扩散连接接头金属间化合物新相的形成机理

扩散连接接头中界面区脆性金属间化合物相的出现往往会造成接头性能的恶化,因此研究并建立接头界面区金属间化合物相的生成和成长行为的数学模型对扩散连接过程有非常重要的理论及现实意义。本文根据扩散理论,指出界面处生成相的动力学驱动力限决于扩散偶中组元自身的特性,生成机的组元及比例应按原子扩散通量比优先生成,本文从动力学及热力学角度出发,提出了多组元扩散偶界面处的金属间化合物生成相原则：通量-能量原则;并以钛/镍/钢扩散接接头为例,证明钛/镍界面处金属间化合物相的生成规律为Ni/TiNi3/TiNi/Ti2Ni/Ti。提出,通量-能量能力相当的两种或多种金属间化合物有可能同时形核篚,接头界面处会形成混合的金属间化合物。     

TC4钛合金与Al6061铝合金热等静压扩散连接接头的界面特征及力学性能

对TC4钛合金和Al6061铝合金的异种金属进行了热等静压扩散连接实验,研究了TC4/Al6061连接接头的界面特征、形成机制和力学性能,并通过热力学分析解释相关实验现象。结果表明,热等静压扩散连接及后续退火处理后,两侧母材元素发生了明显的互扩散,其中Si、Mg元素在化学势驱动力作用下分别富集于扩散过渡区和Al侧界面。接头界面发生冶金反应生成TiAl₃、TiAl、Ti₃Al等金属间化合物,通过有效生成热模型计算表明TiAl₃相优先生成。硬度实验表明界面生成的Ti-Al金属间化合物具有较高的硬度。拉伸实验显示接头最大抗拉伸强度达到了144 MPa。     

Impulse Pressuring Diffusion Bonding of Titanium to Stainless Steel Using a Copper Interlayer

采用Cu作中间层对工业纯钛和1Cr18Ni9不锈钢进行了脉冲加压扩散连接。在连接温度850 ℃,脉冲压力8~20 MPa工艺条件下,在120~180 s时间内即实现了钛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。在Ti/Cu界面生成了大量的Ti-Cu金属间化合物;而在Cu/不锈钢界面只生成了Cu在奥氏体不锈钢中的固溶体,Cu中间层有效地阻隔了Ti与不锈钢之间的扩散和反应。在连接时间为120 s时得到了最大的连接强度346 MPa。在拉伸载荷下,接头沿Ti/Cu界面发生脆性断裂。脉冲加压扩散连接能在一定程度上降低界面金属间化合物对接头性能的有害作用,提高接头强度,但不能完全消除界面金属间化合物对接头的不利影响。     

铜作中间层钛与不锈钢的脉冲加压扩散连接（英文）

采用Cu作中间层对工业纯钛和1Cr18Ni9不锈钢进行了脉冲加压扩散连接。在连接温度850℃,脉冲压力8~20 MPa工艺条件下,在120~180 s时间内即实现了钛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。在Ti/Cu界面生成了大量的Ti-Cu金属间化合物;而在Cu/不锈钢界面只生成了Cu在奥氏体不锈钢中的固溶体,Cu中间层有效地阻隔了Ti与不锈钢之间的扩散和反应。在连接时间为120 s时得到了最大的连接强度346 MPa。在拉伸载荷下,接头沿Ti/Cu界面发生脆性断裂。脉冲加压扩散连接能在一定程度上降低界面金属间化合物对接头性能的有害作用,提高接头强度,但不能完全消除界面金属间化合物对接头的不利影响。     

Zr/Cu/Zr部分瞬间液相焊扩散连接Ti(C,N)-Al_2O_3陶瓷基复合材料

采用Zr箔/Cu箔/Zr箔中间层对Ti(C,N)-Al2O3陶瓷基复合材料进行部分瞬间液相扩散连接实验,研究保温时间对元素扩散及界面反应产物的影响,探讨了制约接头室温强度的因素,对比分析了在部分瞬间液相扩散连接过程中,辅助脉冲电流对元素扩散及接头强度的作用机制.结果表明,预置Zr箔/Cu箔/Zr箔中间层通过部分瞬间液相扩散连接,在加热温度950℃,保温时间15~30 min条件下接头强度达到最大值.保温时间过短,活性元素Zr削弱基体强度,保温时间过长,Zr与Cu在界面生成金属间化合物降低了接头的强度.扩散焊过程中施加辅助脉冲电流能够有效缓解接头的残余应力,防止裂纹在脆性基体材料中扩展;但是同时促进了界面处的反应进程,显著提高了界面处Cu-Zr金属间化合物的形成速度,使得界面易成为接头的薄弱环节.     

