不同钎料对Ti3Al基合金钎焊接头强度及界面微观组织的影响

研究了Ti3Al基合金真空钎焊及接头组织性能;分析了不同钎料对接头界面组织和剪切强度的影响,初步优选了钎料,优化了钎焊连接规范参数;利用电子探针、扫描电镜和X射线衍射等方法对接头进行了定性和定量分析.结果表明:采用NiCrSiB钎料连接时,在界面处有金属间化合物TiAl3、AlNi2Ti和Ni基固溶体生成,TiAl3和AlNi2Ti的生成降低了接头的剪切强度;采用TiZrNiCu钎料连接时,在界面处有金属间化合物Ti2Ni、Ti(Cu,Al)2和Ti基固溶体生成,Ti2Ni和Ti(Cu,Al)2的形成降低了接头的剪切强度;采用AgCuZn钎料连接时,在界面处生成TiCu、Ti(Cu,Al)2和Ag基固溶体,TiCu和Ti(Cu,Al)2的生成是降低接头剪切强度的主要原因;采用CuP钎料连接时,在界面处生成了Cu3P、TiCu和Cu基固溶体,CuaP和TiCu使接头的剪切强度降低;对于NiCrSiB钎料,当连接温度为1 373 K,连接时间为5 min时,接头的剪切强度最高为219.6 MPa对于TiZr-NiCu钎料,当连接温度为1 323 K,连接时间为5 min时,接头的最高剪切强度为259.6 MPa;对于AgCuZn钎料,当连接温度为1 173 K,连接时间为5 min时,接头的最高剪切强度为125.4 MPa;对于CuP钎料,当连接温度为1 223 K,连接时间为5 min时,接头的最高剪切强度为98.6 MPa;采用TiZrNiCu钎料连接Ti3Al可获得最大接头强度.     

Al/Cu感应钎焊接头组织及性能研究

以某型汽车车载制冷系统为研究背景,采用Zn-22Al钎料配合Cs F-Al F_3钎剂通过感应钎焊的方法实现了Al/Cu的连接。研究结果表明,Al/Cu钎焊接头的Cu侧界面处主要由Al_4Cu_9和Al_2Cu_3金属间化合物组成,没有脆性Al_2Cu金属间化合物生成。钎焊接头抗剪切强度高达72 MPa,Al/Cu接头拉伸断裂于Cu侧界面处,呈现出典型的解理断裂形式。其研究结果能够为车载制冷系统及相近领域提供参考。     

真空热压铝和铜的固态连接(英文)

在温度623~923K下采用真空热压扩散连接铝和铜,具体工艺为在预置温度下,变形率为0.2mm/min时热压缩10min,再在炉冷过程中,以0.2mm/min成型10min。通过界面分析可以看出,合适的扩散连接温度为823K,在扩散过程中产生了3种主要的金属间化合物层,分别为Al2Cu、AlCu+Al3Cu4和Al4Cu9。3种化合物层的局部硬度分别为(4.97±0.05)、(6.33±0.00)、(6.06±0.18)GPa。     

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。     

Ti-Nb作缓冲层的TiC金属陶瓷/不锈钢脉冲加压扩散连接

采用Ti-Nb中间层对TiC金属陶瓷和不锈钢06Cr19Ni10进行了脉冲加压扩散连接,以实现缩短焊接时间并缓解界面产物对接头的有害作用的目的。连接温度890℃,脉冲压力2~10MPa工艺条件下,在4~12min时间内即实现了陶瓷与不锈钢的有效连接,与传统扩散焊相比连接时间大幅缩短。对接头进行显微组织表征发现在反应界面处存在溶解了少量Nb的σ相以及溶解了Ni的α β-Ti固溶体。在连接时间为10min时得到了最大的剪切强度110MPa。在剪切载荷下,接头沿着剩余的Ti/α β-Ti界面扩展至陶瓷内部断裂。结果表明,脉冲加压扩散连接能在一定程度上缩短焊接时间,中间层Ti/Nb的合理选择能很好的抑制了有害的金属间化合物的生成。     

Ti-Nb作缓冲层的TiC金属陶瓷/不锈钢脉冲加压扩散连接（英文）

采用Ti-Nb中间层对TiC金属陶瓷和不锈钢06Cr19Ni10进行了脉冲加压扩散连接,以实现缩短焊接时间并缓解界面产物对接头的有害作用的目的。连接温度890℃,脉冲压力2~10 MPa工艺条件下,在4~12 min时间内即实现了陶瓷与不锈钢的有效连接,与传统扩散焊相比连接时间大幅缩短。对接头进行显微组织表征发现在反应界面处存在溶解了少量Nb的σ相以及溶解了Ni的α+β-Ti固溶体。在连接时间为10 min时得到了最大的剪切强度110 MPa。在剪切载荷下,接头沿着剩余的Ti/α+β-Ti界面扩展至陶瓷内部断裂。结果表明,脉冲加压扩散连接能在一定程度上缩短焊接时间,中间层Ti/Nb的合理选择能很好的抑制有害的金属间化合物的生成。     

