Free Access
Issue
Metall. Res. Technol.
Volume 117, Number 3, 2020
Article Number 303
Number of page(s) 11
DOI https://doi.org/10.1051/metal/2020028
Published online 13 May 2020

© EDP Sciences, 2020

1 Introduction

The Al/Cu composite structures which take full advantage of both materials with the demands of low cost, light weight, conductivity, thermal conductivity and corrosion resistance have broadly been used in electric power, chemical, electrical, refrigeration and aerospace industries [1,2]. However, it is very difficult to obtain a reliable Al/Cu dissimilar joint because of the remarkable differences in physical and chemical properties between Al and Cu [3,4]. The intermetallic compounds (IMCs) are able to occur to form a brittle reaction layer, which deteriorate mechanical properties of the joints [5]. It is a challenge work for joining of Al to Cu by conventional fusion welding method. The key issue of welding Al/Cu dissimilar materials is thus considered to suppress the formation of the IMCs. The low thermal input processes have been made to join Al to Cu via reducing the heat input such as friction stir welding, ultrasonic welding, laser welding, electron beam welding and brazing [610]. Esmaeili et al. [11] reported the role of rotation speed on the IMCs formation and mechanical behavior of friction stir welded brass/aluminum 1050 couple. Balasundaram et al. [12] studied the effect of zinc interlayer on the Al/Cu joints using ultrasonic spot welding (USW). Yang et al. [13] investigated 6061 Al alloys to pure copper using resistance heat assisted ultrasonic welding. Although extensive studies have been done, it is insufficient to realize a good Al/Cu joint by fusion welding.

In recent years, cold metal transfer (CMT) process has been paid great attention to by researchers, which involves the reduced heat input and spatters during welding. In terms of lowering the heat input, decreasing the processing time and adding appropriate filler materials, it is expected to overcome the problems that occur during the fusion welding process [14,15]. CMT welding has advantages over conventional fusion welding in high flexibility, thinner IMC layer and low residual stress for joining dissimilar materials [16,17]. Consequently, the use of CMT heat source could improve the interfacial reaction and control the IMC growth in the interfacial regions. In order to obtain sound dissimilar joints, a novel fusion-brazing welding has also been developed [18,19]. The fusion-brazing method utilizes the concept originating from the difference in large melting point of the dissimilar metals to form a fusion welded joint on the side of the low melting point material and brazed joint on the side of the high melting point material. Accordingly, it is concluded that CMT welding-brazing is a potential technique for joining dissimilar materials. It thus seems to have a great prospect for Al/Cu welding. In comparison to lap joints, it is usually more difficult to achieve a sound dissimilar butt joint. The use of V-groove configuration during welding-brazing has been developed as a viable approach for dissimilar butt joints [20]. Unfortunately, limited studies have been concentrated on Al/Cu butt joints during CMT method. The microstructure and resultant properties of Al/Cu butt joints during CMT method have not yet been revealed scenario. Therefore, it is necessary to frame an investigation on CMT welding-brazing of Al alloy to pure copper in butt joints. The growth of the IMC layer is generally affected by the filler composition and thermal cycle during welding process. The asymmetrical V-groove configuration is designed to improve the feature of the IMC layer at the interface. It should be established information on the cross section, microstructure and mechanical properties of Al/Cu butt joints.

This paper aims at investigating the feasibility of CMT welding-brazing process for Al/Cu butt joints in asymmetrical V-groove configuration. The microstructure and mechanical properties of Al/Cu butt joints are analyzed in detail.

2 Materials and methods

In the present study, 6061 Al alloy and pure copper T2 plates with the thickness of 2 mm, size 100 × 45 mm as the parent metals were used for CMT welding. Table 1 lists chemical composition of 6061 Al alloy and pure copper T2. The filler wire (AlSi12-4047) with the diameter of 1.2 mm was used. The schematic diagram of CMT welding is shown in Figure 1. Table 2 lists CMT welding parameters in this study. The welding current and voltage synchronously increase with increasing the wire feed rate in this study.