TiAl/V/Cu/40Cr钢扩散连接界面组织结构对接头强度的影响

扩散连接界面组织结构是影响连接性能的关键因素，不同的界面组织结构及生成相所决定的接合强度不同，研究了TiAl/V/Cu/40Cr钢的扩散连接，结果显示，在V/Cu及Cu/40Cr的连接界面处出现了对连接性能有利的无限固溶体层，而在TiAl/V界面处有金属间化合物层出现，接头全部断裂于TiAl/V界面处，TiAl/V界面生成的金属间化合物V5Al8脆性相严重弱化了接头性能，使接头强度仅为200MPa。     

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。     

氧化-生成物对钛合金/铜/不锈钢扩散连接界面组织及性能的影响

钛合金/钢异种金属结构扩散连接技术所涉及的核心问题之一就是了解氧化及生成的金属间化合物对接合界面组织和性能的影响及如何选择中间层金属。采用扫描电镜、X射线衍射等分析手段,考察了以铜为对象的表面氧化物和生成的金属间化合物对铜/钛合金及钛合金/铜/不锈钢扩散连接界面的组织和性能的影响。结果表明:铜表面的氧化程度对接合界面金属间化合物生成程度影响较大,在一定版芯的氧化极限内,表面氧化越强烈,生成的金属间化合物越多,不利于接头性能的提高;但金属间化合物对接合界面组织和性能的影响较氧化物CuO本身对接合界面性能的影响大,是影响接头强度的主要原因。直接作为钛合金的中间过渡层的铜箔不宜过厚。     

保温时间对钛-铜扩散连接接头界面组织的影响

在850℃、10 MPa压力下对纯钛和纯铜进行了扩散连接。采用扫描电镜对不同连接时间下接头界面微观组织进行了表征,以研究连接时间对连接界面组织的影响。实验结果表明,当连接时间为30 s时,在钛/铜界面上存在没有完全闭合的微观孔洞,无扩散反应层生成。当连接时间增加到60 s,在接头界面生成了βTi,Ti2Cu,Ti Cu和Ti3Cu4等金属间化合物相,反应层总厚度约2μm。当连接时间增加到90 s,在接头界面产生了βTi,Ti2Cu,Ti Cu,Ti3Cu4,Ti2Cu3和Cu4Ti等金属间化合物,反应层厚度增加约5μm。这说明随着连接时间的增加,由于钛/铜之间互扩散的加剧,反应层不断变厚。     

电场激活辅助AlMgB_(14)-TiB_2与金属的反应扩散连接及界面结构分析

采用FAPAS烧结工艺原位合成了Al Mg B14-Ti B2复合材料,并分别同步实现了与金属Nb和Mo的扩散连接。利用XRD、SEM和EDS等手段对连接界面扩散层的相组成、微观形貌和元素分布特征进行了分析;探讨了在电场、温度场、压力场多物理场耦合条件下的扩散层形成机制及扩散连接过程。结果表明,Al Mg B14-30%(质量分数)Ti B2复合材料与金属Nb和Mo可以实现同步合成和扩散连接,形成宽170~180μm的均匀致密的扩散连接层;Ti B2在烧结过程中富集于连接界面,并与金属反应生成金属间化合物;硼元素在浓度梯度作用下的连续扩散和金属间化合物的形成是扩散连接的主要机制。     

Microstructure,residual stresses and mechanical properties of diffusion bonded tungsten–steel joint using a V/Cu composite barrier interlayer

Diffusion bonding is a preferred method to join W and steel for divertor applications. To minimize the residual stress induced by the large mismatch of thermal expansion coefficients and to inhibit the formation of brittle intermetallic phases, a V/Cu composite barrier interlayer was designed and examined to produce a joint between W and steel. The diffusion bonding was carried out at 1050 °C for 1 h under a 10 MPa pressure in vacuum. Metallographic analysis revealed excellent bonding at all of the joining interfaces. Neither intermetallic compounds nor other brittle phases were found in the bonded region. Nano-indentation test across the joint interfaces demonstrated the effect of solid solution strengthening in the diffusion zone. The strength of the joint was as high as 402 MPa and the failure occurred predominantly at the W substrate near the W/V interface due to the residual stress concentration.     