CuNi复合中间层对Mg/Al扩散焊接接头组织及力学性能的影响

采用真空扩散焊接的方法获得了Mg/CuNi/Al扩散焊接接头。采用万能试验机测试焊接接头剪切强度,通过SEM,EPMA,XRD对焊接接头的显微结构和物相组成进行了分析。结果表明,Mg/CuNi/Al扩散焊接接头剪切强度随焊接温度和保温时间的增加先增加后减小,焊接温度440℃,保温时间90 min时,接头剪切强度最大值达到22.4 MPa。焊接接头主要由Al3Mg2致密组织层、Al12Mg17针状组织层、Al12Mg17和α-Mg网状组织层组成,Cu、Ni富集于网状组织层中。Mg/CuNi/Al扩散焊接接头断口主要由Al3Mg2、Al12Mg17、AlCu3、Al2Cu和Al7Cu23Ni化合物组成,断裂方式以脆性断裂为主。     

热喷涂巴氏合金中间层瞬间液相连接Ti-6Al-4V和Al 2024合金（英文）

研究热喷涂辅助瞬间液相(TLP)扩散连接Ti-6Al-4V和Al 2024合金,在铝基体上热喷涂80μm厚的巴氏合金作为中间层。热喷涂会产生粗糙清洁的表面,使得接头强度更高。采用的优化参数为:连接温度580°C,保温时间30和60min。显微组织观察和XRD衍射谱证明在Al焊缝处形成Al_2Cu、Al_2Cu Mg、Cu_3Ti、Ti Al_3、Ti Al和Mg2_Sn金属间化合物。另一方面,在Ti合金一侧形成Ti_3Al、Sn_3Ti_5和Ti_3Sn金属间化合物。随着连接时间从30 min增加到60 min,尽管巴氏合金中间层没有被完全消耗,但是其剩余厚度下降到大约15μm。研究表明,在60 min较长连接时间下,接头的剪切强度达到57 MPa的较高值。     

液-固体积比对消失模铸造Al/Cu双金属界面组织性能的影响

研究液固体积比对消失模铸造Al/Cu双金属界面组织和性能的影响,并对Al/Cu双金属界面的形成机理进行讨论。结果表明:液固体积比为3:1时Al/Cu双金属材料无法形成有效的冶金结合,当液固体积比超过5:1时,Al/Cu双金属材料连接区域部分位置开始发生冶金结合;在发生冶金反应的情况下,Al/Cu双金属界面面均由Al4Cu9层,AlCu层,Al2Cu层和共晶反应层4层组成;随液固体积比增大,由于凝固时间延长和铜基体的溶解增加的共同作用,共晶反应层组织出现先粗大后细化的变化。Al/Cu界面层的硬度在140~190HV之间,未呈明显的规律性,随着液固体积比的增大,Al/Cu双金属材料的剪切强度先增加后减小,并在在7:1时达到最大值(81 MPa),且均从金属间化合物(IMCs)层发生断裂。     

Al-Si合金瞬间液相扩散连接接头组织与力学性能

采用扫描电镜、X射线衍射、能谱仪及电子拉伸试验机等测试方法研究了Cu箔作中间层瞬间液相扩散连接(TLP)Al-Si合金接头的组织和力学性能.结果表明,Al-Si合金基体中的Al元素与中间层Cu元素发生共晶反应形成液相,而合金中的Si对Al与Cu的相互作用有一定的阻碍.接头组织主要由α-Al、单晶Si及金属间化合物(CuAl2和Al4Cu9)组成,而金属间化合物的数量随连接时间的增加而减少.剪切试样沿着界面/基体处断裂.当温度为560℃时,随着连接时间的增加,接头抗剪强度先增大后减小,在120 min时达到最大值70.2 MPa;接头塑性和韧性提高,断口表面形貌由脆性特征转变为脆性和韧性共存的混合型断裂特征.     