Metallographic specimens were prepared from the transverse cross section of butt joints for microstructural examination. All the specimens were ground on silicon carbide papers of 80–2000 grit and then finally polished. The specimens were etched with Keller’s etchant (1.0 ml HF + 1.5 ml HCl + 2.5 ml HNO3 + 95 ml H2O). The microstructure of dissimilar joints was examined using Olympus DSX510 optical microscope and scanning electron microscope (SEM). The compositional analysis was characterized using scanning electron microscope equipped with energy dispersive spectroscopy (EDS). A Philips X-ray diffractometer (XRD, rotating anode type and Cu Kα radiation) was utilized for identifying the phase on the fracture surface. The transverse tensile properties of the butt joints were evaluated on a tensile testing machine (Mode: Zwich/Roell Z050) according to the standard tensile method at room temperature. The tensile specimens were machined in dimension of 80 × 10 × 2 mm. The fracture surface of Al/Cu butt joints was also observed by SEM. The microhardness measurements, using a load of 100 g and keeping time of 15 s, were made across the welds to obtain the microhardness profiles of dissimilar butt joints on the transection.

Table 1

Chemical composition of base metals and filler wire (wt.%).

thumbnail Fig. 1

Schematic illustration of CMT welding of 6061 Al and pure copper.

Table 2

Welding parameters.

3 Results and discussion

3.1 Appearance and cross section

Figure 2 shows the appearance and cross section of Al/Cu butt joints at different rate of filler wire. As shown, the butt joints appear incompleted fusion at the wire feed rate of 4.0 m/min. It is because the low heat input results in insufficient flow and spreading of molten pools on the groove. The heat input increases with increasing the wire feed rate and welding current. With increasing the wire feed rate, the molten filler wire is completely spread on the Cu plate and the surface appearance of the joints becomes flat. The wettability of molten metals becomes better on the groove beside Cu side. From the cross section, the joint consists of three regions: the fusion zone, the Al/Cu brazed interface and the fusion boundary beside Al side. The fusion zone mainly forms by the melted AlSi12 filler wire and Al base metals. Meanwhile, it can be observed a typical brazed feature at the Al/Cu interface. It indicates that the AlSi12 molten metals have good fluidity during welding. As high Si low-melting eutectic alloy, AlSi12 filler wire is generally used as filling materials for dissimilar fusion-brazing. The Si element in the filler wire can improve the fluidity of the weld pool and make the molten metals easily spread at the interface. With the asymmetrical V-groove configuration, the melted AlSi12 filler wire could be spread on the Cu substrate under CMT heat source. It thus results in a fusion-brazing butt joint.

It should be noticed that many globular pores in different size can be observed in the butt joints. Figure 3 presents the porosities near the Al/Cu interface of the joints. It has been known that the defect of porosity is common problem in the Al welded joints. It associates to the bubbles if it cannot escape from the molten pools during welding. At the elevated temperature, it is greatly susceptible for the molten pools to absorb hydrogen [21]. Since the solubility of hydrogen in liquid Al is much larger than that in solid Al, the supersaturated gases would form bubbles in the molten pools. Due to CMT welding with very fast cooling speed, it thereby results in the porosity when the gases are excessively absorbed and the time is not enough for the bubbles to escape at the solidification stage.

thumbnail Fig. 2

The appearance and cross section profile of Al/Cu butt joints.

thumbnail Fig. 3

The porosities in the regions of the butt joints (a) and (b) OM image; (c) and (d) SEM image.

