Acta Metallurgica Sinica, 2017, 53(6): 719-725
doi: 10.11900/0412.1961.2016.00342
Al-Si-Ge钎料钎焊Cu/Al接头组织与性能研究

Microstructure and Property of Cu/Al Joint Brazed with Al-Si-Ge Filler Metal
牛志伟, 叶政, 刘凯凯, 黄继华, 陈树海, 赵兴科

摘要:

首次采用Al-5.6Si-25.2Ge钎料对Cu/Al异种金属进行了炉中钎焊,分别从钎料的熔化特性、铺展润湿性、Cu侧界面组织以及钎焊接头强度等方面进行了系统研究,并与Zn-22Al钎料钎焊结果进行对比。结果表明,Al-5.6Si-25.2Ge钎料具有较低的熔化温度(约541 ℃),同时在Cu、Al母材上均具有良好的铺展润湿性。Al-5.6Si-25.2Ge/Cu界面由CuAl2/CuAl/Cu3Al2三层化合物组成,其中CuAl和Cu3Al2呈层状,厚度较薄,仅为1~2 μm;CuAl2呈胞状,平均厚度约为3 μm。Zn-22Al/Cu界面结构为CuAl2/CuAl/Cu9Al4,其中CuAl2层平均厚度高达15 μm。接头抗剪切强度测试结果表明,Zn-22Al钎料钎焊Cu/Al接头抗剪切强度仅为42.7 MPa,而Al-5.6Si-25.2Ge钎料钎焊Cu/Al接头具有更高的抗剪切强度,为53.4 MPa。

关键词: Al-Si-Ge钎料 ; Cu/Al接头 ; 界面组织 ; 抗剪强度

Abstract:

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 ℃) 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 1~2 μm, and the thickness of cellular CuAl2 phase was about 3 μm. The interfacial structure of Zn-22Al/Cu was CuAl2/CuAl/Cu9Al4, but the average thickness of the CuAl2 layer was up to 15 μm. 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).

Key words: Al-Si-Ge filler metal ; Cu/Al joint ; interfacial structure ; shearing strength

“Al代Cu”是目前工业生产中为降低成本而提出的,其技术关键是解决Cu/Al异种金属的连接问题[1~3]。目前,最理想的方法是钎焊连接[4,5],采用钎焊技术可以获得强度较高和气密性良好的接头。常用于Cu/Al异种金属钎焊的钎料主要有Sn-Zn系[6~8]、Zn-A1系[9~11]和Al-Si系[12,13]。Sn-Zn系钎料钎焊Cu/Al接头的强度较低,抗腐蚀性能较差。Zn-Al系钎料,因其钎焊Cu/Al接头的强度较高,是目前Cu/Al钎焊常用的钎料,尤其是Zn-15Al和Zn-22Al钎料[14]。但由于Zn-Al钎料与Cu、Al母材的电极电位相差较大,因此钎焊接头极易引起电化学腐蚀[15]

Al-Si钎料主要为Al-Si共晶成分点附近的钎料。左柯等[16]和郑建峰等[17]对适用于Cu/Al钎焊的Al-Si和Zn-Al钎料的抗腐蚀性能进行了对比研究。结果表明,相对于Zn-Al钎料,Al-Si钎料具有更加优异的抗腐蚀性能。此外,Al-Si钎料具有优异的钎焊工艺性能[18]。然而,由于Al-Si钎料熔点较高,钎焊Cu/Al时极易引起Al母材一侧的过烧软化[19];同时,采用Al-Si钎料需要更高的钎焊温度,Cu侧界面易发生剧烈的界面反应,生成大量的脆性金属间化合物,导致钎焊接头强度极低,接头抗剪切强度不超过20 MPa[13,20]

Al-Si-Ge钎料较之传统Al-Si钎料具有较低的熔点和更优的铺展润湿性,在Al及铝合金钎焊中得到广泛应用[21,22]。本工作将Al-5.6Si-25.2Ge钎料作为研究对象[15,23],首次尝试用于钎焊Cu/Al异种金属,对钎焊接头中Cu侧界面组织及接头性能进行分析,并与Zn-22Al钎料进行对比研究。

1 实验方法

实验所用钎料成分为Al-5.6Si-25.2Ge、Zn-22Al和Al-12Si (质量分数,%)。其中Zn-22Al为常用的商业钎料,作为钎焊接头组织和性能研究的对比钎料;Al-12Si为共晶钎料,因其钎焊Cu/Al接头强度极低[10,17],仅作为钎料熔点研究的对比钎料。所有钎料均采用纯度99.999%的Ge、99.999%的Zn、99.99%的Si和99.6%的Al为原材料,在井式坩埚炉中进行熔炼,为了防止钎料合金在熔炼过程中被氧化,采用NaCl∶KCl=1∶1 (质量比)熔盐进行覆盖保护。熔化后进行充分搅拌,以尽量减少元素在金属液中的比重偏析。

图1 接头装配示意图

Fig.1 Schematic of the brazed specimen (unit: mm)

2种钎料在Cu、Al母材上的铺展润湿性测试在Ar气保护钎焊炉中进行,钎料的质量为0.15 g,所用钎剂为自行研制的AlF3-KF-KCl-CsF无腐蚀钎剂,熔化区间为415~488 ℃。钎焊接头采用搭接的形式,母材采用尺寸为60 mm×20 mm×3 mm的1060纯Al板和60 mm×20 mm×2 mm的TP2脱氧纯Cu板,搭接长度为2 mm,搭接间隙控制在(0.3±0.05) mm,钎料的质量为0.2 g,钎焊接头装配示意图如图1所示。在实际应用中,钎焊温度高于钎料熔点25~60 ℃时,钎焊工艺性能最佳[24],所以本实验采用的铺展和钎焊实验温度均为高于钎料液相线温度30 ℃。

