SiCP/Al复合材料的真空扩散钎焊

文中采用Al/Cu/Al复合箔扩散钎焊SiC_P/Al复合材料,采用SEM,EDS,XRD分析接头界面组织,研究了钎焊温度对接头界面组织及力学性能的影响,并结合Al-Cu二元相图分析接头形成机制.结果表明,固定连接压力为1 MPa,保温时间为10 min,当钎焊温度从590℃升至640℃,接头界面产物由Al₂Cu+αAl共晶组织转变为断续的Al₂Cu金属间化合物,Al-Cu液相向两侧母材扩散的距离增加,接头的抗剪强度呈现先增大后减小的变化趋势.当钎焊温度为620℃,保温时间为10 min,连接压力为1 MPa时,接头的抗剪强度达到最大值69 MPa.     

基于Ti中间层的AZ31镁合金/6061铝合金电阻点焊研究

通过添加钛箔中间层,研究了镁/铝合金异种金属电阻搭接接头的微观组织与力学性能。研究结果表明,添加0.2mm厚度钛箔中间层可以大幅提高镁/铝异种金属电阻点焊接头的结合强度,接头的最大拉剪力随焊接电流的增大先增大后减小;当焊接电流为14kA时,最大拉剪力达到最大为2.2kN。铝钛界面处有TiAl₃生成,接头断裂在镁侧热影响区上,经过换算接头的剪切强度能够达到156MPa。通过SEM和EDS分析,添加钛中间层阻断了镁合金和铝合金的相互扩散,钛中间层阻碍了Mg-Al金属间化合物的生成,从而大大提高接头的结合强度。     

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.     

表面毛化WC-Co硬质合金与铝的真空扩散连接

采用机械方法对WC-Co硬质合金表面进行焊前毛化加工,然后采用BNi2钎料对毛化后的硬质合金表面进行预涂覆处理,最终利用毛化凸台在铝中的压入及界面元素的扩散反应实现WC-Co硬质合金与铝的真空扩散连接. 结果表明,接头界面结构为:Al/Al₃Ni+Al₃Ni₂+Al₅Co₂/Co-Ni(s.s)/W-Co-Ni/WC-Co. 随着预涂覆温度的升高,W-Co-Ni化合物相的体积增大,界面由平齐向不规则演变;随着扩散温度的提高,Al₃Ni+Al₃Ni₂+Al₅Co₂层厚度增加. 当工艺参数增加时,接头抗剪强度呈现出先升高后降低的变化趋势,特别是当预涂覆温度为1 050 ℃,扩散连接温度为575 ℃,保温时间为90 min时,接头室温抗剪强度达到最大值51 MPa,明显高于未毛化接头的抗剪强度.     

Analyzing the Effect of Diffusion Bonding Process Parameters on Bond Characteristics of Mg-Al Dissimilar Joints

The principle difficulty when joining magnesium (Mg)-aluminium (Al) lies in the existence of formation of oxide films and brittle intermetallic in the bond region. However, diffusion bonding can be used to join these alloys without much difficulty. Temperature, pressure, and holding time are the three main variables which govern the integrity of a diffusion bond. This paper focuses on the effect of these parameters on diffusion layer thickness, hardness and strength of AZ31B magnesium-AA2024 aluminium dissimilar joints. The experiments were conducted based on three factors, five-level, and central composite rotatable design with full replications technique. Empirical relationships were developed to predict diffusion layer thickness, hardness and strength using response surface methodology. From this investigation, it is found that bonding temperature has predominant effect on bond characteristics.     

TLP bonding of Ti-6Al-4V and Mg-AZ31 alloys using pure Ni electro-deposited coats

Transient liquid phase (TLP) bonding of Mg-AZ31 and Ti-6Al-4V alloys was performed using pure thin Ni electro-deposited coat interlayer (12 μm). The effect of bonding temperature, time and pressure on microstructural developments and subsequent mechanical properties across joint interface was studied at a temperature range from 500 to 540 °C, bonding time from 1 to 60 min and bonding pressure from 0 to 0.8 MPa. The mechanisms of bond formation varied across the joint region, with solid-state diffusion dominant at the Ti-6Al-4V interface and eutectic diffusion at the Mg-AZ31 interface. Joint microstructure was examined by scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). X-ray diffraction (XRD) was used to detect the formation of intermetallic phases at the fracture surface. The maximum joint shear strength of 61 MPa was obtained at a temperature of 520 °C, 20 min and at a bonding pressure of 0.2 MPa. This joint strength was three times the bond strength reported for joints made using adhesives and represents 50% of the Mg-AZ31 alloy shear strength.     