3.2 Microstructure of Al/Cu butt joints

Figure 4 shows the microstructure in the fusion zone of Al/Cu butt joints. As shown in Figures 4a and 4b, the microstructure of the fusion zone consists of α (Al) and secondary phases at the grain boundaries. Many eutectic phases are exhibited in the fusion zone, as shown in Figures 4c and 4d. Table 3 lists the chemical composition of eutectic phases in the test position of the fusion zone. It indicates that the eutectic phases are mainly composed of Al, Cu and Si. It speculates that the eutectic phase mainly contains α (Al) + Si phase and Al2Cu phase. Generally, Si is a strengthening element of Al alloy and the microstructure in the Al–Si alloy mainly consists of α(Al) and α(Al) + Si eutectic phase. Because of the facts that Cu base materials are slightly melted and some Cu atoms diffuse into the molten pool during welding, a certain mass of Cu atoms are detected in the fusion zone. The diffusion coefficient of Cu in Al is larger than that of Al in Cu [22]. When Cu adds to the Al–Si alloy, it does not form any ternary compound and preferentially form Al2Cu phase. The formation of α(Al) and Al2Cu eutectic phase occurs since the eutectic reaction L→α(Al) + Al2Cu happens at 548.3 °C [23]. Furthermore, the ternary eutectic reaction L→α(Al) + Si + Al2Cu could occur at 525 °C with the diffusion and mixture of Cu in the fusion zone. Hence, a large number of Si phase could be distributed in the fusion zone in this study.

Figure 5 shows the microstructure at the interface beside Al side of Al/Cu butt joints. Since the melted AlSi12 liquid metals and Al base metals have good compatibility, the fusion boundary is similar to that of Al welding. Figure 6 shows line scan of the eutectic phases at the interface beside Al side. Table 4 lists the chemical composition in the test position at the interface beside Al side. It demonstrates that the eutectic phases are mainly composed of Al, Cu and Si. The characteristics are similar as that in the fusion zone. It can also be identified as α (Al) + Si eutectic phase and Al2Cu phase. Due to the stirring and diffusion action, Al2Cu phases are also distributed at the boundaries in this region.

Figure 7 shows the microstructure at the Al/Cu interface of the butt joints. As shown, the two-layer IMC layers are exhibited in the interfacial regions. The first IMC layer (Layer I) near the copper is a thin and smooth layer in thickness of less than 5 µm. The second IMC layer is in irregular non-linear and zigzag shape, and some particles are dispersed at the boundaries. Table 5 lists the chemical composition in the interfacial regions. It is speculated that Layer I are mainly composed of Al2Cu and Al4Cu9 phases according to the atom ratio. This is similar to the aforementioned research reported by Xue et al. [24]. It is inferred that some AlCu phases could be contained in Layer II. The particles dispersed at the boundaries near Layer II are also considered as Al2Cu phase. The formation of the reaction layers occurs relevant to the diffusion and mixture between Al and Cu. Since tiny part of Cu base metals are melted, the Cu atoms are diffused and mixed with Al in the joints. When Al and Cu atoms reach the maximum solid solubility, the corresponding IMCs grow at a rapid growth rate in the interfacial regions. It should be pointed out that SEM/EDS technique only provide an approach to examine micro-area composition in the joints. The composition of the reaction layer is very complex. The other possible phases such as AlCu and Al3Cu4 could also be developed in the interfacial regions. Figure 8 presents the line scan at the Al/Cu interface of the butt joints. As shown, the Al content increases gradually, the Cu content decreases gradually from Cu base metal to the fusion zone. Additionally, the results indicate that some Si atoms are merely dissolved at the interface. The content of Si infiltrated into the diffusion layer is very limited since non-metallic properties of Si make it difficult to form IMCs with Cu and Al.

Further XRD investigations are detected to identify the IMC phase structure in the joints. Figure 9 presents the XRD pattern of the butt joints. It can be seen that there are various IMCs involving Al2Cu, Al4Cu9, AlCu and Al3Cu4 in the joints. The XRD results are in agreement the data previously reported for Al/Cu dissimilar welding [25,26]. In Al–Cu system, the Al–Cu phases are categorized to be Al2Cu, Al4Cu9, AlCu and Al3Cu4 corresponding to the atomic concentration. It is considered that the formation of these Al–Cu IMCs associates with their activation energies. The IMCs can form in the sequence of Al2Cu, Al4Cu9, AlCu and Al3Cu4 due to the thermal effect. This further confirms the above microstructural observation.

thumbnail Fig. 4

Microstructure in the fusion zone of Al/Cu butt joints (a) and (b) OM image; (c) and (d) SEM image.