采用CR-G型高温差热分析仪(DTA)测定钎料合金的熔化温度,加热速率为15 ℃/min。采用XTZ-AT体视显微镜对铺展实验试样进行拍照,并利用ImageTool3.0软件对铺展面积进行测量。采用Quanta 250型扫描电子显微镜(SEM)和其附带的能谱仪(EDS)对 Cu/Al 接头界面结构和断口形貌以及Cu/Al 接头界面化合物成分进行分析。采用MiniFlex 600 X射线衍射仪(XRD,CuKα)对钎料合金的相组成进行分析。实验过程中,炉膛升温速率40 ℃/min,钎焊保温时间40 s,钎焊接头取出后空冷至室温。Cu/Al钎焊接头的抗剪切强度按照GB/T11363-2008,采用MTS810型万能材料试验机进行测试,为保证结果的准确性,每种钎料成分钎焊3组试样,取平均值作为最终结果。

2 实验结果与讨论
2.1 钎料显微组织

Al-5.6Si-25.2Ge和Zn-22Al钎料显微组织和相组成如图2所示。结合EDS分析可知,Al-5.6Si-25.2Ge钎料中,长条状灰色相为Ge在Si中的固溶体;块状亮白色相为Si在Ge中的固溶体;黑色基体为α-Al相,均匀分散于整个钎料区。为进一步确定Al-Si-Ge钎料合金的相组成,对钎料合金进行了XRD分析。图2b为Al-5.6Si-25.2Ge钎料合金的XRD谱,证实了Al-Si-Ge钎料合金是由α-Al相、Si固溶体相和Ge固溶体相组成。

图2c和d所示,Zn-22Al钎料的基体组织主要为α-Al相、β-ZnAl相和η-Zn相,其中粗大的树枝晶为β-ZnAl相,树枝晶内部为η-Zn相,间隙中的黑色相为α-Al相。β-ZnAl相是铝基固溶体或以ZnAl为基的有序固溶体,通常情况下,β-ZnAl相只在中温区(443~275 ℃)存在,降温通过共析温度时将发生共析转变:β-ZnAl→α-Al+η-Zn,由于钎料合金在熔炼过程中凝固速率较快,导致β-ZnAl相没有来得及完全转变为η-Zn相,从而钎料组织中有β-ZnAl相的存在[24]

图2 Al-5.6Si-25.2Ge和Zn-22Al钎料的SEM像及XRD谱

Fig.2 SEM images (a, c) and XRD spectra (b, d) of Al-5.6Si-25.2Ge (a, b) and Zn-22Al (c, d) filler metals

2.2 钎料的熔化特性

图3所示为Al-12Si、Al-5.6Si-25.2Ge和Zn-22Al钎料合金的DTA曲线。从图中可以看出,Al-12Si钎料合金的液相线温度最高,为585 ℃;Al-5.6Si-25.2Ge钎料的液相线温度比Al-12Si钎料下降了44 ℃,可以在更低的温度下实现Cu/Al钎焊,防止母材过烧软化;Zn-22Al钎料的液相线温度最低,为490 ℃。结合Al-5.6Si-25.2Ge和Zn-22Al钎料的液相线温度,设定Al-5.6Si-25.2Ge和Zn-22Al钎料的钎焊温度分别为571和520 ℃。

图3 钎料的DTA曲线

Fig.3 DTA curves of filler metals

2.3 钎料的铺展润湿性

在钎焊过程中,钎料在Cu、Al母材上的铺展面积反应了钎料润湿填缝的能力。经测量,Al-5.6Si-25.2Ge和Zn-22Al钎料在Al母材上的平均铺展面积分别为566.2和478.5 mm2,由于Zn在Al中具有极大的固溶度,导致Zn向Al母材中产生严重的晶间渗透,减弱了Zn-Al钎料在Al母材上的铺展。相对于在Al母材上的铺展,Al-5.6Si-25.2Ge和Zn-22Al钎料在Cu上的铺展面积均较小,分别为119.6和69.8 mm2,但Al-5.6Si-25.2Ge钎料的铺展面积更大,约为Zn-22Al钎料的2倍。因此,相对于Zn-22Al钎料而言,Al-5.6Si-25.2Ge钎料在Cu、Al母材上均具有较好的铺展润湿性,更有利于实现Cu/Al异种金属的钎焊连接。

2.4 Cu/Al接头中Cu侧界面组织结构

Al-5.6Si-25.2Ge和Zn-22Al钎料钎焊Cu/Al接头Cu侧界面显微组织如图4所示。表1为图4中典型相的EDS分析结果。如图4a所示,Al-Si-Ge钎料与Cu母材发生了明显的界面反应,可明显观察到3层界面结构:I层、II层、III层。I层厚度较大,呈胞状或树枝状,根据成分分析可判断为CuAl2相;II层厚度较小,为1 μm左右,呈层状、分布均匀连续,根据EDS分析可判断为CuAl相;III层最靠近Cu母材侧,界面层厚度为2 μm左右,EDS分析表明为Cu3Al2相。对Al-Si-Ge钎料/Cu界面区进行元素线扫描分析(图4b),观察到三层化合物中Cu、Al元素的分布规律,证实了Al-Si-Ge钎料/Cu界面处由CuAl2/CuAl/Cu3Al2三层化合物组成。Al-Si-Ge钎料中的Ge元素没有参与界面反应,靠近界面处在CuAl2相(A)之间分布着灰白色的相(D),EDS分析结果表明灰白色的相是Ge的固溶体相。

