Investigation on reactive diffusion bonding of SiCp/6063 MMC by using mixed powders as interlayers

Mixed Al–Si, Al–Cu and Al–Si–SiC powders were used as interlayers to reactive diffusion bond SiCp/6063 MMC. The microstructure and the effects of bonding parameters on the shear strength of SiCp/6063 MMC joints were investigated. The results show that SiCp/6063 MMC joints bonded by using the interlayers of mixed Al–Si, Al–Cu powders have a dense joining layer of high quality. The mass transfer between the bonded materials and the interlayers during bonding leads to the hypoeutectic microstructure of the joining layers. Using mixed Al–Si–SiC powder as an interlayer, SiCp/6063 MMC can be reactive diffusion bonded by a composite joint. Because of the SiC segregation, however, there are a number of porous zones in the joining layer. This is responsible for the low shear strength of the joints, even lower than those reactive diffusion bonded by using the interlayers of mixed Al–Si and Al–Cu powders. Ti added in the interlayer obviously improves the joint strength reactive diffusion bonded by using the mixed Al–Si–SiC powder.     

Joining of SiCp/Al composites by insert powder layers

Mixed Al-Si, Al-Si-SiC and Al-Si-W powders were employed as insert layers to reactive diffusion bond SiCp/6063 MMC. The results show that SiCp/6063 MMC joints bonded by the insert layer of the mixed Al-Si powder have a dense joining layer with a typical hypoeutectic microstructure. Using mixed Al-Si-SiC powder as insert layer, SiCp/6063 MMC can be reactive diffusion bonded by a composite joint. Because of the SiC segregations, however, there are a number of porous zones in the joining layer, which results in the low shear strength of the joints, even lower than that of joints reactive diffusion bonded by the insert layer of mixed Al-Si powder. The W added into the insert layer of Al-Si-W nearly all reacts with Al to form intermetallic WAl12 during bonding. The reaction between the W and Al facilitates to form a dense joint of high quality, and the formed interrnetallic WAl12 has a reinforcing effect on the joints, which lead to the high shear strength of the joints. In general, under the condition of fixed bonding time （temperature）, the shear strengths of the joints increase as the bonding temperature （time） increases, but tend to a maximum at bonding temperature of 600℃ （time 90 min）.     

GH4141镍基合金的扩散连接工艺

对GH4141高温镍基合金的扩散连接进行了工艺研究，确定了扩散连接工艺参数对室温抗剪强度的影响，确定了获得优质接头的最佳工艺参数区间，即扩散连接温度r=990～1080℃，连接时间t=15～60min，连接比压力P=5～20MPa，选用Ni箔作为中间层，厚度为25um。通过SEM、EPMA和金相技术对接头微观组织进行了观察和分析。     

采用Al及Al-12Si中间层的AZ31B镁合金TLP接头的组织和性能

采用Al及Al-12Si为中间层对AZ31B镁合金进行过渡液相扩散焊,用环境扫描电镜及万能试验机测试并分析了接头组织与强度之间的关系。研究结果表明：采用Al作为中间层时,随着保温时间的增加,Al12Mg17金属间化合物含量降低,接头强度升高;采用Al-12Si作为中间层时,含硅相Mg2Si对焊缝的强化提高了接头强度,但保温时间过长时,Mg2Si偏聚于焊缝中心会降低接头性能。     

Fabrication of non-superconducting and superconducting joints of Ag/Bi-2223 tapes by diffusion bonding

Diffusion bonding of multifilamentary Ag/Bi-2223(Bi_2Sr_2Ca_2Cu_3O_x) superconducting tapes has been performed successfully.Three types of joints,namely,with silver interlayer (type I),bonded directly (type II),with Bi-2212(Bi_2Sr_2Ca_1Cu_2O_x) powder interlayer or with Bi-2223 powder interlayer (type III) were researched,respectively.The critical currents(I_C) of these joints were measured and microstructures of the joints were evaluated by scanning electron microscope (SEM).The result shows that type I is non-superconducting joint with very low resistance,and type II joint and type III (with Bi-2212 or Bi-2223) joints are both of superconducting property.By comparing,type II joint possesses most excellent superconductivity,type III joint with Bi-2223 powder interlayer takes the second place,and type III joint with Bi-2212 powder interlayer is least.     