Table 3

Chemical composition of the eutectic phases in the fusion zone (at.%).

thumbnail Fig. 5

Microstructure at the interface beside Al side of Al/Cu butt joints (a) SEM image; (b) is enlarged view of (a).

thumbnail Fig. 6

The line scan at the interface beside Al side of Al/Cu butt joints (a) SEM image; (b) line scans.

Table 4

Chemical composition at the interface beside Al side of Al/Cu butt joints (at.%).

thumbnail Fig. 7

Microstructure at the Al/Cu interface of butt joints (a), (c) and (e) SEM image; (b), (d) and (f) are enlarged view of (a), (c) and (e), respectively.

Table 5

Chemical composition at Al/Cu interface of the butt joints (at.%).

thumbnail Fig. 8

The line scans at the Al/Cu interface of the butt joints.

thumbnail Fig. 9

XRD analysis of Al/Cu butt joints.

3.3 Mechanical properties of butt joints

3.3.1 Tensile strength

Figure 10 shows the ultimate tensile strength (UTS) of Al/Cu butt joints at room temperature. As shown in Figure 10, the UTS of the joints increases at high wire feed rate. The maximum UTS of the joints can reach 108 MPa at the wire feed rate of 5.5 m/min. It demonstrates that the joints with sufficient strength can be achieved in the use of V-groove configuration and AlSi12 filler wire. The fracture path of all the butt joints are propagated along the Al/Cu interface in the tensile test. Figure 11 shows typical macro-morphology of tensile specimen for Al/Cu butt joints. It indicates that the Al/Cu interfacial region is the weak position in the butt joints.

Figure 12 shows the fracture surface of Al/Cu butt joints. As shown in Figures 12a and 12b, it is found that there are many pores in different size on the fracture surface. It is considered that these pores result in the great reduction in the UTS of the joints. The sensitivity of porosity in the joints are obviously associated with wire feed rate. At low wire feed rate, more denser pores are presented at the interface in Al/Cu joints. This could be due to low welding heat input and lack of heat energy so that it is difficult to remove the oxides on the groove of Cu base materials. It is consistent with the above observation in the joints. The fracture mode of the joints is brittle fracture. As shown in Figures 12c and 12d, few pores are observed on the fracture surface. High wire feed rate contributes to pores in the interfacial regions. The fracture surface is smooth with some distinct IMCs. The brittle feature is dominant on the fracture surface of the joints. Nevertheless, it can also be observed some tear ridge and scraggly areas on the fracture surface. The traces of shear deformation indicate that the joints possess higher tensile strength. Table 6 lists compositional analysis of different area on the fracture surface of the joints. They are identified as brittle Al–Cu IMCs. It suggests that these Al–Cu IMCs are responsible for the failure of the joints. Because of their extreme brittleness, the IMC phases attribute to the brittle fracture of the joints. The fracture feature is further revealed through the detection of the IMCs on the fracture surface. Figure 13 shows high-magnification SEM images of the IMCs on the fracture surface. Table 7 lists the composition of these IMCs on the fracture surface, which are also identified as Al–Cu IMCs. It further verifies the fact that the failure of the joints is related with the IMCs. It has been accepted that the strength of the joints is significantly dependent on the IMCs in the interfacial regions of dissimilar joints [24]. Because the coherency between the IMCs and Cu base metals is poor, the brittle feature is always displayed on the fracture surface. As mentioned above, Al2Cu, Al4Cu9, AlCu and Al3Cu4 phases have been examined according to microstructural analysis. The lattice structure of the IMCs is different from that of Al and Cu, which induces the significant difference in mechanical properties between them. Since these IMC phases are fragile and brittle, the stresses fail to be effectively eliminated by plastic deformation of the grains, thereby increasing the cracking susceptibility. Hence, the butt joints are preferentially fractured along the Al/Cu interface accompanied with the brittle feature.

thumbnail Fig. 10

Tensile strength of Al/Cu butt joints at room temperature.

thumbnail Fig. 11

Typical macro-morphology of tensile specimen for Al/Cu butt joints.

thumbnail Fig. 12

The fracture surface of Al/Cu butt joints (a) and (b) SD-C specimen; (c) and (d) SD-E specimen; (e) and (f) SD-F specimen.