图4 Al-5.6Si-25.2Ge和Zn-22Al钎料钎焊Cu/Al接头的SEM像和EDS元素线扫描结果

Fig.4 SEM images (a, c) and EDS element line scanning along the lines in Figs.4a and c (b, d) of Cu/Al joints brazed with Al-5.6Si-25.2Ge (a, b) and Zn-22Al (c, d) filler metals

图4c所示为Zn-Al钎料钎焊Cu/Al接头Cu侧界面组织结构。可以看出Cu侧界面同样包含3个化合物层。结合表1中EDS分析结果以及图4d中的元素分布规律,可以得出Zn-Al钎料/Cu界面处由CuAl2/CuAl/Cu9Al4三层化合物组成,其中CuAl2层厚度较大,平均厚度约为15 μm。

表1 图4中Cu/Al接头界面区物相的EDS分析结果
Table 1 EDS results of phases in the interfacial zones of the Cu/Al joints in Fig.4
Position
in Fig.4
Atomic fraction / % Phase
Al Cu Ge Si
A 67.15 32.85 - - CuAl2
B 48.22 51.78 - - CuAl
C 41.41 58.59 - - Cu3Al2
D - - 78.54 21.46 Ge solid solution
E 69.09 30.91 - - CuAl2
F 51.17 48.83 - - CuAl
G 29.43 70.57 - - Cu9Al4

表1 图4中Cu/Al接头界面区物相的EDS分析结果

Table 1 EDS results of phases in the interfacial zones of the Cu/Al joints in Fig.4

Cu/Al钎焊接头中Cu侧界面是最薄弱的区域,因为Cu侧界面极易形成复杂的化合物层,严重制约着Cu/Al钎焊接头的力学性能。当采用Al-5.6Si-25.2Ge钎料钎焊Cu和Al时,Cu侧界面生成CuAl2/CuAl/Cu3Al2化合物层,CuAl和Cu3Al2化合物靠近Cu母材侧,厚度极薄。CuAl2化合物硬度高而塑性低,抵抗裂纹扩展能力低,对Cu/Al钎焊接头强度起决定性作用。对比图4a和c可以看出,采用Al-5.6Si-25.2Ge钎料钎焊Cu/Al接头,CuAl2层呈胞状生长在Cu侧界面上,CuAl2相之间分布着Ge固溶体相, Ge固溶体相的存在阻碍了CuAl2相的大片状生长。而采用Zn-22Al钎焊Cu/Al接头,Cu侧界面CuAl2层呈大片状分布在Cu侧界面处,厚度远大于采用Al-5.6Si-25.2Ge钎料钎焊接头。采用Zn-22Al钎料时,钎焊温度较采用Al-5.6Si-25.2Ge钎料时更低,一般情况下,在较低温度下原子的扩散速率会更低,界面反应以及界面化合物的生长速率也相应较低。但是实验结果显示Zn-22Al钎料与Cu母材侧的界面反应反而更为容易,界面化合物生长更为迅速。仔细分析接头界面处的化合物层可以发现,当采用2种不同的钎料时,Cu/Al钎焊接头界面处的化合物种类发生了变化。在最靠近Cu母材一侧的位置,当采用Al-5.6Si-25.2Ge钎料时,生成的金属间化合物为Cu3Al2,该化合物为六方结构,晶格常数a=0.4146 nm,c=0.5063 nm;而当采用Zn-22Al钎料时,生成的金属间化合物为Cu9Al4,该化合物为简单立方结构,晶格常数a=0.8702 nm。Cu原子半径为0.1278 nm,Al原子半径为0.1820 nm。根据2种化合物的晶格类型以及晶格常数可以推断,Cu3Al2的致密度较Cu9Al4高。在钎焊过程中,当靠近Cu一侧生成的金属间化合物为Cu3Al2时,Cu原子继续向钎缝内部方向扩散的阻力大大增加,因此导致靠近钎料金属一侧的化合物生长受到抑制。具体体现为在利用Al-5.6Si-25.2Ge钎料钎焊Cu/Al时,即使钎焊温度高于Zn-22Al钎料钎焊温度,但是界面化合物层厚度,特别是靠近钎缝侧的CuAl2化合物厚度明显小于利用Zn-22Al钎料钎焊的接头。

2.5 Cu/Al接头抗剪切强度及断口分析

采用Al-5.6Si-25.2Ge和Zn-22Al钎料钎焊Cu/Al接头,Cu侧界面结构在化合物种类和形态上存在较大的差异,这种差异势必对Cu/Al接头的力学性能产生显著的影响。2种钎料钎焊Cu/Al接头所获得的抗剪切强度差别较大,Zn-22Al钎料钎焊Cu/Al接头抗剪切强度为42.7 MPa,与文献[25]研究结果基本一致;Al-5.6Si-25.2Ge钎料钎焊Cu/Al接头抗剪切强度较大,达到53.4 MPa。

