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.     

保温时间对Mg/Cu共晶反应钎焊连接的影响

采用共晶钎焊工艺对Mg/Cu异种材料进行连接,研究了不同保温时间对接头微观组织及力学性能的影响.结果表明,在焊接温度为500℃、保温时间为30 min、焊接压力为2MPa的工艺下,焊接接头最高抗拉强度为54 MPa.     

镀银铜箔平行微隙电阻焊接头组织与性能

研究了0.1 mm厚镀银铜箔与纯铜箔平行微隙电阻焊接头的微观组织和力学性能,分析了不同参数对接头力学性能的影响,利用扫描电子显微镜对典型接头界面处的微观组织特征进行了分析. 结果表明,焊点连接面处组织致密;连接面由富银相和富铜相组成的两相区和只有富铜相的单相区组成,焊接温度达到了银的熔点,其连接机理与钎焊类似;试验所用参数范围内,焊点的最大剪切抗力达到了59 N,焊接功率和焊接时间对焊点性能的影响较大,而电极压力的影响较小.     

连接压力对管道瞬时液相连接接头组织性能的影响

把锅炉用20钢管在开放式管道瞬时液相扩散焊机上进行连接,采用氩气保护,焊接温度1180℃、保温时间3min、中间层材料选用非晶箔BNi2,通过改变连接压力,研究其对连接接头组织性能的影响.结果表明,当连接压力为4MPa时,所得连接接头的性能良好,满足要求.     

BNi68CrWB钎焊GH648/K42异种高温合金接头的组织与性能

采用BNi68CrWB钎料粉末对K24和GH648异种高温合金进行钎焊连接,分析了钎焊温度、保温时间、装配间隙等钎焊工艺参数对接头组织和性能的影响规律.结果表明,在钎焊接头可观察到三个特征组织区域:共晶区、等温凝固区和扩散区;钎焊温度过高,接头内部W-Cr-Ni脆性相增多,接头性能下降.保温时间延长可以促进钎料与母材之间元素的扩散,有利于获得均匀的固溶体组织,接头强度提高,但时间过长,性能略有下降.钎焊间隙在0.05~0.15 mm范围,钎焊温度1 150℃,保温时间30 min所得接头性能较高,约600 MPa.     

高温合金GH4169真空扩散连接工艺

采用真空直接扩散以及加镍中间层对高温合金GH4169进行了连接,阐述了扩散连接工艺参数对接头界面和接头力学性能的影响,以孔隙的多少作为评价指标来说明工艺参数对接头的影响.GH4169的直接扩散连接,升高加热温度、延长保温时间和增大连接压力均会不同程度的使界面的孔隙数目减少、尺寸变小.连接温度1 100℃,保温时间90 min,连接压力40 MPa时,扩散孔隙基本消失,接头平均抗拉强度达到658MPa.采用镍中间层对GH4169进行扩散连接,接头塑性得到改善,接头抗拉强度得到明显提高;连接温度990℃,保温时间75 min,连接压力15 MPa时,接头抗拉强度达到840 MPa.     

连接参数对Bi系(BSCCO)超导带材扩散连接接头性能的影响

采用高温直接加压退火工艺扩散连接61芯Bi系高温超导带材。研究了835℃连接温度下接头搭接长度、搭接区窗口的台阶数、保温时间对接头结合界面特征及其超导电性的影响。结果表明,连接参数对接头超导电性Ic影响明显,超导电性低的接头其超导芯结合界面处有未焊合迹象,母材经过835℃扩散连接热循环后超导电性显著降低。     

FeCrAl合金真空扩散焊焊接工艺与性能

采用真空扩散焊接方法对FeCrAl合金薄板进行了搭接焊.研究了扩散焊焊接工艺参数对接头质量的影响.在金相显微镜下对接头微观组织进行了观察,采用INSTRON1185万能拉伸试验机对接头试样的拉伸性能进行了测定.试验结果表明,焊接温度、焊接压力和保温时间对接头质量有很大的影响.FeCrAl合金在不填加中间层的情况下即可获...     

纯锆中间层扩散连接TC4钛合金的接头组织与力学性能

采用纯Zr作中间层实现了TC4钛合金的扩散连接。通过扫描电镜(SEM)、能谱分析(EDS)、X射线衍射(XRD)等方法分析了接头界面的微观组织,研究了扩散连接工艺参数对接头界面组织及力学性能的影响。结果表明,界面处生成了成分均匀、连续的钛锆固溶体扩散层,同时扩散层中含有大量板条状的α′-Ti(钛马氏体)相;随着连接温度的升高和保温时间的延长,扩散层的厚度逐渐增加,接头室温抗剪强度呈现出先升高后降低的趋势;当连接温度为800℃、保温时间为40 min、连接压力为5 MPa时,接头室温抗剪强度最高,达到190 MPa。     

TB2钛合金扩散连接与分形维数

在不同温度、压力、保温时间下对TB2 钛合金进行了扩散连接实验 ,利用SEM观察了扩散连接接头断口形貌并进行了分形维数计算 ,通过剪切实验得到了不同条件下的扩散连接接头的剪切强度。结果表明 ,连接温度、保温时间、连接压力对TB2 钛合金扩散连接接头的剪切强度和分形维数都有影响。剪切强度和分形维数呈正相关 ,工艺参数为扩散连接温度 85 0℃ ,保温时间 30min ,连接压力 5MPa时接头的剪切强度最高 (890MPa) ,同时 ,表面分形维数最大 (2 .2 3)。     

保温时间对20钢管道瞬时液相扩散连接的影响

在开放式管道瞬时液相扩散焊机上进行20钢管的TLP连接.采用氩气保护,连接温度1180℃、连接压力4MPa,中间层材料选用非晶箔BNi_2,通过改变保温时间,研究其接头显微组织的变化及降熔元素的扩散情况.结果表明,当保温时间为2和2.5min时,降熔元素Ni、Cr扩散不充分;当保温时间增大到3min时,中间层中Ni、Cr扩散充分,达到比较理想状态,从而获得性能良好的连接接头.     