Table 6

Chemical composition of the IMCs on the fracture surface (at.%).

thumbnail Fig. 13

The IMCs on the fracture surface of Al/Cu butt joints (a) SEM image; (b) is enlarged view of (a).

Table 7

Chemical composition of the IMCs on the fracture surface (at.%).

3.3.2 Microhardness

Figure 14 shows the microhardness distribution profiles of Al/Cu butt joints. Line 1 and line 2 are two different test lines in the joints. The microhardness is significantly increased at the Al/Cu interface of the joints. It could be ascribed to the formation of brittle and hard IMC layer at Al/Cu interface. As discussed above, various kinds of IMCs are generated at the Al/Cu interface, and the joints thus become brittle. The microhardness in the fusion zone is higher in comparison to the Al base metals. This may be because Cu dissolves and diffuses to form eutectic phases in the fusion zone during welding.

thumbnail Fig. 14

The microhardness distribution profile of Al/Cu butt joints (a) SD-E specimen; (b) SD-F specimen

4 Conclusion

In this study, Al/Cu butt joints are fabricated by CMT welding-brazing process in asymmetrical V-groove configuration. The main conclusions are drawn as follows. The joints with good appearance can be obtained, but there are some pores in the fusion zone. The microstructure in the fusion zone mainly consists of α (Al) and Al2Cu phase accompanied with Si phase. It is observed two-layer IMC layers at the Al/Cu interface. The first IMC layer near the copper is a thin layer in thickness of less than 5 μm. The second IMC layer is in irregular non-linear and zigzag shape, and some particles are dispersed at the boundaries. XRD analysis shows that the joints mainly contain Al2Cu, AlCu, Al3Cu4 and Al4Cu9 phase. The fracture path of the joint is along the Al/Cu interface. The brittle feature is dominant on the fracture surface of the joints. At low wire feed rate, many pores are presented at the interface, making a significant reduction in the UST of the joints. Due to the formation of brittle Al–Cu IMCs, the joints break along the Al/Cu interface at high wire feed rate. The butt joints with sufficient strength can be achieved in the use of asymmetrical V-groove configuration.

Acknowledgments

The authors gratefully acknowledge the National Natural Science Foundation of China (Grant No. 51605216) for the financial support.