接头界面结构对接头强度的影响直接反映在接头的断口形貌上。图5分别为2种钎料钎焊Cu/Al接头Cu母材一侧的断口形貌。钎焊接头均断裂于Cu母材/钎缝界面处,结合断裂试样界面的典型SEM像(图6)分析可知,断裂位置位于CuAl2化合物的根部。裂纹萌生于CuAl2化合物的根部,并在该化合物内部扩展,不管是用哪一种钎料钎焊的Cu/Al接头,其断裂位置完全处于CuAl2化合物的内部。接头的断裂与CuAl2化合物有非常大的关系,大厚度的CuAl2化合物片层对结构变形的耐受力非常低,是导致接头断裂失效的直接原因。Cu/Al-5.6Si-25.2Ge/Al接头断口形貌如图5a所示,断口分布着大量的撕裂棱及较浅的韧窝,钎焊接头表现出明显的韧性断裂特点;此外,断口表面也可观察到脆性断裂所产生的解理面,Al-5.6Si-25.2Ge/Cu母材界面化合物层厚度较小,且带有胞状突起,裂纹扩展所需能量较大,是接头出现大量撕裂棱的主要原因,Cu/Al-5.6Si-25.2Ge/Al钎焊接头也因此具有较高的抗剪切强度,为53.4 MPa。图5b所示为Cu/Zn-22Al/Al接头断口形貌。可以看出断口表面仅有少量撕裂棱,大部分区域为具有脆性断裂特征的解理面,这与钎焊接头中Cu侧界面存在厚度较大的CuAl2层有关,钎焊接头抗剪切强度也因此较低,为42.7 MPa。

图5 Al-5.6Si-25.2Ge和Zn-22Al钎料钎焊Cu/Al接头断口的SEM像

Fig.5 SEM images of the fracture surface of the Cu/Al joints brazed with Al-5.6Si-25.2Ge (a) and Zn-22Al (b) filler metals

图6 典型的Cu/Al钎焊接头断裂位置的SEM像

Fig.6 Typical SEM image of the fracture position of the Cu/Al joint

3 结论

(1) 采用Al-5.6Si-25.2Ge钎料钎焊Cu/Al异种金属,由于钎料具有较低的熔点和优异的铺展润湿性,成功实现了Cu/Al钎焊接头的连接。

(2) Al-5.6Si-25.2Ge/Cu界面处由CuAl2/CuAl/Cu3Al2三层化合物组成,其中CuAl和Cu3Al2呈层状,厚度较薄,为1~2 μm;CuAl2呈胞状,平均厚度约为3 μm,钎焊接头抗剪切强度较高,为53.4 MPa。Zn-22Al/Cu界面结构为CuAl2/CuAl/Cu9Al4,其中CuAl2层平均厚度高达15 μm,钎焊接头抗剪切强度仅为42.7 MPa。

(3) Cu/Al钎焊接头中Cu侧界面结构是影响钎焊接头强度的关键,Al-5.6Si-25.2Ge/Cu界面处CuAl2层呈突起状钉扎于钎料层中,且厚度较薄,是Cu/Al-5.6Si-25.2Ge/Al钎焊接头抗剪切强度比Cu/Zn-22Al/Al高的原因。

The authors have declared that no competing interests exist.