Influence of diffusion bonding conditions on bonding strength of damping copper alloy to stainless steel

The experimental investigation of different tran sition metals was carried out in the diffusion bonding joints of Cu alloys (CuAlBe) to stainless stee l (1Cr18Ni9Ti). The microstructure of the joint was analyzed with microscopic examination, SEM, EPMA and X-ray diffraction. Following conclusions have been draw n: (1) The joint strength with the Ni interlayer was higher than that with Cu in terlayer when the welding parameters were same;(2)When Ni interlayer was thinner ,Al could interact with Ni and Fe,and the intermetallic compounds,such as Fe3A letc,were formed in the interface,which decreased the strength of the joints;(3 ) When the bonding temperature was higher,because of the diffusion of Cu in Ni being faster than Ni in Cu,a Kirkendall effect was produced,which also decreased the strength of the joints.     

V/Nb复合中间层热等静压扩散连接钢/钨接头的组织与性能

采用V/Nb复合中间层成功实现了钢/钨热等静压扩散连接,并对高温低压(1 050 ℃, 20 MPa)和低温高压(950 ℃, 100 MPa)条件下形成的接头界面结构及连接强度进行了探究. 结果表明,高温低压组和低温高压组接头均呈W/Nb/V/钢四层结构,抗剪强度分别为96.9 MPa和104.2 MPa,断裂位置均为无明显化学反应发生在Nb/V界面. 与高温低压组相比,降低连接温度并提高连接压强在一定程度上有助于形成高致密度的连接接头,但不能促进薄弱界面(Nb/V)的元素扩散并显著提高接头的连接强度.     

钴/镍复合中间层真空扩散连接钨与钢

以钴粉/镍箔为复合中间层,采用800,900和1 000 ℃等三种连接温度,加压10 MPa并保温120 min的工艺条件,对钨/钢真空扩散连接. 研究了接头的微观组织、成分分布、力学性能及断口特征. 结果表明,连接温度为800 ℃和900 ℃时,钨/中间层界面金属间化合物生成很少,对应接头抗剪强度分别为186 MPa和172 MPa,断口均位于钨母材中近界面的位置,为典型解理断裂形貌;当连接温度升至1 000 ℃时,钨/中间层界面生成厚度小于2 μm的连续金属间化合物层,接头抗剪强度降至115 MPa,断裂也发生在钨母材中近界面的位置,断口大部分区域为沿晶断裂特征.     

镁合金与铝合金的夹层扩散焊连接

采用锌夹层在356℃温度下对镁铝异种金属进行扩散焊连接,并对接头的微观组织和力学性能进行分析.结果表明,利用镁与锌原子互扩散形成低熔点共晶液相区,能够实现镁铝材料的可靠连接.镁铝焊接接头界面区由铝锌反应层、未充分扩散锌层、锌镁反应扩散层组成.铝基体侧铝锌反应层是固溶体层,镁基体一侧锌镁反应扩散层主要是过饱和的固溶体基体及弥散析出的中间相,该区的中间相成分为Mg2Zn11及MgZn2.锌夹层的加入可有效阻止镁铝之间的互扩散.锌夹层镁铝扩散焊接头抗剪强度远超过镁铝直接真空扩散焊接头的抗剪强度.断口观察及相分析表明,接头失效发生在锌镁反应扩散层.     