Optimizing Diffusion Bonding Parameters in AA6061-T6 Aluminum and AZ80 Magnesium Alloy Dissimilar Joints

The main difficulty when joining magnesium (Mg) and aluminum (Al) alloys by fusion welding lies in the formation of oxide films and brittle intermetallic in the bond region which affects the integrity of the joints. However, diffusion bonding is a suitable process to join these two materials as no such characteristic defects are produced at the joints. The diffusion bonding process parameters such as bonding temperature, bonding pressure, holding time, and surface roughness of the specimen play a major role in determining the joint strength. In this investigation, an attempt was made to develop empirical relationships to predict the strengths of diffusion bonded AZ80 magnesium and AA6061 aluminum alloys dissimilar joints from the process parameters based on central composite factorial design. Response surface methodology was applied to optimize the process parameters to attain the maximum shear strength and bonding strength of the joint. From this investigation, it was found that the bonds produced with the temperature of 405.87?°C, pressure of 7.87?MPa, holding time of 29.02?min and surface roughness of 0.10???m exhibited maximum shear strength and bonding strength of 57.70 and 76.90?MPa, respectively. The intermetallic formation at the interface was identified.     

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.     

Effect of bonding conditions on joints of 5052Al and 6063Al in pulsed electric current bonding

Recent reports on sintering and bonding using the pulsed electric current bonding process indicate that the metals are subjected to Joule heating due to the electrical resistance at the contact points. However, the influence of bonding conditions on local heating phenomena and joint quality remains unclear. In this study, the effects of bonding conditions (bonding temperature, pressure, surface roughness, interlayer, electric current wave and so on) on joint efficiency are investigated using 5052A1 and 6063A1 in pulsed electric current bonding.

The joint strength of 5052A1 and 6063A1 are improved using 2024A1 as the interlayer between the bonding interfaces. The joints with the 2024A1 powder as the interlayer are stronger than ones with 2024A1 plate, and are as strong as the base metal. The improvements of the joints depend on effective heat generation at the bonding interface due to the electrical resistance. It is 0.08 g (thickness: 0.04 mm), enough for the amount of powder between the bonding interfaces. The dispersion of the powder from the joints does not occur under various conditions.

The surface roughness and electric current wave (direct current, duty ratio, pulse frequency) have no effect on the joint strength. With the increase of bonding temperature and pressure, the deformation of the joints increases. Then bonding temperature and pressure have to be selected to prevent a big deformation of joint configuration.     

低真空条件下铝基复合材料扩散焊接工艺

以Al2O3p/6061Al铝基复台材科为对象．研究了在低真空条件下的直接扩散焊接和6061Al铝箔作为中间层的扩散焊接工艺。分析了焊接温度．保温时间与不同焊接工艺所得接头微观组织及强度的关系。同时．分析了低真空度和夹具对接头性能的影响。试验结果表明．两种焊接工艺所得接头强度随温度变化的规律以600℃和640℃为界分为三个阶段．并且随保温时间的延长有所提高。在较高的温度下．压力和液态金属的作用促使氧化膜破碎,有利于接头强度的提高。     

High temperature diffusion induced liquid phase joining of a heat resistant alloy

Transient liquid phase bonding (TLP) of a nickel base superalloy, Waspaloy, was performed to study the influence of holding time and temperature on the joint microstructure. Insufficient holding time for complete isothermal solidification of liquated insert caused formation of eutectic-type microconstituent along the joint centerline region in the alloy. In agreement with prediction by conventional TLP diffusion models, an increase in bonding temperature for a constant gap size, resulted in decrease in the time, t_f, required to form a eutectic-free joint by complete isothermal solidification. However, a significant deviation from these models was observed in specimens bonded at and above 1175 °C. A reduction in isothermal solidification rate with increased temperature was observed in these specimens, such that a eutectic-free joint could not be achieved by holding for a time period that produced complete isothermal solidification at lower temperatures. Boron-rich particles were observed within the eutectic that formed in the joints prepared at the higher temperatures. An overriding effect of decrease in boron solubility relative to increase in its diffusivity with increase in temperature, is a plausible important factor responsible for the reduction in isothermal solidification rate at the higher bonding temperatures.     

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.     

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…     

保温时间对置氢TC4真空钎焊界面结构及连接强度的影响

采用纯铝箔做中间层,真空连接普通TC4钛合金以及氢的质量分数分别为0.1%,0.3%,0.5%置氢TC4钛合金.利用扫描电镜、X射线衍射分析仪、能谱分析仪对接头界面组织进行分析,并进行接头压剪强度试验.结果表明,当保温时间为45 min时,连接接头组织由两层组成;而当保温时间足够长,达到90 min时,接头完全由TiAl3金属间化合物层组成.不同保温时间下接头的抗剪强度有明显的差别,且随保温时间的延长而下降后.而在相同的工艺参数下,置氢TC4钛合金连接强度明显高于普通TC4钛合金.