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[1] Ning F Z.Low temperature friction welding of aluminum to copper[J]. Acta Metall. Sin., 1978, 14: 179
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(宁斐章. 铝-铜低温摩擦焊[J]. 金属学报, 1978, 14: 179)
[2] Zhang H T, Liu D, Feng J C, et al.Reactive contact brazing between Aluminium alloy and copper by high frequency induction metho[J]. Trans. China Weld. Inst., 2012, 33(3): 89
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(张洪涛, 刘多, 冯吉才. 铝/铜高频感应接触反应钎焊[J]. 焊接学报, 2012, 33(3): 89)
对铝/铜异种金属接头的高频感应接触反应钎焊工艺进行了研究,在非真空条件下借助钎剂的去膜作用,实现了铝和铜的连接,并根据钎剂去膜过程和对接头力学性能的影响规律优化了钎剂组分.同时借助扫描电镜和能谱分析等分析手段,详细分析了接头的界面结构与物相组成.结果表明,试验中配制的钎剂65%ZnCl2+10%NaCl+25%NH4Cl钎焊效果较好,钎缝厚度约为80μm,钎缝主要由铝基固溶体和化合物Al2Cu弥散相组成,有大量的Zn元素和Na元素扩散进入钎缝,接头抗剪强度可以达到58 MPa.
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[3] Cong Q, Xu F M, Tan Y, et al.Influence of heat treatment on microstructure and mechanical properties of Al/Al-Cu graded materials[J]. Acta Metall. Sin.(Engl. Lett.), 2011, 24: 118
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[4] Easton D, Zhang Y X, Wood J, et al. Brazing development and interfacial metallurgy study of tungsten and copper joints with eutectic gold copper brazing alloy [J]. Fusion Eng. Des., 2015, 98-99: 1956
Current proposals for the divertor component of a thermonuclear fusion reactor include tungsten and copper as potentially suitable materials. This paper presents the procedures developed for the successful brazing of tungsten to oxygen free high conductivity (OFHC) copper using a fusion appropriate gold based brazing alloy, Orobraze 890 (Au80Cu20). The objectives were to develop preparation techniques and brazing procedures in order to produce a repeatable, defect free butt joint for tungsten to copper. Multiple brazing methods were utilised and brazing parameters altered to achieve the best joint possible. Successful and unsuccessful brazed specimens were sectioned and analysed using optical and scanning electron microscopy, EDX analysis and ultrasonic evaluation. It has been determined that brazing with Au80Cu20 has the potential to be a suitable joining method for a tungsten to copper joint.
DOI:10.1016/j.fusengdes.2015.05.033      URL     [本文引用:1]
[5] Fu W, Song X G, Hu S P, et al.Brazing copper and alumina metallized with Ti-containing Sn0.3Ag0.7Cu metal powder[J]. Mater. Des., 2015, 87: 579
A Sn-based metallization layer was successfully prepared on the surface of alumina at 90002°C by using Ti-containing Sn0.3Ag0.7Cu (SAC, wt.%) metal powder. Reliable alumina/copper joints were obtained by brazing pre-metallized alumina and copper using SAC filler at 580–66002°C for 502min. The typical interfacial microstructure of brazed joint was copper/Cu 3 Sn layer/Cu 6 Sn 5 layer/β-Sn layer containing Ti 6 Sn 5 phase and Al 2 O 3 particles/alumina. As brazing temperature increased, the Cu–Sn intermetallic layers thickened rapidly and the amount of β-Sn phase reduced. When brazing temperature exceeded 64002°C, Kirkendall voids and microcracks formed at copper/Cu 3 Sn interface. The joints brazed at 580–62002°C possessed high shear strength and the highest average shear strength of 3202MPa was achieved when brazed at 62002°C. Fracture analyses indicated that the joints mainly fractured inside of the Cu 6 Sn 5 layer and β-Sn layer. The joints brazed above 62002°C demonstrated low shear strength due to the formation of Kirkendall voids which caused the joints fractured along the Cu/Cu 3 Sn interface.
DOI:10.1016/j.matdes.2015.08.081      URL     [本文引用:1]
[6] Xing F, Yao J, Liang J W, et al.Influence of intermetallic growth on the mechanical properties of Zn-Sn-Cu-Bi/Cu solder joints[J]. J. Alloys Compd., 2015, 649: 1053
The formation of intermetallic reaction layers and their influence on shear strength and fractography was investigated between the Zn–Sn–Cu–Bi (ZSCB) and Cu substrate during the liquid state reaction at 450°C after 10–90s. Results showed that reliable solder joints could be obtained at 450°C after 15–30s of wetting, accompanied by the creation of scallop ε-CuZn 5 , flat γ-Cu 5 Zn 8 and β-CuZn intermetallic layers in ZSCB/Cu interface. However, with excess increase of soldering time, a transient intermetallic ε-CuZn 4 phase was nuclear and grew at ε-CuZn 5 /γ-Cu 5 Zn 8 interface, which apparently deteriorated the shear strength of solder joints from 76.5MPa to 51.6MPa. The sensitivity of the fracture proportion was gradually transformed from monotonic ε-CuZn 5 to the mixture of ε-CuZn 4 and ε-CuZn 5 intermetallic cleavage. Furthermore, the growth mechanism of ε-CuZn 4 intermetallic phase at the ZSCB/Cu interface was discussed.
DOI:10.1016/j.jallcom.2015.07.231      URL     [本文引用:1]
[7] Zhou J, Sun Y S, Xue F.Microstructures and properties of Sn-Zn-Bi solder alloys[J]. Acta Metall. Sin., 2005, 41: 743
[本文引用:]
(周健, 孙扬善, 薛烽. 低熔点Sn-Zn-Bi无铅钎料的组织和性能[J]. 金属学报, 2005, 41: 743)
研究了Sn-Zn-Bi钎料的组织、相变及润湿性.在Sn-9Zn二元共晶的基础上加入质量分数为(2-10)%的Bi,合金结晶过程中形成富Zn的初生相这导致合金的结晶温度降低,也标志着熔点的降低,但熔程扩大.在加Bi基础上,适当降低Zn的含量则可以缩小熔程,且熔点无明显变化. Bi的加入明显改善了Si-Zn系钎料的润湿性,提高了钎料在Cu基底上的铺展面积,缩短了润湿时间.钎料中Zn原子向Cu基底的扩散而形成扩散反应层,导致钎料熔体/Cu界面能的下降.因此,钎料中Zn含量提高,其在Cu基底上的铺展面积增大,润湿力提高.而由于扩散过程需要一定时间,导致润湿时间延长.因此,必须合理控制Zn的含量以获得铺展性与润湿时间的良好匹配.
[8] Huang M L, Kang N, Zhou Q, et al.Effect of Ni content on mechanical properties and corrosion behavior of Al/Sn-9Zn-xNi/Cu Joints[J]. J. Mater. Sci. Technol., 2012, 28: 844
