Al共晶接触反应钎焊热力学分析

用扫描电镜和电子探针研究了Al共晶接触反应钎焊液的润湿行为,以分步法观察Cu在Al表面的润湿铺展过程,并运用热力学参数分析Al共晶接触反应钎焊机理,结果表明,Cu原子可以沿Al的晶界优先扩散,达到共晶成分后形成液相,实现Al 的共晶接触反应钎焊。     

锡在Cu6Sn5金属间化合物表面的润湿行为

利用改良座滴法研究了高真空条件下熔融纯Sn在350 ~ 450 ℃下分别与Cu₆Sn₅和T2纯铜的润湿行为. 结果表明,表面镀金的金属间化合物基板在各试验温度下的润湿性均优于纯铜基板;金属基板表面氧化膜对润湿性的影响不容忽视;离子溅射后表面形成的金膜可以作为一种改善润湿性及控制界面IMC厚度的有效方法;润湿性改善的机制为Sn与氧化膜的化学反应,界面析出IMC或者IMC的溶解过程并非限制铺展的主要因素;铺展过程表现出线性铺展规律,可用反应产物控制模型对其进行描述,计算得到Sn/Cu₆Sn₅和Sn/Cu两体系的铺展激活能分别为20.469 kJ/mol和22.270 kJ/mol.     

Wetting behavior of Zr55Cu30Al10Ni5 melt on alumina

The wetting behavior of molten Zr55 Cu30 Al10 Ni5 on Al2O3 was studied by the sessile drop method in high vacuum. The results show that wetting kinetic at 1 163 K is composed of three stages., incubation, quasi-steady decrease and trend constant. Precursor film forms surrounding the wetting tip when wetting temperature is above 1 163K. Formation of precursor film is related to the change of triple line configuration and results in good wettability.Chemical reaction dos not occur at the wetting interface. Al2O3 is an excellent reinforcement for Zr55 Cu30 Al10 Ni5 matrix composite in terms of wettability and reactivity. The kinetic relationship of spreading ratio with spreading timewas also investigated.     

EFFECTS OF Zn CONCENTRATION ON WETTABILITY OF Sn-Zn ALLOY ON Cu AND ON THE INTERFACIAL MICROSTRUCTURE BETWEEN Sn-Zn ALLOY AND Cu

The potential of using a hypoeutectic, instead of eutectic, Sn-Zn alloy as a lead-free solder has been discussed. The nonequilibrium melting behaviors of a series of Sn-Zn alloys were examined by differential thermal analysis. It was found that at a heating rate of 5℃/min, Sn-6.SZn exhibited no melting range. Dipping and spreading tests were carried out to characterize the wettability of Sn-Zn alloys on Cu. Both tests exhibited that Sn-6.5Zn has significantly better wettability on Cu than Sn-9Zn. The reaction layers formed during the spreading tests were examined. When the Zn concentration fell between 2.5wt%-9wt%, two reaction layers were formed at the interface, a thick and flat Cu5Zn8 adjacent to Cu and a thin and irregular Cu-Zn-Sn layer adjacent to the alloy. Only a Cu0Sn5 layer was formed when the Zn concentration decreased to 0.5wt%. The total thickness of the reaction layer（s） between the alloy and Cu was found to increase linearly with the Zn concentration.     

Sb含量对Sn-Bi系焊料性能的影响(英文)

研究Sb元素含量对Sn-Bi系焊料性能的影响。通过差示扫描量热法研究Sn-Bi-Sb焊料的熔化行为。采用铺展实验研究焊料在Cu基板上的润湿性。测试Sn-Bi-Sb/Cu结合界面的力学性能。结果表明:三元合金中含有包共晶反应形成的共晶组织,随着Sb含量的增加,共晶组织增多;在加热速率为5°C/min的条件下,三元合金显示出更高的熔点和更宽的熔程;添加少量Sb对Sb-Bi系焊料的铺展率有影响;在焊料铺展过程中形成反应过渡层,反应过渡层中存在Sb元素而无Bi元素,过渡层厚度随着Sb元素含量的增加而增大。Sn-Bi-Sb焊料的剪切强度随着Sb元素含量的增加而升高。     