References

  1. T. Saeid, A. Abdollah-Zadeh, B. Sazgari, Weldability and mechanical properties of dissimilar aluminum-copper lap joints made by friction stir welding, J. Alloy Compd. 490, 652–655 (2010) [CrossRef] [Google Scholar]
  2. X.L. Zhou, G. Zhang, Y. Shi, M. Zhu, F.Q. Yang, Microstructures and mechanical behavior of aluminum-copper lap joints, Mater. Sci. Eng. A 705, 105–113 (2017) [CrossRef] [Google Scholar]
  3. A. Muhammad Najib, C.S. Wu, W.H. Tian, Effect of ultrasonic vibration on the intermetallic compound layer formation in Al/Cu friction stir weld joints, J. Alloy. Compd. 785, 512–522 (2019) [CrossRef] [Google Scholar]
  4. X. Fei, Y. Ying, L. Jin, H. Wang, S. Lv, Special welding parameters study on Cu/Al joint in laser-heated friction stir welding, J. Mater. Process. Technol. 256, 160–171 (2018) [CrossRef] [Google Scholar]
  5. C.W. Tan, Z.G. Jiang, L.Q. Li, Y.B. Chen, X.Y. Chen, Microstructural evolution and mechanical properties of dissimilar Al–Cu joints produced by friction stir welding, Mater. Des. 51, 466–473 (2013) [Google Scholar]
  6. M. Felix Xavier Muthu, V. Jayabalan, Tool travel speed effects on the microstructure of friction stir welded aluminum–copper joints, J. Mater. Process. Tech. 217, 105–113 (2015) [CrossRef] [Google Scholar]
  7. H.T. Fujii, H. Endo, Y.S. Sato, H. Kokawa, Interfacial microstructure evolution and weld formation during ultrasonic welding of Al alloy to Cu, Mater. Charact. 139, 233–240 (2018) [Google Scholar]
  8. T. Solchenbach, P. Plapper, Mechanical characteristics of laser braze-welded aluminum–copper connections, Opt. Laser Technol. 54, 249–256 (2013) [Google Scholar]
  9. C. Otten, U. Reisgen, M. Schmachtenberg, Electron beam welding of aluminum to copper: mechanical properties and their relation to microstructure, Weld. World. 60, 21–31 (2016) [CrossRef] [Google Scholar]
  10. F. Ji, S.B. Xue, D. Wei, Reliability studies of Cu/Al joints brazed with Zn–Al–Ce filler metals, Mater. Des. 42, 156–163 (2012) [Google Scholar]
  11. A. Esmaeili, H. Zareie Rajani, M. Sharbati, M. Besharati Givi, M. Shamanian, The role of rotation speed on intermetallic compounds formation and mechanical behavior of friction stir welded brass/aluminum1050 couple, Intermetallics 19, 1711–1719 (2011) [Google Scholar]
  12. R. Balasundaram, V.K. Patel, S.D. Bhole, D.L. Chen, Effect of zinc interlayer on ultrasonic spot welded aluminum-to-copper joints, Mater. Sci. Eng. A 607, 277–286 (2014) [CrossRef] [Google Scholar]
  13. J.W. Yang, B. Cao, Investigation of resistance heat assisted ultrasonic welding of 6061 aluminum alloys to pure copper, Mater. Des. 74, 19–24 (2015) [Google Scholar]
  14. S. Babu, S.K. Panigrahi, G.D. Janaki Ram, P.V. Venkitakrishnan, R. Suresh Kumar, Cold metal transfer welding of aluminium alloy AA 2219 to austenitic stainless steel AISI 321, J. Mater. Process. Tech. 266, 155–164 (2019) [CrossRef] [Google Scholar]
  15. M.J. Kang, C. Kim, Joining Al 5052 alloy to aluminized steel sheet using cold metal transfer process, Mater. Des. 81, 95–103 (2015) [Google Scholar]
  16. S.L. Yang, J. Zhang, J. Lian, Y.P. Lei, Welding of aluminum alloy to zinc coated steel by cold metal transfer, Mater. Des. 49, 602–612 (2013). [Google Scholar]
  17. R. Cao, J.H. Sun, J.H. Chen, Mechanisms of joining aluminium A6061-T6 and titanium Ti–6Al–4V alloys by cold metal transfer technology, Sci. Technol. Weld. Joi. 18, 425–433 (2013) [CrossRef] [Google Scholar]
  18. H.T. Zhang, J.K. Liu, Microstructure characteristics and mechanical property of aluminium alloy/stainless steel lap joints fabricated by MIG welding-brazing process, Mater. Sci. Eng. A 528, 6179–6185 (2011) [CrossRef] [Google Scholar]
  19. L. Wan, S. Lv, Y. Huang, Y. Xu, Q. Cui, Effect of hot dip aluminising on interfacial microstructure and mechanical properties of Ti/Al joint by TIG arc welding brazing, Sci. Technol. Weld. Joi. 20, 164–171 (2015) [CrossRef] [Google Scholar]
  20. I. Tomashchuk, P. Sallamand, A. Méasson, E. Cicala, M. Duband, P. Peyre, Aluminum to titanium laser welding-brazing in V-shaped groove, J. Mater. Process. Tech. 245, 24–36 (2017) [CrossRef] [Google Scholar]
  21. P. Mehta Kush, J. Badheka Vishvesh, Hybrid approaches of assisted heating and cooling for friction stir welding of copper to aluminum joints, J. Mater. Process. Tech. 239, 336–345 (2017) [CrossRef] [Google Scholar]
  22. M.N. Avettand Fènoël, G. Racineux, L. Debeugny, R. Taillard, Microstructural characterization and mechanical performance of an AA2024 aluminium alloy-pure copper joint obtained by linear friction welding, Mater. Des. 98, 305–318 (2016) [Google Scholar]
  23. J. Ouyang, E. Yarrapareddy, R. Kovacevic, Microstructural evolution in the friction stir welded 6061 aluminum alloy (T6-temper condition) to copper, J. Mater. Process. Tech. 172, 110–122 (2006) [CrossRef] [Google Scholar]
  24. P. Xue, B.L. Xiao, Z.Y. Ma, Effect of interfacial microstructure evolution on mechanical properties and fracture behavior of friction stir-welded Al–Cu joints, Metall. Mater. Trans. A 46, 3091–3103 (2015) [CrossRef] [Google Scholar]
  25. W.B. Lee, K.S. Bang, S.B. Jung, Effects of intermetallic compound on the electrical and mechanical properties of friction welded Cu/Al bimetallic joints during annealing, J. Alloy Compd. 390, 212–219 (2005) [CrossRef] [Google Scholar]
  26. W. Zhang, Y.F. Shen, Y.F. Yan, R. Guo, Dissimilar friction stir welding of 6061 Al to T2 pure Cu adopting tooth-shaped joint configuration: Microstructure and mechanical properties. Mater. Sci. Eng. A 690, 355–364 (2017) [CrossRef] [Google Scholar]