表面毛化不锈钢与纯铝的真空扩散连接

采用冷金属过渡技术(CMT)对不锈钢表面进行毛化,在其表面制备高度为3 mm、分布密度为9个/cm2的毛刺,毛刺中心横向及纵向间距均为3 mm. 研究其与纯铝进行真空扩散连接接头的界面组织和性能,分析不同保温时间对接头组织和性能的变化规律. 结果表明,在扩散连接温度为600 ℃,保温时间为60 min,压力为3 MPa的工艺条件下,表面毛刺刺入铝母材内部,使得表面氧化膜有效去除,接头形成连续的Fe₂Al₅+FeAl₃界面反应层,相比不锈钢与纯铝的直接真空扩散连接,接头拉剪强度显著提高. 此外,在扩散连接温度一定时,随保温时间的增加,反应层厚度增加,接头拉剪强度呈现先增大后减小的变化趋势.     

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.     

TiB2金属陶瓷与TiAl金属间化合物的扩散连接

对TiB2金属陶瓷与TiAl金属间化合物进行了扩散连接试验，研究了直接扩散连接和采用Ni为中间层进行扩散连接的接头界面结构及工艺参数对界面结构和连接性能的影响。直接扩散连接时，连接界面处生成了Ti(Cu，Al)2金属间化合物，采用Ni为中间层进行扩散连接时，界面处生成了单层TiAlNi2金属间化合物层和两层T1，Al，N2扩散层共三层结构。直接扩散连接时，连接温度T＝1223K，时间t=1．8ks，压力p＝80MPa时接头强度为103MPa；采用Ni为中间层时，连接温度T＝1273K，时间t=1．8ks，压力p=80MPa时接头强度为110MPa。     

Characterization of diffusion-bonded joint between Al and Mg using a Ni interlayer

Aluminum and magnesium were joined through diffusion bonding using Ni interlayer. The microstructure and mechanical performance of the Al/Ni/Mg joints at different temperatures was investigated by means of scanning electron microscope(SEM), electro-probe microanalyzer(EPMA), X-ray diffraction(XRD), Vickers hardness testing, and shear testing. The results show that the addition of Ni interlayer eliminates the formation of Mg–Al intermetallic compounds and improves the bonding strength of the Al/Mg joints. The Al/Ni/Mg joints are formed by the diffusion of Al, Ni and Mg, Ni. The microstructure at the joint interface from Al side to Mg side is Al substrate/Al–Ni reaction layer/Ni interlayer/Mg–Ni reaction layer/Mg substrate multilayer structure. The microhardness of the Mg–Ni reaction layer has the largest value of HV 255.0 owing to the existence of Mg_2Ni phase.With the increase of bonding temperature, the shear strength of the joints increases firstly and then decreases.The Al/Ni/Mg joint bonds at 713 K for 90 min, exhibiting the maximum shear strength of 20.5 MPa, which is greater than that of bonding joint bonded directly or with Ag interlayer. The fracture of the joints takes place at the Mg–Ni interface rather than the Al–Ni interface, and the fracture way of the joints is brittle fracture.     

Al-Si-Cu合金粉末扩散钎焊Al/Cu接头组织及性能

采用Al-Si-Cu合金粉末扩散钎焊铝铜异种金属,采用SEM,EDS和XRD分析接头微观组织结构,结合三元相图分析了接头形成机理,最后检测了接头力学性能.结果表明,在连接温度530℃,保温时间60 min,压力为1MPa时可形成均匀致密的接头,接头中存在大量条状和鱼骨状的Al-Si-Cu共晶组织,中间层与两母材结合界面处的组织结构不同,在靠近铜侧界面存在三种层状金属间化合物,其成分依次为Cu₃Al₂,CuAl和CuAl₂,在靠近铝侧界面存在一个扩散区,没有形成层状金属间化合物.接头的抗剪强度随保温时间的变化而变化,在保温60 min时达到35 MPa.     

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.     