Formation process of liquid in interface of Ti／Cu contact reaction couple

By using the Ti/Cu contact reaction couples, the dissolution behavior of Ti and Cu in the eutectic reaction process was investigated under different conditions. The results show that the formation of eutectic liquid phase has a directional property, i.e. the eutectic liquid phase forms first at the Cu side and then spreads along the depth direction of Cu. The width of the eutectic liquid zone when Ti is placed on Cu is wider than that when Ti is placed under Cu. The shape of the upside liquid zone is wave-like. This phenomenon indicates that the formation process and spreading behavior in the upside are different from those in the underside, and there exists void effect in the Cu side of underside liquid zone, this will result in the delaying phenomenon of the contact reaction between Ti and Cu,and distinctly different shapes of the both liquid zones. The formation process of Ti/Cu eutectic liquid zone is similar to that of the traditional solid-state diffusion layer, and the relationship between the width of liquid zone and holding time obeys a square root law.     

Effect of direct electric current on wetting behavior of molten Bi on Cu substrate

The effect of direct electric current on the wetting behavior of molten Bi on Cu substrate at 370°C was investigated by the sessile drop method. The wettability of molten Bi on Cu without an applied current is poor and the spreading time required to form the steady-state contact angle (about 102°) is approximately 30 min. With the increase of the applied electric current, the spreading of molten Bi on Cu is accelerated significantly and the steady-state contact angle decreases considerably. The cross-section SEM micrographs of the solidified Bi droplet on Cu substrate show that the electric current has a marked effect on the convection of melt. Correspondingly, the application of an electric current obviously enhances the dissolution of Cu into Bi melt, which may change the wetting triple line configuration. The improvement of wettability induced by electric current is also related to the additional driving force for wetting provided by the electromagnetic pressure gradient force.     

铝-铜搅拌摩擦焊搭接焊缝共晶组织形成与抑制

采用搅拌摩擦焊技术成功焊接了铝-铜异种金属搭接接头,研究了铝-铜FSW焊缝界面宏观形貌、组织行为特征及其与焊接热输入变化的相关性,揭示出铝-铜FSW焊缝界面行为演变的基本规律.结果表明,在相应的焊接工艺参数下,单位时间、单位焊缝长度的热输入越大,铝-铜界面越容易发生共晶反应,生成Al-CuAl₂共晶体组织,直接影响焊接宏观接头抗剪力学性能,而随着热输入的减小,共晶反应程度及范围减小;也就是说,热输入的减少可明显抑制共晶反应的发生.     

半导体激光加热时间对焊膏在铜基板上润湿铺展性能的影响

采用半导体激光软钎焊系统对Sn63Pb37和Sn96Ag3.5Cu0.5焊膏在铜基板上的润湿铺展性能进行了试验,研究了不同激光加热时间对钎料润湿铺展性能的影响,采用扫描电镜分析了Sn63Pb37和Sn96Ag3.5Cu0.5钎缝的显微组织和钎缝界面区组织特征.结果表明,在一定的激光输出功率下,随着激光加热时间的增加,两种钎料的润湿性都得到提高.其中Sn-Pb钎料焊膏的加热时间达到1.5 s时,润湿面积和润湿角趋于稳定,而Sn-Ag-Cu钎料焊膏润湿性需要达到2.5 s时润湿面积和润湿角才趋于稳定.     

In对Sn-8Zn-3Bi无铅钎料润湿性的影响

首先采用铺展法测试了Sn-8Zn-3Bi-(0～5)In钎料合金的铺展性.结果表明,少量In的加入提高了钎料的润湿性.当In含量达到0.5%时(质量分数,下同),钎料在铜基底上的铺展面积最大.采用气泡最大压力法对Sn-8Zn-3Bi-(0～1.5)In钎料熔体进行了表面张力测试.加入0.5%的In大大降低了Sn-8Zn-3Bi钎料熔体的表面张力,但进一步增加In的含量导致熔体表面张力增大.最后采用润湿平衡法对上述钎料进行了润湿力测试.结果表明0.5%In的加入使合金的润湿力达到最大,其原因是钎料/铜界面的界面张力减小.     