Cite this article as: Gang Li, Jufeng Song, Xiaofeng Lu, Xiaolei Zhu, Shengyu Xu, Yupeng Guo, Investigation on microstructure and mechanical properties of Al/Cu butt joints by CMT method in asymmetrical V-groove configuration, Metall. Res. Technol. 117, 303 (2020)

All Tables

Table 1

Chemical composition of base metals and filler wire (wt.%).

Table 2

Welding parameters.

Table 3

Chemical composition of the eutectic phases in the fusion zone (at.%).

Table 4

Chemical composition at the interface beside Al side of Al/Cu butt joints (at.%).

Table 5

Chemical composition at Al/Cu interface of the butt joints (at.%).

Table 6

Chemical composition of the IMCs on the fracture surface (at.%).

Table 7

Chemical composition of the IMCs on the fracture surface (at.%).

All Figures

thumbnail Fig. 1

Schematic illustration of CMT welding of 6061 Al and pure copper.

In the text
thumbnail Fig. 2

The appearance and cross section profile of Al/Cu butt joints.

In the text
thumbnail Fig. 3

The porosities in the regions of the butt joints (a) and (b) OM image; (c) and (d) SEM image.

In the text
thumbnail Fig. 4

Microstructure in the fusion zone of Al/Cu butt joints (a) and (b) OM image; (c) and (d) SEM image.

In the text
thumbnail Fig. 5

Microstructure at the interface beside Al side of Al/Cu butt joints (a) SEM image; (b) is enlarged view of (a).

In the text
thumbnail Fig. 6

The line scan at the interface beside Al side of Al/Cu butt joints (a) SEM image; (b) line scans.

In the text
thumbnail Fig. 7

Microstructure at the Al/Cu interface of butt joints (a), (c) and (e) SEM image; (b), (d) and (f) are enlarged view of (a), (c) and (e), respectively.

In the text
thumbnail Fig. 8

The line scans at the Al/Cu interface of the butt joints.

In the text
thumbnail Fig. 9

XRD analysis of Al/Cu butt joints.

In the text
thumbnail Fig. 10

Tensile strength of Al/Cu butt joints at room temperature.

In the text
thumbnail Fig. 11

Typical macro-morphology of tensile specimen for Al/Cu butt joints.

In the text
thumbnail Fig. 12

The fracture surface of Al/Cu butt joints (a) and (b) SD-C specimen; (c) and (d) SD-E specimen; (e) and (f) SD-F specimen.

In the text
thumbnail Fig. 13

The IMCs on the fracture surface of Al/Cu butt joints (a) SEM image; (b) is enlarged view of (a).

In the text
thumbnail Fig. 14

The microhardness distribution profile of Al/Cu butt joints (a) SD-E specimen; (b) SD-F specimen

In the text

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