The effects of Ni content on the microstructure and the wetting behavior of Sn-9Zn-xNi solders on Al and Cu substrates, as well as the mechanical properties and electrochemical corrosion behavior of Al/Sn-9Zn-xNi/Cu solder joints, were investigated. The microstructure of Sn-9Zn-xNi revealed that tiny Zn and coarsened Ni 5 Zn 21 phases dispersed in the -Sn matrix. The wettability of Sn-9Zn-xNi solders on Al substrate was much better than that on Cu substrate. With increasing Ni content, the wettability on Cu substrate was slightly improved but became worse on Al substrate. In the Al/Sn-9Zn-xNi/Cu joints, an Al4.2Cu3.2Zn0.7 intermetallic compound (IMC) layer formed at the Sn-9Zn-xNi/Cu interfaces, while an Al-Zn-Sn solid solution layer formed at the Sn-9Zn-xNi/Al interface. The mixed compounds of Ni3Sn4 and Al3Ni dispersed in the solder matrix and coarsened with increasing Ni content, thus leading to a reduction in shear strength of the Al/Sn-9Zn-xNi/Cu joints. Al particles were segregated at both interfaces in the solder joints. The corrosion potentials of Sn-9Zn-xNi solders continuously increased with increasing Ni content. The Al/Sn-9Zn-0.25Ni/Cu joint was found to have the best electrochemical corrosion resistance in 5% NaCl solution.
DOI:10.1016/S1005-0302(12)60141-8      URL     [本文引用:1]
[9] Xiao Y, Ji H J, Li M Y, et al.Ultrasound-assisted brazing of Cu/Al dissimilar metals using a Zn-3Al filler metal[J]. Mater. Des., 2013, 52: 740
Ultrasound-assisted brazing of Cu/Al dissimilar metals was performed using a Zn–3Al filler metal. The effects of brazing temperature on the microstructure and mechanical properties of Cu/Al joints were investigated. Results showed that excellent metallurgic bonding could be obtained in the fluxless brazed Cu/Al joints with the assistance of ultrasonic vibration. In the joint brazed at 400°C, the filler metal layer showed a non-uniform microstructure and a thick CuZn 5 IMC layer was found on the Cu interface. Increasing the brazing temperature to 440°C, however, leaded to a refined and dispersed microstructure of the filler metal layer and to a thin Al 4.2 Cu 3.2 Zn 0.7 serrate structure in the Cu interfacial IMC layer. Further increasing the brazing temperature to 480°C resulted in the coarsening of the filler metal and the significantly growth of the Al 4.2 Cu 3.2 Zn 0.7 IMC layer into a dendrite structure. Nanoindentation tests showed that the hardness of the Al 4.2 Cu 3.2 Zn 0.7 and CuZn 5 phase was 11.4 and 4.65GPa, respectively. Tensile strength tests showed that all the Cu/Al joints were failed in the Cu interfacial regions. The joint brazed at 440°C exhibited the highest tensile strength of 78.93MPa.
DOI:10.1016/j.matdes.2013.06.016      URL     [本文引用:1]
[10] Ji F, Xue S B, Lou J Y, et al.Microstructure and properties of Cu/Al joints brazed with Zn-Al filler metals[J]. Trans. Nonferrous. Met. Soc. China, 2012, 22: 281
The mechanical properties and microstructural distribution of the Cu/Al brazing joints formed by torch-brazing with different Zn-Al filler metals were investigated.The microstructure of the Zn-Al alloys was studied by optical microscopy and scanning electron microscopy,and the phase constitution of the Cu/Al joints was analyzed by energy dispersion spectrometry.The results show that the spreading area of the Zn-Al filler metals on the Cu and Al substrates increases as the Al content increases.The mechanical results indicate that the shear strength reaches a peak value of 88 MPa when Al and Cu are brazed with Zn-15Al filler metal.Microhardness levels from HV122 to HV515 were produced in the three brazing seam regions corresponding to various microstructure features.The Zn-and Al-rich phases exist in the middle brazing seam regions.However,two interface layers,CuZn3 and Al2Cu are formed on the Cu side when the Al content in the filler metals is 2% and more than 15%,respectively.The relationship between intermetallic compounds on Cu side and Zn-xAl filler metals was investigated.
DOI:10.1016/S1003-6326(11)61172-2      URL     [本文引用:1]
[11] Ji F, Xue S B.Growth behaviors of intermetallic compound layers in Cu/Al joints brazed with Zn-22Al and Zn-22Al-0.05Ce filler metals[J]. Mater. Des., 2013, 51: 907
The structure development and growth rate of intermetallic compounds in Cu/Al brazed joint formed under aging treatment were investigated in this paper. Trace amount of rare earth Ce (0.0502wt.%) was added into Zn–22Al filler metal in order to reform the properties of the Cu/Al joint. The interfacial morphology and constituent phases at the interface were examined by the scanning electron microscopes (SEM) and X-ray energy dispersion spectrometry (EDS), respectively. The growth kinetics of intermetallic compounds formed in both systems (Zn–22Al and Zn–22Al–0.05Ce) was also investigated under different aging conditions. The results indicated that interface structure of Cu/Al brazed joints changed from CuAl 2 /CuZn 3 to CuAl 2 /CuAl/CuZn 3 and finally to ε/CuAl 2 /CuAl/CuZn 3 during aging. The growth rate of intermetallic compounds observed in the Zn–22Al system was higher than that in Zn–22Al–0.05Ce. Meanwhile, the activation energy of CuAl 2 phase increased from 76.902kJ/mol to 87.602kJ/mol with the 0.0502wt.% Ce addition. The results also revealed that the joint brazed with Zn–22Al–0.05Ce constantly possessed higher shear strength than that of Zn–22Al throughout the aging treatment. The addition of Ce into the Zn–22Al filler metal decreased the thickness of the intermetallic compound layer produced in the aging, resulting in higher fracture toughness.