Wetting kinetics of SiC nanoparticle reinforced Sn-Pb eutectic solders

SiC nanoparticles reinforced eutectic Sn-Pb solder were prepared by mechanical mixing method. Reactive wetting of the resultant composite solders on Cu substrates was investigated using real time, in-situ visualization of the triple-line movement. It was found that spreading rates of all solder pastes in this work do not obey Tanner's law of non-reactive spreading. SiC nano-particles slow down both the pre-melting and post-melting spreading rates of composite solder pastes. As the content of SiC nano-particles increase, the melting point of composite solders decrease, and the spreading time of molten composite solder pastes increases.     

Atomic morphology and chemical reactions of the reactive wetting front

Morphology at the reactive wetting front during spreading was first observed in situ at an atomic scale using a high resolution transmission electron microscope. Two typical nanomorphologies of an Ag–Cu–Ti molten alloy were observed on a SiC substrate depending on the nucleation position of the reaction product, TiC. In the case of the precursor atomic thin layer spreading ahead of the droplet of the molten alloy, the TiC nucleated in the thick region of the precursor, which was a few nm behind the tip of the precursor layer. In contrast, molten alloy spreading with TiC growing simultaneously at the tip was also observed. In this case, the precursor layer on SiC did not exist. Nucleation and growth rate of the reaction product were related to the tip morphology.     

Microstructure and Property of Cu/Al Joint Brazed with Al-Si-Ge Filler MetalEI北大核心CSCD

Cu/Al brazing has good prospect for applications in the air conditioning and refrigeration industry. A suitable filler metal is the key of Cu/Al brazing. The chemical and physical properties of the filler metal have great influence on the brazing process and parameters. And the strength of the brazing joint is closely related to the properties of the filler metal and the brazing process. While the previous studies have not developed a kind of Cu/Al brazing filler metal which can achieve a tough joint at a low brazing temperature. In this work, the Al-5.6Si-25.2Ge filler metal was first used to braze Cu/Al dissimilar metals, and the melting characteristics of the filler metal, spreading wettability, Cu interfacial structure and strength of brazed joint were investigated systematically. Additionally, the common Zn-22Al filler metal was also used for comparison. The results show that the Al-5.6Si-25.2Ge filler metal possesses low melting temperature (about 541 degrees C) and excellent spreading wettability on Cu and Al base metals. The interfacial structure of Al-5.6Si-25.2Ge/Cu was CuAl2/CuAl/Cu3Al2. The thickness of planar CuAl and Cu3Al2 phases was only 1 similar to 2 mu m, and the thickness of cellular CuAl2 phase was about 3 mu m. The interfacial structure of Zn-22Al/Cu was CuAl2/CuAl/Cu9Al4, but the average thickness of the CuAl2 layer was up to 15 mm. The test results of the shearing strength show that the shearing strength of the Cu/Al joint brazed with Zn-22Al filler metal was only 42.7 MPa, but the shearing strength brazed with Al-5.6Si-25.2Ge filler metal was higher (53.4 MPa).     

相图计算在电子材料焊接中的应用

焊料与基体的界面反应对高性能电子材料焊接接头的力学性能和可靠性都有着很重要的影响。把焊接过程分为界面反应和剩余焊料凝固两个过程进行讨论，在相图热力学的基础上，通过计算亚稳相图、比较界面处局部平衡时各相形成驱动力大小，预测了Sn-3．5％Ag／Cu、Sn-25％Ag／Cu和Sn-3．5％Ag／Ni扩散偶界面反应过程中的中间相形成序列；同时利用Scheil—Gulliver凝固模型模拟了Sn-25％Ag／Cu体系中过剩焊料的非平衡凝固过程，预测了焊料在随后冷却过程中的相演变信息。计算预测的结果与前人的实验结果吻合很好。     

D-KH法制备AgCuSn合金钎料的性能研究

分别采用熔铸法和D-KH法(叠轧复合-扩散合金化工艺)制备了Ag-22.4Cu-20Sn钎料合金,采用XRD、SEM、DSC及万能力学试验机等测试技术,对合金相组成、显微组织、熔化特性、钎焊接头的剪切强度和钎焊界面形貌等进行了对比研究。结果表明,D-KH法制备的钎料相组成为(Ag)、Cu3Sn、Ag5Sn相,而熔铸法制备的钎料相组成为(Ag)、Cu3Sn、Ag5Sn以及Cu41Sn11相;D-KH法制备的钎料合金液固相线均降低,熔程减小。与熔铸法相比,用D-KH法制备得到的厚度0.1 mm的钎料薄带,润湿铺展性更优、接头剪切强度更高、接头强度稳定性更好。     