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.     

复合阻隔法的阻隔效应原理及其在扩散连接中的应用

以TiAl金属间化合物增压涡轮与 4 0Cr钢轴的扩散连接为背景 ,提出了复合阻隔法扩散连接工艺 ,并探讨了阻隔效应原理 ,建立了从材料的扩散连接性角度出发的原子半径、原子电负性阻隔层选择原则。利用本文的扩散连接阻隔效应原理 ,确定了TiAl金属间化合物增压涡轮与 4 0Cr钢轴的扩散连接复合阻隔层为Ti/V/Cu ,由此得到的扩散连接接头在V/Cu及Cu/ 4 0Cr的连接界面处出现了对连接性能有利的无限固溶体层 ,在TiAl/Ti的接触面上生成了能够强化接头强度的Ti3 Al TiAl双相层和Ti的固溶体层 ,与TiAl/ 4 0Cr直接扩散连接相比 ,Ti/V/Cu复合阻隔层的加入 ,避免了在TiAl/4 0Cr的接触面上TiC、Ti3 Al、FeAl、FeAl2 金属间化合物脆性相的产生 ,接头强度高达4 2 0MPa ,因此利用本文的阻隔效应原理可以很好地进行复合阻隔层的选择     

键合界面金属间化合物对可靠性影响的研究现状

在微电子封装过程中,键合丝被广泛应用,而键合可靠性对于产品的应用性能有着极大的影响,受到人们的广泛关注。键合丝与常用的铝焊盘之间是异质材料,在应用和服役的过程中会在界面上产生金属间化合物(IMC),对器件可靠性产生影响,同时,键合强度也与键合丝和焊盘之间的界面反应联系密切,因此了解键合丝与铝焊盘之间金属间化合物的形成与演变对键合可靠性的影响是有必要的。本文综述了Au/Al、Ag/Al和Cu/Al三种键合界面上金属间化合物的形成与演变的研究现状,并根据目前的应用状况,展望了未来的应用发展前景。     

Microstructural Characteristics of Accumulative Roll-Bonded Ni-Al-Based Metal-Intermetallic Laminate Composite

The present investigation is an attempt to develop metal-intermetallic laminate composites based on Ni-Al system. In this study, Ni sheets and Al foils have been used for the development of Ni-Al laminate using accumulative roll-bonding technique at 773?K. The laminate composites were then subjected to the controlled annealing to affect reactive diffusion at the Ni/Al interface leading to intermetallic compound formation. The accumulative roll-bonded laminates showed good bonding of layers. Annealing treatment at 773?K led to formation of reaction product and maintained the interface integrity. A qualitative compositional analysis at the interfaces reflected the formation of Al-Ni compounds, and a gradual compositional gradient also across the interface. This process seems to be of promise so far as the continuous production of large scale metal-intermetallic laminate composites is concerned.     

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.     

Bonding Interface and Bending Deformation of Al/316LSS Clad Metal Prepared by Explosive Welding

The morphology, elemental distribution, and phase analysis of the bonding interface were investigated by means of SEM, EDS, and XRD to evaluate the interface bonding properties of Al/316LSS clad metal prepared by explosive welding method. Furthermore, the micro-hardness and bending properties were also investigated. The results indicated that the linear and wavy bonding interfaces coexisted and intermetallic phases were present in the local interfacial zone. Moreover, the micro-hardness value at the bonding interface with intermetallic phases was higher than that at the interface without any intermetallic phases. In addition, bulk metal compounds could easily lead to the generation of micro-cracks during the bending forming process.     

添加铜箔中间层的NiTi形状记忆合金超声波焊接

采用超声波焊接方法对添加铜箔中间层的NiTi形状记忆合金进行搭接焊,研究接头的表面形貌、界面形貌、相变行为、抗拉性能和断裂特点. 结果表明,超声波焊接能实现添加铜箔中间层的薄片状NiTi形状记忆合金的有效连接. NiTi焊缝表面存在明显压痕,界面处结合良好,无金属间化合物生成. NiTi形状记忆合金超声波焊缝呈可逆单相转变过程,接头强度达到母材的65%,断裂位置在母材区,断口形貌呈现韧性断裂特征. 超声波焊接方法将有效解决NiTi形状记忆合金采用传统熔焊方法时产生脆性金属间化合物的这一问题,为NiTi记忆合金的连接提供了新的解决途径.