转速对6061铝合金/纯铜异种金属搅拌摩擦焊接头组织与性能的影响

采用搅拌摩擦焊技术对4 mm厚6061-T6铝合金和纯铜进行连接,研究转速对铝铜异种金属接头组织与力学性能的影响。结果表明,当焊接速度为30 mm/min、搅拌头转速在1 200~1 800 r/min的范围内,可以获得表面成形良好、无缺陷的铝铜异种金属接头。大量破碎的铜被搅入焊核区,形成了组织结构复杂的区域。通过EDS和XRD分析,在焊核区内发现了Al_2Cu、Al_4Cu_9和Al Cu金属间化合物。在界面处,铝和铜发生相互扩散形成金属间化合物层,随着转速的提高,化合物层逐渐变厚。由于晶粒细化、固溶强化作用以及金属间化合物的生成,异种接头的焊核区平均显微硬度值高于铝铜两侧平均硬度,并且在焊核区出现硬度峰值点。随着转速的增加,接头抗拉强度呈现先增大后减小的趋势,所得最优接头抗拉强度为183 MPa,达到铜母材的71.8%,断裂位置位于铝侧热影响区,断裂方式为韧性断裂。     

Cu和Al箔扩散结合界面相生长行为研究

采用等离子活化烧结方法实现了Cu箔和Al箔的固相扩散结合,考察了673～773K温度范围内界面金属间化合物(IMCs)层的生成过程和生长动力学。结果表明:界面IMCs生成过程主要包括物理接触、IMCs形核、IMCs沿界面相连和IMCs层连续增厚4个阶段;界面主要由Al4Cu9、AlCu和Al2Cu层构成;各层厚度与反应时间的关系均符合抛物线规律,表明IMCs生长动力学由体扩散所控制;各层生长速率常数与反应温度之间满足Arrhenius关系,且整个IMCs界面层以及Al4Cu9、AlCu和Al2Cu各单层的生长激活能分别为80.78、89.79、84.63和71.12kJ/mol。     

Effects of intermetallic compound on the electrical and mechanical properties of friction welded Cu/Al bimetallic joints during annealing

Al/Cu metal joints applied for the electrical connector was joined by the friction welding method to limit the formation of intermetallic compound under optimum friction welding condition. To guarantee the reliability of the Al/Cu joints in service requirement, the effects of the intermetallic compound layer on the electrical and mechanical properties have been investigated under various annealing conditions. Two kinds of intermetallic compounds layer were formed in the joints interface and identified by AlCu and Al₂Cu. The growth kinetic of these intermetallics during the annealing can be followed by volume diffusion process. The activation energy of Al₂Cu, AlCu and total intermetallic compound (AlCu + Al₂Cu) represented 107.5, 98.42 and 110.22 kJ/mol, respectively. A thicker intermetallic compound layers could seriously degrade the electrical resistivity and tensile strength. The electrical resistivity with 21 μm thickness of intermetallic compound was 45 μΩ cm and increased to be 85 μΩ cm with 107 μm of intermetallic compound. Tensile strength remarkably decreased from 85 MPa to near zero at the annealing condition of 773 K and 129.6 ks and fracture occurred through the intermetallic compound layers.     

Microstructure and Mechanical Properties of Dissimilar Double-Side Friction Stir Welds Between Medium-Thick 6061-T6 Aluminum and Pure Copper Plates

It is difficult to achieve Al/Cu dissimilar welds with good mechanical properties for medium-thick plates due to the inherent high heat generation rate at the shoulder-workpiece contact interface in conventional friction stir welding. Thus, double-side friction stir welding is innovatively applied to join 12-mm medium-thick 6061-T6 aluminum alloy and pure copper dissimilar plates, and the effect of welding speeds on the joint microstructure and mechanical properties of Al/Cu welds is systematically analyzed. It reveals that a sound Al/Cu joint without macroscopic defects can be achieved when the welding speed is lower than 180 mm/min, while a nonuniform relatively thick intermetallic compound (IMC) layer is formed at the Al/Cu interface, resulting in lots of local microcracks within the first-pass weld under the plunging force of the tool during friction stir welding of the second-pass, and seriously deteriorates the mechanical properties of the joint. With the increase of welding speed to more than 300 mm/min void defects appear in the joint, but the joint properties are still better than the welds performed at low welding speed conditions since a continuous uniform thin IMCs layer is formed at the Al/Cu interface. The maximum tensile strength and elongation of Al/Cu weld are, respectively, 135.11 MPa and 6.06%, which is achieved at the welding speed of 400 mm/min. In addition, due to the influence of welding distortion of the first-pass weld, the second-pass weld is more prone to form void defects than the first-pass weld when the same plunge depth is applied on both sides. The double-side friction stir welding is proved to be a good method for dissimilar welding of medium-thick Al/Cu plates.     