Y2Cu2O5光催化剂的制备及模拟太阳光催化产氢

分别用固相法和液相法制备Y2Cu2O5光催化剂,利用热重差热分析(TG-DTA)、X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外可见光漫反射光谱(UV-Vis DRS)等技术对光催化剂进行表征。在模拟太阳光照射条件下,以草酸(H2C2O4)为牺牲剂对所制得的光催化剂制氢性能进行评价,考察制备方法和牺牲剂类型等因素对其产氢性能的影响以及光催化剂的稳定性能。结果表明:溶胶凝胶法所得样品中含有Y2O3杂质,为Y2Cu2O5与Y2O3的混合物;固相法所得样品为纯净的Y2Cu2O5,具备较高的光催化产氢活性。用固相法制备的光催化剂Y2Cu2O5,当其用量为0.8 g/L、草酸为牺牲剂且初始浓度为0.05 mol/L时,表现出最佳光催化产氢活性,其产氢量为3.78mmol/(h.g)。但Y2Cu2O5在草酸溶液中不稳定,会与草酸反应生成Y2(C2O4)3.2H2O,导致产氢活性降低。     

合金元素对6063铝合金阶梯焊中温钎料性能的影响

运用正交试验法,通过改变Si,Cu,Ni元素以及混合稀土RE元素的配比,研究含量的变化对Al-Si-Cu-Ni-RE钎料的熔点、铺展性以及抗剪强度的影响,并通过扫描电镜及能谱分析了钎料内部显微组织;通过研究发现,钎料的成分及加热温度是影响铺展面积的主要因素;对钎料显微组织分析可知,钎料中黑色的脆性θ(CuAl2)相和区域偏析的絮状相不利于接头的性能,而具有面心立方固溶体的基体相α(Al)以及球状聚集的Si相,使得钎料的力学性能优良.结果表明,对钎料熔点的影响方面,Cu元素的影响最大,其次为Ni,Si,RE元素,钎料的熔点随着Cu元素含量的增加而急剧下降.     

Cu/Mo双涂层改性SiCf/Ti6Al4V复合材料的界面与性能

采用箔-纤维-箔(FFF)法分别制备无涂层、C涂层和Cu/Mo双涂层改性的SiCf/Ti6Al4V复合材料,对制备态复合材料的力学性能和界面微观组织进行对比分析,进一步研究不同真空热暴露处理对Cu/Mo双涂层改性复合材料的界面微区的影响规律。结果表明,制备态下Cu/Mo涂层比C涂层较好地改善了复合材料的界面组织和性能,且对基体和纤维中元素扩散均具有一定的阻挡作用;求得900℃下SiCf/Cu/Mo/Ti6Al4V界面反应的生长动力学公式为H=1.380t1/2+5.397。     

SiO2-BN复相陶瓷润湿性及其接头微观组织

采用座滴法开展Ag-21Cu-4.5Ti合金钎料对SiO₂-BN复相陶瓷润湿与铺展行为研究. 利用SEM、XRD分析润湿界面微观组织以及形成机理. 通过调控SiO₂-BN复相陶瓷中BN含量,研究Ag-21Cu-4.5Ti/SiO₂-BN复相陶瓷润湿体系的润湿模型. 结果表明,Ag-21Cu-4.5Ti/SiO₂-BN复相陶瓷润湿体系的典型界面反应产物为TiN和TiB₂,随着体系BN含量的增加,润湿性逐渐变好. 对SiO₂-BN复相陶瓷与Nb进行钎焊试验,典型界面组织为SiO₂-BN复相陶瓷/TiN + TiB₂/Ti₂Cu + (Ag,Cu)/(βTi,Nb)/Nb. 接头抗剪强度随着钎焊时间升高先增大后减小,当钎焊温度为880 ℃,保温时间10 min时,钎焊接头抗剪强度最高,到达39 MPa.