Effect of Ni Addition on the Interfacial Strength of Al/Cu Dissimilar Welds Produced by Friction Stir Lap Welding
Round 1
Reviewer 1 Report
The present study systematically investigates the effect of Ni addition on the weld strength and interfacial microstructure of Al/Cu dissimilar welds produced by friction stir lap welding. The science is satisfactory and presented results are of considerable interest. In addition, the manuscript is well written and well organized. I'd like to recommend its publication after the following minor issues have been addressed.
- The abbreviation of ‘FSLW’ may be more suitable for ‘friction stir lap welding’.
- In Figure 2: it seems the base metals were damaged during the machining process, will the slits affect the experimental results?
- The abbreviations of intermetallic compounds are inconsistent in the several places, such as Figures 3 and 9.
- In Section 3.3. Examination of Fracture Location, Line 204: it mentioned that a small CuAl2 peak was detected on the Al side, but CuAl2 was not marked in Figure 10.
- Some grammar issues need to be polished, like ‘Al/Cu dissimilar welds are a key technology for reducing…’.
Author Response
Please see the attached file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this study, the effect of adding Ni to stir friction welding of Al-Cu on the joint was investigated. The differences of microstructure and mechanical properties of several joints were studied. This is an interesting work to improve the joining performance of dissimilar materials. However, many scholars have done related research on adding other elements to the joints of dissimilar materials to improve the performance of the joints. These should all be mentioned in the introduction. In particular, Hou et al [1,2] also studied the effect of adding Ni in Al-Cu friction stir welding on the joint. In addition, the surface coating is simpler than recasting. They also found that the addition of nickel reduced the formation of harmful intermetallic compounds. Joint peak stress and elongation are improved. This is consistent with the conclusions of this study. The innovation needs to be emphasized
References:
[1] Hou W.; Shen Z.; Huda N.; Oheil M.; Shen Y.; Jahed H.; Gerlich A.: Enhancing metallurgical and mechanical properties of friction stir butt welded joints of Al–Cu via cold sprayed Ni interlayer. MAT SCI ENG A-STRUCT 2021; 140992. https://doi.org/10.1016/j.msea.2021.140992
[2] Hou W.; Oheil M.; Shen Z.; Shen Y.; Jahed H.; Gerlich A.: Enhanced strength and ductility in dissimilar friction stir butt welded Al/Cu joints by addition of a cold-spray Ni interlayer. J MANUF PROCESS 2020; 573-577. https://doi.org/10.1016/j.jmapro.2020.10.059
My other comments are listed as follows:
- Some studies that are the same as the subject of this manuscript should be mentioned in the introduction and the research gap with them should be pointed out.
- In the introduction, some recent studies about dissimilar material joining technique should be added in order to enrich research background. For example. For example:1) Mechanical properties and interfacial microstructures of magnetic pulse welding joints with aluminum to zinc-coated steel. 2) Mechanical properties and corrosion behavior of galvanized steel/Al dissimilar joints. Archives of Civil and Mechanical Engineering. 2021. 21(4)
- The mechanical properties of experimental copper and newly cast Al-Ni alloys should be mentioned.
- The casting process of Al-Ni alloy should also be described
- We suggest that you include pictures of the sample tensile damage in the text for convincing purposes.
- It is recommended that the conclusion section be summarized in points and briefly explain why.
Author Response
Please see the attached file.
Author Response File: Author Response.pdf
Reviewer 3 Report
In this paper, the microscopicity and mechanical properties of Al/Cu friction stir welds according to the Ni content were studied. Some revisions are suggested before publication.
1. What causes the thickness of the IMC layer to decreased as the Ni content increased? If the welding conditions are the same, it seems that the thickness of the IMC layer should be increased. Does the Ni component impede the diffusion of Cu or Al? Please refer to the relevant content in the text.
2. TEM analysis was performed to determine what composition and phase the IMC layer of each FS weld consisted of according to the Ni content. Have you ever performed component analysis of EDS?
3. In the absence of Ni, the IMC layers of CuAl2 and Cu9Al4 were brittle and fractured. However, in the specimens containing Ni, fracture occurred in Al. The reason is probably because the friction stir joint of Al is much weaker than the IMC layer. Is Al weakening due to grain coarsening in the heat-affected zone?
Author Response
Please see the attached file.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The author has made targeted modifications to the comments raised by the reviewer, and the quality of the manuscript has been significantly improved. It is recommend to be published.