Mg/Al脉冲加压扩散连接接头显微组织及力学性能

采用脉冲加压扩散连接工艺,实现了AZ31镁合金与5083铝合金的连接.借助扫描电镜、EDS、X射线衍射仪和显微硬度计等手段对接头的显微组织及力学性能进行了研究.结果表明,接头有镁合金基体、冶金反应层、扩散层和铝合金基体组成.焊缝中形成了Mg₂Al₃,AlMg和Al_0.56Mg_0.44金属间化合物.接头最高硬度值达3300 MPa.随着保温扩散时间的延长,接头的抗拉强度出现了先升高后降低的现象,最高接头强度达46 MPa,在断口中发现了部分韧窝,断口属于韧性和准解理混合断口.在镁合金和铝合金两侧,硬度变化区域出现不对称现象.     

有机溶剂保护对Al/Ni扩散连接的影响规律研究

采用有机溶剂保护实现了纯铝和纯镍的扩散连接。利用扫描电子显微镜、能谱分析以及X射线衍射等分析手段,确定了Al/Ni扩散连接接头典型的界面结构为Al/Al_3Ni_2/Ni。在扩散连接过程中利用有机溶剂防止铝表面发生二次氧化,相比直接扩散连接可得到更好的焊接质量。研究了连接温度对Al/Ni接头界面结构的影响规律,随着连接温度的升高各反应层厚度逐渐增加。当连接温度为490℃,连接时间为60 min,连接压力为2 MPa时,接头抗剪强度达到最大值,为17.83 MPa,比该工艺下直接扩散连接得到的焊接接头强度提高了约55%。     

连接条件对00Cr25Ni7Mo3N双相不锈钢扩散连接的影响

利用热模拟试验机并结合扫描电镜(SEM)对00Cr25Ni7Mo3N超级双相不锈钢的超塑扩散连接进行实验研究,对不同连接条件下的孔洞形貌、界面组织进行相应的分析。研究结果表明,超塑性扩散连接试样的界面结合强度随扩散连接压力的增大、表面质量的提高及连接时间的延长而增大。扩散连接在连接温度1100℃时,连接压力为10MPa～20MPa;待连接表面经精磨处理后,连接时间10min～20min的条件下,可实现焊合率为96%～98%的扩散连接,且连接试样的初始连接界面消失,界面孔洞基本闭合,界面剪切结合强度达到407MPa～413MPa。     

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.     

AZ31Mg/2A12Al爆炸复合板界面组织与性能

镁合金板上复合铝合金板对拓宽镁合金的使用范围具有重要意义.?采用爆炸焊接进行了镁合金板和铝合金板工艺试验,并制成镁合金和铝合金复合板.?使用光学显微镜、扫描电子显微镜观察焊后复合板结合界面处的微观形貌,分析了界面形成过程.?使用显微硬度计和剪切试验机测量了复合板结合界面处的硬度和抗剪强度.?结果表明,经爆炸焊接后,复合...     

采用冷喷涂铜涂层做中间层的镁合金与钢共晶接触反应钎焊工艺及接头性能

采用厚度为50 μm的冷喷涂铜涂层作为中间层,研究了连接温度和保温时间对AZ31B镁合金/钢异种金属接触反应钎焊接头剪切强度的影响规律.通过金相显微镜、扫描电镜（SEM）、X射线衍射仪（XRD）、显微硬度和剪切强度试验,研究了AZ31B镁合金/钢钎焊接头界面微观组织和力学性能.结果表明,当连接温度为530℃,保温时间为60 min时,接头剪切强度达到最大值36.9 MPa.AZ31B镁合金/钢钎焊接头界面反应产物主要为Mg₂Cu,α-Mg固溶体和Mg-Cu-Al三元相.Mg-Cu-Al三元相的尺寸和分布,以及08F钢侧是否存在Mg₂Cu共晶相共同决定了接头的强度.由钎焊接头断口可知,最佳工艺参数下断裂方式为脆性断裂与韧性断裂的混合方式.     

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。     

Diffusion bonding of titanium alloy to tin-bronze

The vacuum diffusion bonding of titanium alloy to tin-bronze has been studied and the feasibility and appropriate processing parameters have been investigated. The maximum tensile strength of the joints is bonded joint has been observed by SEM, X-ray and EPMA, and the main factors affecting diffusion bonding have been analyzed. The intermetallic compounds Ti2Cu and TiCu were formed near the interface. The width and quantity of the intermetallic compound increases with the increase of the bonding time. The formation of the intermetallic compounds results in embrittlement of the joint and the poor joint properties.