DOI:10.1016/j.matdes.2013.04.069      URL     [本文引用:1]
[12] Yan F, Xu D R, Wu S C, et al.Microstructure and phase constitution near the interface of Cu/3003 torch brazing using Al-Si-La-Sr filler[J]. J. Mech. Sci. Technol., 2012, 26: 4089
Abstract IMC. Further experimental results also show that the rare earth element La in filler metal can not only refine the grain, but also promote the dispersion of intermetallic compounds into the brazing seam, which significantly improves the brazing seam microstructure and mechanical properties of the joints.
DOI:10.1007/s12206-012-0884-7      URL     [本文引用:1]
[13] Xia C Z, Li Y J, Puchkov U A, et al.Microstructure and phase constitution near the interface of Cu/Al vacuum brazing using Al-Si filler metal[J]. Vacuum, 2008, 82: 799
Brazing of Cu to Al using Al-Si filler metal has been carried out by vacuum brazing technology. The microstructure and the phase constitution in Cu/Al joint were studied by means of metallography, electron probe microanalyser (EPMA) and X-ray diffraction (XRD). Experimental results obtained showed that two kinds ofintermetallic compounds (IMCs) are formed near the interface of copper and brazing seam region and those are Cu
DOI:10.1016/j.vacuum.2007.11.007      URL     [本文引用:2]
[14] Yang H, Huang J H, Chen S H, et al.Influence of the composition of Zn-Al filler metal on the interfacial structure and property of Cu/Zn-Al/Al brazed joint[J]. Acta Metall. Sin., 2015, 51: 364
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(羊浩, 黄继华, 陈树海. Zn-Al钎料成分对Cu/Zn-Al/Al钎焊接头界面结构及性能的影响[J]. 金属学报, 2015, 51: 364)
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[15] Zhang Q Y, Zhuang H S.Brazing and Soldering Manual [M]. Beijing: China Machine Press, 2008: 55
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(张启运, 庄鸿寿. 钎焊手册 [M]. 北京: 机械工业出版社, 2008: 55)
[16] Zuo K, Zuo T J, Qiu G C, et al.Comparison of corrosion resistance between Al-Si brazing filler and Al-Zn brazing filler [A]. Proceedings of the Eleventh National Symposium on Refrigerators, Air Conditioners and Compressors[C]. Chuzhou: Chinese Association of Refrigeration, 2012: 293
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(左柯, 左铁军, 邱国才. Al-Si钎料和Al-Zn钎料抗腐蚀性能比较 [A]. 第十一届全国电冰箱(柜)、空调器及压缩机学术交流大会论文集[C]. 滁州: 中国制冷学会, 2012: 293)
[17] Zheng J F, Chen D J, Cai Q, et al.Comparison of corrosion resis tance between Al-Si brazing filler and Al-Zn brazing filler[J]. Household Appl. Technol., 2013, (10): 78
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(郑建峰, 陈德娟, 蔡蔷. Al-Si钎料和Al-Zn钎料耐蚀性能对比研究[J]. 家电科技, 2013, (10): 78)
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[18] Hosch T, Napolitano R E.The effect of the flake to fiber transition in silicon morphology on the tensile properties of Al-Si eutectic alloys[J]. Mater. Sci. Eng., 2010, A528: 226
The combined and separate effects of microstructural scale and silicon phase morphology on the mechanical properties of Al–Si eutectic alloys are investigated here. The Bridgman-type gradient-zone directional solidification method is employed to produce as-cast structures characteristic of the full range of practical (i.e. casting) growth velocities, and the corresponding mechanical properties are characterized by uniaxial tension testing. The results are analyzed in light of previously reported microstructural changes associated with the flake to fiber or “quench modification” transition [1] . Both tensile strength and elongation were found to increase with solidification rate. Application of the Nan–Clarke [2] micromechanical analysis to the Al–Si composite structure, incorporating the strengthening effects of reinforcement-induced dislocations, suggests that the decreasing microstructural scale alone is sufficient to account for the increase in tensile strength with solidification rate. However, the flake to fiber transition was found to have a particular relevance with regard to the fracture behavior of the alloy, increasing tensile elongation and decreasing the overall variability of tensile properties. A maximum in elongation was observed at approximately 600μm/s, corresponding to the upper threshold of the flake to fiber transition associated with complete disappearance of the flake morphology and dominance of the fibrous structure. These results emphasize the importance of understanding and controlling the flake to fiber transition that occurs with increasing solidification rate in Al–Si eutectic alloys.
DOI:10.1016/j.msea.2010.09.008      URL     [本文引用:1]
[19] Luo W, Wang L T, Wang Q M, et al.A new filler metal with low contents of Cu for high strength aluminum alloy brazed joints[J]. Mater. Des., 2014, 63: 263
The effect of Cu with low contents of 10, 12, 1502wt.% on the microstructure and melting point of Al–Si–Cu–Ni alloy has been investigated. Results showed that low-melting-point properties of Al–Si–Cu–Ni alloys with low contents of Cu were attributed to disappearance of Al–Si binary eutectic reaction and introduction of Al–Si–Cu–Ni quaternary reaction. With raising Cu content from 10 to 1502wt.%, the amount of complex eutectic phases formed during low temperature reactions (Al–Cu, Al–Si–Cu and Al–Si–Cu–Ni alloy reactions) increased and the melting temperature of Al–Si–Cu–Ni filler metals declined. Brazing of 6061 aluminum alloy with Al–10Si–15Cu–4Ni (all in wt.%) filler metal of a melting temperature range from 519.3 to 540.202°C has been carried out successfully at 57002°C. Sound joints can be obtained with Al–10Si–15Cu–4Ni filler metal when brazed at 57002°C for holding time of 6002min or more, and achieved high shear strength up to 144.402MPa.