工艺参数对Al2O3/TC4合金接头界面组织及力学性能的影响

采用Cu＋B钎料分别在钎焊温度890～970℃,保温时间为10min;钎焊温度为930℃,保温时间0～30min条件下,钎焊A120,陶瓷与TCA合金．利用SEM,EDS和压剪试验研究接头界面组织及力学性能．结果表明,随钎焊温度升高或保温时间的延长,Ti2（Cu,Al）2O层增厚,紧邻其侧生成连续并增厚的Ti2（Cu,Al）,Ti2（Cu,Al）含量增加;Ti＋Ti2（Cu,Al）含量增加,尺寸变大,分布范围逐渐变宽并向TC4合金侧迁移,TCA合金侧过共析组织区变宽．钎焊温度低于950℃时,TiB晶须主要分布在Ti2Cu晶界处的AlCu2Ti上;当钎焊温度高于950℃时,AlCu2Ti相逐渐消失,TiB晶须主要分布于Ti2Cu上．当保温时间为10min,钎焊温度为950℃时,接头最大强度为96MPa;而当钎焊温度为930℃,保温时间为20min时,接头最大强度为83MPa．关键词：Al2O3陶瓷;TC4合金;钎焊参数;界面组织;抗剪强度     

Development of an 8090/3003 bimetal slab using a modified direct-chill casting process

A modified direct-chill (DC) casting method was used to prepare an 8090/3003 bimetal slab of aluminum alloys with consistent mechanical properties. The interface of the as-cast bimetal material was free of detrimental intermetallic compounds, which indicated excellent metallurgical bonding. A diffusion layer with an average thickness of approximately 80 μm was obtained due to the interdiffusion of Li, Mg, Cu and Mn at the bimetal interface. The average ultimate tensile strength of the as-cast bimetal slab was 101 MPa, and all fractures occurred on the side of the softer 3003 alloy. T6 treatment was performed on the bimetal slab to investigate the response of the slab to heat treatment. The Vickers hardness of the 8090 side increased by 30% after T6 treatment, reaching 153 HV. The Vickers hardness of the interface layer also increased from 70 HV to 89 HV. The solution strengthening was considered to make the primary contributions on the hardness improvement of the bimetal slab at the interface after T6 treatment.     

焊丝成分对铝/铜激光熔钎焊接头组织和性能的影响

通过添加Zn-Al焊丝成功实现了2A16铝合金/T2铜异种材料的激光熔钎焊连接,并采用扫描电子显微镜和能谱仪对接头的微观组织进行表征,同时,研究了Zn-2％Al,Zn-5％Al和Zn-10％Al?3种焊丝对接头成形、微观组织以及力学性能的影响.结果表明,铝/铜激光熔钎焊接头主要由CuZn相,Al2Cu相,Al4Cu9相...     

Effects of Insert Metal Type on Interfacial Microstructure During Dissimilar Joining of TiAl Alloy to SCM440 by Friction Welding

Although the welding zone of direct bonding between a TiAl alloy and SCM440 can be obtained by friction welding, martensitic transformation and the formation of intermetallic compounds (IMCs) and cracks result in a lower tensile strength of the joints relative to those of other welding techniques. Insert metals were used as a buffer layer to relieve stress while increasing the bond strength. In this study, the microstructure and mechanical properties on welded joints of a TiAl alloy and SCM440 with various insert metals, were investigated. The TiAl/Cu/SCM440 and TiAl/Ni/SCM440 joints were fabricated using a servo-motor-type friction welding machine. As a result, it was confirmed that the formation of a welding flash was dependent on the insert metal type, and the strength of the base metal. At the TiAl/Cu/SCM440 interface, the formation of IMCs CuTiAl and Cu₂TiAl was observed at TiAl/Cu, while no IMC formation was observed at Cu/SCM440. On the other hand, at the TiAl/Ni/SCM440 interface, several IMCs with more than 100 μm thickness were found, and roughly two compositions, viz., Ti₂NiAl₃ and TiNi₂Al, were observed at the TiAl/Ni interface. At the Ni/SCM440 interface, 10 μm-thick FeNi and others were found.     

Microstructural characterization and mechanical properties of aluminum 6061-T6 plates welded with copper insert plate (Al/Cu/Al) using friction stir welding

Friction stir welding was used to join two aluminum 6061-T6 plates with an insert of a pure copper plate (Al/Cu/Al), and then the influence of the copper insert on the joint performance was studied. The dissimilar welding results were also compared with AA 6061 friction stir welds produced without copper insert (Al/Al). Optical and scanning electron microscopes were used for the microstructural observations of the welded samples. X-ray diffraction analysis was used to analyze phase component of the Al/Cu/Al specimen. A defect-free joint was observed for the Al/Cu/Al joint at a rotational speed of 950 r/min and a welding speed of 50 mm/min. Microstructural observation of the weld nugget zone (WNZ) demonstrates the formation of composite-like structure which promotes metallurgical bonding of aluminum and copper. XRD results show the formation of intermetallic compounds (IMCs), such as Al₄Cu₉ and Al₂Cu. Furthermore, it was observed that the hardness of the weld with the Cu insert plate is higher than that of other samples due to more dislocation density and a distinct rise in hardness values was observed due to the presence of IMCs. The ultimate tensile strength of the joint with copper insert plate is higher than that of the other sample due to the strong metallurgical bonding between Al and Cu.