料的性能,通过在Sn-58Bi低温钎料中添加质量分数为0.1%的纳米Ti颗粒制备了Sn-58Bi-0.1Ti纳米增强复合钎料。在本文中,研究了纳米Ti颗粒的添加对-55～125 _^oC热循环过程中Sn-58Bi/Cu焊点的界面金属间化合物(IMC)生长行为的影响。研究结果表明：回流焊后,在Sn-58Bi/Cu焊点和Sn-58Bi-0.1Ti/Cu焊点的界面处都形成一层扇贝状的Cu₆Sn₅ IMC层。在热循环300次后,在Cu₆Sn₅/Cu界面处形成了一层Cu₃Sn IMC。Sn-58Bi/Cu焊点和Sn-58Bi-0.1Ti/Cu焊点的IMC层厚度均和热循环时间的平方根呈线性关系。但是,Sn-58Bi-0.1Ti/Cu焊点的IMC层厚度明显低于Sn-58B/Cu焊点,这表明纳米Ti颗粒的添加能有效抑制热循环过程中界面IMC的过度生长。另外计算了这两种焊点的IMC层扩散系数,结果发现Sn-58Bi-0.1Ti/Cu焊点的IMC层扩散系数(整体IMC、Cu₆Sn₅和Cu₃Sn IMC)明显比Sn-58Bi/Cu焊点小,这在一定程度上解释了Ti纳米颗粒对界面IMC层的抑制作用。     

Vacuum diffusion bonding of Ti2AlNb alloy and TC4 alloy

The Ti₂AlNb alloy was joined with TC4 alloy by vacuum diffusion bonding. The relationship between bonding parameters, and joint microstructure and shear strength was investigated. The results indicated that the diffusion of Al, Ti, Nb and V elements across bonding interface led to the formation of three reaction layers: B2/β layer and α₂ layer on the TC4 side, and α₂+B2/β layer on the Ti₂AlNb side. The bonding temperature determined the atomic activity, thus controlling the growth of reaction layers and influencing the shear strength of the joint. When the Ti₂AlNb alloy and TC4 alloy were bonded at 950 °C for 30 min under 10 MPa, the shear strength of the joint reached the maximum of 467 MPa. The analysis on the fracture morphology showed that the fracture occurred within the B2/β layer and the fracture model was ductile rupture. Meanwhile, the formation mechanism of the Ti₂AlNb/TC4 joint was discussed in depth.     

Brazing of TiBw/TC4 composite and Ti60 alloy using TiZrNiCu amorphous filler alloy

TiB_w/TC4 composite was brazed to Ti60 alloy successfully using TiZrNiCu amorphous filler alloy, and the interfacial microstructures and mechanical properties were characterized by SEM, EDX, XRD and universal tensile testing machine. The typical interfacial microstructure was TiB_w/TC4 composite/β-Ti + TiB whiskers/(Ti, Zr)₂(Ni, Cu) intermetallic layer/β-Ti/Ti60 alloy when being brazed at 940 °C for 10 min. The interfacial microstructure evolution was influenced strongly by the diffusion and reaction between molten fillers and the substrates. Increasing brazing temperature decreased the thickness of brittle (Ti, Zr)₂(Ni, Cu) intermetallic layer, which disappeared finally when the brazing temperature exceeded 1020 °C. Fracture analyses indicated that cracks were initialized in the brittle intermetallic layer when (Ti, Zr)₂(Ni, Cu) phase existed in the brazing seam. The maximum average shear strength of joints reached 368.6 MPa when brazing was conducted at 1020 °C. Further increasing brazing temperature to 1060 °C, the shear strength was decreased due to the formation of coarse lamellar (α+β)-Ti structure.     

Cold metal transfer welding–brazing of magnesium to pure copper

Magnesium alloy AZ31B and pure copper T2 were lapped and joined by cold metal transfer (CMT) welding–brazing method by AZ61A magnesium alloy wire with a 1·2 mm diameter. Results indicated that a satisfied Mg/Cu CMT welding–brazing joint was obtained in the stable welding processes with no spatter. The joint was composed of Mg–Mg welding joint formed between the Mg weld metal and the Mg base metal, and Mg–Cu brazing joint formed between the Mg weld metal and the local molten Cu base metal. The microstructure and the intermetallic compound (IMC) distribution were inspected and analysed in detail. The interfacial reaction layers of the brazing joint consisted of Mg₂Cu, Al₆Cu₄Mg₅, MgCu₂ and Mg₁₇Al₁₂ IMCs. The tensile shear strength of the Mg/Cu CMT welding–brazing joint could reach 172·5 N mm^?1. In addition, two different fracture modes were observed: at the fusion zone and at the brazing interface.     

Microstructure and mechanical properties of diffusion bonded joints between titanium and stainless steel with copper interlayer

Abstract

The solid state joining of titanium to stainless steel with copper interlayer was carried out in the temperature range of 850–950°C for 7·2 ks in vacuum. The interface microstructures and reaction products of the transition joints were investigated with an optical microscope and a scanning electron microscope. The elemental concentration of reaction products at the diffusion interfaces was evaluated by electron probe microanalysis. The occurrence of difference in intermetallics at both interfaces (SS/Cu and Cu/Ti) such as CuTi₂, CuTi, Cu₄Ti₃, χ, FeTi, Fe₂Ti, Cr₂Ti, α-Fe, α-Ti, β-Ti, T₂(Ti₄₀Cu_60?xFe_x; 5<x<17), T₄(Ti₃₇Cu_63?xFe_x; 5<x<7) and T₅(Ti₄₅Cu_55?xFe_x; 4<x<5) has been predicted from the ternary phase diagrams of Fe–Cu–Ti and Fe–Cr–Ti. These reaction products were detected by X-ray diffraction technique. The maximum tensile strength of ～91% of Ti strength and shear strength of ～74% of Ti strength along with ～ 7·2% ductility were obtained for the joint bonded at 900°C due to better coalescence of mating surfaces. At a lower joining temperature of 850° C, bond strength is poor due to incomplete coalescence of the mating surfaces. With an increase in the joining temperature to 950°C, a decrease in bond strength occurred due to an increase in the volume fraction of brittle Fe–Ti base intermetallics.     

Low-Temperature Interface Reaction Between Titanium and the Eutectic Silver-Copper Brazing Alloy

Reaction zones formed at 790 °C between solid titanium and liquid Ag-Cu eutectic alloys (pure and Ti-saturated) have been characterized. When pure Ag-Cu eutectic alloy with 40 at.% Cu is used, the interface reaction layer sequence is: αTi/Ti₂Cu/TiCu/Ti₃Cu₄/TiCu₄/L. Because of the fast dissolution rate of Ti in the alloy, the reaction zone remains very thin (3-6 μm) whatever the reaction time. When the Ag-Cu eutectic alloy is saturated in titanium, dissolution no longer proceeds and a thicker reaction zone with a more complex layer sequence grows as the reaction time increases. Four elementary chemical interaction processes have been identified in addition to Ti dissolution in the liquid alloy. These are growth of reaction layers on Ti by solid state diffusion, nucleation and growth from the liquid of TiCu₄, isothermal solidification of silver and, finally, chemical conversion of the Cu-Ti compounds by reaction-diffusion in the solid state. A mechanism combining these processes is proposed to account for the constitution of Ti/Ag-Cu/Ti joints brazed at 780-800 °C.