DOI:10.1016/j.matdes.2014.06.033      URL     [本文引用:1]
[20] Liu H J, Shen J J.Progress in welding process of Al/Cu dissimilar metals[J]. Weld. Join., 2009, (3): 14
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(刘会杰, 沈俊军. 铝/铜异种材料的焊接研究[J]. 焊接, 2009, (3): 14)
由铝/铜异种材料组成的复合结构在电力工业具有广阔的应用前景,深入研究铝/铜的焊接方法及工艺是很有必要的.文中从熔焊、压焊、钎焊以及搅拌摩擦焊等几个方面,系统介绍了铝/铜异种材料焊接的研究进展.综合分析表明,熔焊方法不适于铝/铜的焊接,极易出现焊接裂纹和性能降低等问题;铝/铜的压焊应用较为广泛,每种具体的压焊方法各有其特点,应根据上件的结构尺寸加以选定.钎焊方法能成功实现铝/铜的焊接.但需要严格确定钎料成分和钎焊工艺.销/铜的搅拌摩擦焊研究刚刚开始,某些热点M题需要进一步深入研究.但发展前景非常广阔.
[21] Niu Z W, Huang J H, Chen S H, et al.Effects of germanium additions on microstructures and properties of Al-Si filler metals for brazing aluminum[J]. Trans. Nonferrous. Met. Soc. China, 2016, 26: 775
A series of Al-Si-Ge filler metals were studied for brazing aluminum. The microstructures and properties of the filler metals were investigated systematically. The results show that the liquidus temperature of Al-Si-Ge filler metals drops from 592 to 519 C as the content of Ge increases from 0 to 30% (mass fraction). As the content of Ge increases, bright eutectic Ge forms. However, as the Ge content exceeds 20%, the aggregation growth of the eutectic structure tends to happen and coarsened primary Si-Ge particle forms, which is detrimental to the properties of alloys. The Al-10.8Si-10Ge filler metal has good processability and wettability with the base metal Al. When this filler metal is used to braze 1060 aluminum, the complete joint can be achieved. Furthermore, the shear strength test results show that the fracture of brazed joint with Al-10.8Si-10Ge filler metal occurs in the base metal.
DOI:10.1016/S1003-6326(16)64167-5      URL     [本文引用:1]
[22] Schubert T H, Loser W, Teresiak A, et al.Preparation and phase transformations of melt-spun Al-Ge-Si brazing foils[J]. J. Mater. Sci., 1997, 32: 2181
A series of Al-Ge-Si alloys was melt spun into ribbons of about 40 μm thickness. The alloy compositions were selected so as to be suitable as filler metals with brazing temperatures <500°C. In the as-quenched state the foils were relatively brittle due to the occurrence of metastable phases. After appropriate annealing treatments between 300–400°C the metastable phases were transformed into a fine-grained microstructure of β-Ge(Si) particles within the α-Al matrix. This led to considerably improved mechanical properties, which are manifested in decreased microhardness levels near 100 HV 0.02 and bend radii <1 mm. The transformation process of foils on annealing was investigated by differential scanning calorimetry, transmission electron microscopy and X-ray diffraction methods. The intensity of X-ray reflections of the metastable and equilibrium phases as well as the lattice parameters of α-Al and β-Ge(Si) were evaluated as functions of the annealing temperature. Differences in the transformation behaviour of binary Al-Ge and ternary Al-Ge-Si alloys, in particular, the decreased transformation temperature for the decay of metastable phases in ternary alloys, were revealed.
DOI:10.1023/A:1018599527833      URL     [本文引用:1]
[23] Niu Z W, Huang J H, Yang H, et al.Preparation and properties of a novel Al-Si-Ge-Zn filler metal for brazing aluminum[J]. J. Mater. Eng. Perform., 2015, 24: 2327
The study is concerned with developing a filler metal with low melting temperature and good processability for brazing aluminum and its alloys. For this purpose, a novel Al-Si-Ge-Zn alloy was prepared according to Al-Si-Ge and Al-Si-Zn ternary phase diagrams. The melting characteristics, microstructures, wettability, and processing property of the alloy were investigated. The results showed that the melting temperature range of the novel filler metal was 505.2-545.1°C, and the temperature interval between the solidus and the liquidus was 39.9°C. Compared with a common Al-Si-Ge alloy, it had smaller and better dispersed β-GeSi solid solution precipitates, and the Zn-rich phases distributed on the boundary of the β-GeSi precipitates. The novel filler metal has good processability and good wettability with Al. There was one obvious transition layer with a thin α-Al solid solution between the filler metal and base metal, which is favorable to improve the strength of brazing joint.
DOI:10.1007/s11665-015-1509-y      URL     [本文引用:1]
[24] Yang L S, Wang H M, Chen Q D.High Aluminum Zn Alloys [M]. Xi'an: Northwestern Polytechnic University Press, 1997: 17
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(杨留栓, 王洪敏, 陈全德. 高铝锌合金 [M]. 西安: 西北工业大学出版社, 1997: 17)
[25] Zhang M, Xue S B, Dai W, et al.Effect of Ag on properties of Zn-Al brazing filler metal[J]. Trans. China Weld. Inst., 2010, 31(10): 73
[本文引用:]
(张满, 薛松柏, 戴玮. Ag元素对Zn-Al钎料性能的影响[J]. 焊接学报, 2010, 31(10): 73)
研究了Ag元素的添加量对Zn-Al钎料的熔化温度、铺展性能、 接头力学性能以及显微组织的影响.结果表明,随着Al元素含量的增加,钎料的熔化温度略有提高,在铝板及铜板上的铺展性能明显改善,钎焊接头力学性能显著 提高.当Ag元素的添加量达到3.3%(质量分数)时,钎焊接头力学性能最佳.继续增加Al元素含量,钎焊接头强度变化不大.在Zn-Al钎料中添加Ag 元素能够显著改善钎缝的显微组织,随着Al元素含量的增加,钎缝内部块状铜铝脆性相尺寸变小,产生应力集中的倾向减小,对应的接头强度提高.当Al元素含 量达到3.3%(质量分数)时,钎料的综合性能最佳.
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关键词(key words)
Al-Si-Ge钎料
Cu/Al接头
界面组织
抗剪强度

Al-Si-Ge filler metal
Cu/Al joint
interfacial structure
shearing strength

作者
牛志伟
叶政
刘凯凯
黄继华
陈树海
赵兴科

NIU Zhiwei
YE Zheng
LIU Kaikai
HUANG Jihua
CHEN Shuhai
ZHAO Xingke