TLP bonding of alumina ceramic and 5A05 aluminum alloyusing Ag-Cu-Ti interlayer

In order to join alumina ceramic to 5A05 aluminum alloy and obtain the excellent airtightness of joints whose maximum service temperature is 623 K,transient liquid phase (TLP) bonding technique was investigated using Ag-Cu-Ti alloy as interlayer.The wetting experimental results confirm that Ti can react with alumina ceramic at 833 K by adding 2 wt.% Ti in Sn.But during bonding alumina ceramic and 5A05 aluminum alloy with Ag-Cu-Ti interlayer at 833 K,Ti preferentially reacts with Al and there is no reaction layer on alumina ceramic/Ag-Cu-Ti interface,which finally results in a poorly airtight joint.     

A two-step transient liquid phase diffusion bonding process of T91 steels

In this study,a two-step heating process is introduced for transient liquid phase( TLP) diffusion bonding for sound joints with T91 heat resistant steels. At first,a short-time higher temperature heating step is addressed to melt the interlayer,followed by the second step to complete isothermal solidification at a low temperature. The most critical feature of our new method is producing a non-planar interface at the T91 heat resistant steels joint. We propose a transitional liquid phase bonding of T91 heat resistant steels by this approach. Since joint microstructures have been studied,we tested the tensile strength to assess joint mechanical property. The result indicates that the solidified bond may contain a primary solid-solution,similar composition to the parent metal and free from precipitates. Joint tensile strength of the joint is not lower than parent materials. Joint bend's strengths are enhanced due to the higher metal-to-metal junction producing a non-planar bond lines.Nevertheless,the traditional transient liquid phase diffusion bonding produces planar ones. Bonding parameters of new process are 1 260 ℃ for 0.5 min and 1 230 ℃ for 4 min.     

以铜和Cu-Ti作为中间层的TiAl/GH3536扩散焊

采用铜箔和Cu-Ti合金作为中间层进行了TiAl和GH3536的扩散焊试验.以铜箔作为中间层在935℃/10 MPa/1 h参数下获得的焊缝组织以Ti（Cu,Al）2,AlCu2Ti和AlNi2Ti相为主,焊缝中存在裂纹.接头室温平均抗剪强度仅有31 MPa.以Cu-Ti合金作为中间层在935℃下采用三种不同参数进行了TiAl和GH3536的液相扩散焊试验.当加压3 MPa,保温10 min时,扩散焊缝中央还存在着宽度约5μm的残留相.保温时间延长至1 h,焊缝形成了较为均匀的分层组织,获得的接头室温抗剪强度最高,达180 MPa.增大压力至20 MPa,保温2 h获得的接头中出现AlNi2Ti相,接头平均室温抗剪强度下降至90 MPa.     

高2223相含量粉末扩散连接BSCCO带材

采用压制和高温烧结工艺获得了2223相含量达88.5%的粉末中间层,压制工艺有利于提高粉末中2223相的含量.用上述粉末实现了61芯BSCCO带材的超导扩散连接.结果表明,当连接温度为800℃、保温时间为2 h及压力为3 MPa时,接头平均超导连接效率CCRo可到达49.9%;粉末中2223相含量增加,接头连接效率提高.连接参数对接头显微组织的影响既明显又复杂.     

Influences of diffusion bonding process parameters on bond characteristics of Mg-Cu dissimilar joints

In many circumstances,dissimilar metals have to be bonded together and the resulting joint interfaces must typically sustain mechanical and/or electrical forces without failure,which is not possible by fusion welding processes.The melting points of magnesium(Mg)and copper(Cu)have a significant difference(nearly 400℃)and this may lead to a large difference in the microstructure and joint performance of Mg-Cu joints.However,diffusion bonding can be used to join these alloys without much difficulty.This work analyses the effect of parameters on diffusion layer thickness,hardness and strength of magnesium-copper dissimilar joints.The experiments were conducted using three-factor,five-level,central composite rotatable design matrix.Empirical relationships were developed to predict diffusion layer thickness,hardness and strength using response surface methodology.It is found that bonding temperature has predominant effect on bond characteristics.Joints fabricated at a bonding temperature of 450℃, bonding pressure of 12 MPa and bonding time of 30 min exhibited maximum shear strength and bonding strength of 66 and 81 MPa, respectively.     

直接扩散连接制备多芯Bi系超导带材超导接头

采用扩散连接方法对61芯Bi系高温超导带材(BSCCO)进行连接,研究了连接温度、保温时间、连接压力对接头超导电性的影响规律,并对超导接头的组织进行了微观分析.结果表明,连接温度对接头的超导性能影响较大,保温时间和连接压力在一定的范围内,对接头的超导性能影响不大;当连接温度为820 ℃,保温时间120 min,连接压力3 MPa时,接头获得最佳的超导电性能,接头的超导性能达到了原始母材的65.9%.微观分析表明,接头界面区域组织致密,主要由Bi-2223相和少量的Bi-2212相构成.     

Diffusion bonding of copper alloy to stainless steel with Ni and Cu interlayer

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Superplasticity and diffusion bonding of magnesium alloy ZK60

1 INTRODUCTIONRecently , the use of magnesium alloys asstructural materials has significantlyincreased,forits good damping capacity , di mension stability ,machinability and lowcasting costs . But magnesi-umalloys normally exhibit lowductility near roomtemperature because of their HCP structure .Therefore ,it is necessary to i mprove the ductilityof these alloys for their use as structural compo-nents[1 3].In manufacturing,superplastic forming is of-ten combined with diffusion bonding, w…     

TC4钛合金局部感应加热刚性拘束热自压扩散连接与机理分析

提出了一种新型扩散连接方法——局部感应加热刚性拘束热自压扩散(TSCB).利用TC4板材进行了实验,验证了局部感应加热刚性拘束热自压扩散方法的可行性.在实验基础上建立了感应加热刚性拘束热自压扩散过程热应力应变有限元分析模型,揭示了钛合金局部感应加热刚性拘束热自压扩散连接机理.实验结果表明,感应加热刚性拘束热自压扩散原理...     

镍箔中间层厚度对GH4099合金固相扩散焊质量的影响

采用2， 4和 10 μm 镍箔作为中间层，在1 120 ℃/4 MPa/60 min焊接条件下，对高温合金GH4099进行固相扩散焊. 采用SEM，EDS分析接头形貌演变、元素迁移，并利用拉伸试验测试其力学性能. 结果表明，添加镍中间层能促进界面的孔洞闭合. 随着镍层厚度由10 μm降低至2 μm，界面处出现晶粒共生现象，元素扩散更加均匀，焊缝析出较大尺寸的强化相，接头抗拉强度提高，2 μm中间层接头平均抗拉强度达到1 180 MPa. 但随着中间层减薄，接头性能对表面粗糙度敏感，拉伸过程中母材对中间层拘束作用使接头塑性变形受到抑制，断后伸长率反而降低.     

Effect of solidification mechanism on microstructure and mechanical properties of joint in TLP bonded Al2024‐T6 alloy

Abstract

Transient liquid phase (TLP) bonding of Al2024‐T6 alloy, using gallium (Ga) interlayer, has been investigated. Bonding process was carried out at 470°C for 6?min, and homogenising temperature and time were 495°C and 2?h respectively. Conventional TLP bonding using Ga interlayer was not an appropriate method for joining of Al2024. In this method, the boundary between two Al2024 specimens was not fully eliminated during bonding because of solidification with planar front. In addition, bonding zone was depleted of copper, and as a result, tensile and shear strength of joint decreased to 200 and 110?MPa respectively. TLP bonding under temperature gradient offered very good results in bonding of Al2024. In this method, solidification mechanism change from planar to dendritic, and tensile and shear strength of joint increased to about 460 and 220?MPa respectively. Microstructure of bonding zone changed basically by changing solidification mechanism.