Phase Formation, Microstructure, and Mechanical Properties of Ni-Cu Bimetallic Materials Produced by Electron Beam Additive Manufacturing
, Denis Gurianov, Andrey Vorontsov, Evgeny Knyazhev, Alexander Panfilov, Andrey Chumaevskii, Nikolai Savchenko, Sergey Nikonov, Valery Rubtsov and Evgeny KolubaevRound 1
Reviewer 1 Report
The authors using two strategies to build the Ni-Cu system gradient bimetallic part. They investigated the microstrucutre and mechnical property. They also discussed the formation of sharp and smooth interface between the bronze and the heat-resistant nickel alloy. The experimental design shows some innovation. However, the reviewer suggests that the authors should delete some content for the type 1. Just showing the result for type 1 is enough because these are lots of macrodefects that making it no meaning. For the type 2 building part, how to control the formation of the mechanical mixing area should be considered. The reviewer suggests the authors to revise this manuscript and then resubmit it.
Author Response
1. Authors believe that it is necessary to save information about samples of the first type. The studies of the formation of bimetallic samples of the first and second type show that in both the first and second cases there are a number of positive and negative aspects. The negative aspect for the bimetals of the first type is associated with the presence of pores; for the second type of bimetals - inhomogeneity of the structure in the transition zone.
Samples of the second type in addition to the obvious advantages in the absence of defects have a significant disadvantage, since the intensive mixing of components in the gradient zone leads on the one hand to a decrease in the strength of the nickel alloy in the boundary area, and on the other hand should lead to a decrease in the heat removal from the working area of the bronze during operation. Therefore, in further works it is necessary to modernize the technology of obtaining samples to eliminate these drawbacks.
The advantage of samples of the first type is the hint of building a narrow interface between dissimilar materials. Further optimization of technological process will be realized, which may result in defect-free products without extensive mixing of heterogeneous materials.
In the following work, by changing the geometry of filament input into the melt bath, it is planned to ensure that all irregularities on the surface of the nickel part of the sample are evenly filled with material while maintaining both the minimum length of the border between the two parts and a defect-free structure. This can be done by sequential printing with the specimen tilted or by alternating printing in several successive small fragments. In this way the advantages of the first and second types of samples will be provided and their disadvantages will be eliminated. Such work which will logically continue the research on formation of Ni-Cu bimetallic product of the first type.
In the present form, the results obtained can be the basis for the development of the technology of creating inseparable joints for the production of articles, including the peculiarities of the formation of the structure.
2. A more detailed study of the influence of technological parameters on the formation of the mechanical mixing area and ways to control this process is planned for the future works.
Reviewer 2 Report
This is an interesting paper concerning additive manufacturing using two different strategies. The article is well written and all the results and discussion part are well displayed. I would suggest it be published with just minor editing on the text.
1. Line 88-90; the authors need to cite references to support.
2. Line 95, another paragraph would be readily readable.
3. Line 102-103, the authors mentioned twice [GRCop-42]
4. Figure 2, it should be (d-h) instead of (c-h)
5. The abbreviation of ref[40] should be double-checked.
Author Response
- Line 88-90; the authors need to cite references to support.
Corrected. Added to support of two references [22, 23]
- Line 95, another paragraph would be readily readable.
We agree with the comment. Changes have been made to page 2.
- Line 102-103, the authors mentioned twice [GRCop-42]
Corrected
- Figure 2, it should be (d-h) instead of (c-h)
Corrected
- The abbreviation of ref[40] should be double-checked.
Corrected
Reviewer 3 Report
The manuscript submitted by Kseniya Osipovich presents the phase formation, microstructure and mechanical properties of a Ni-Cu system produced by electron beam additive manufacturing. The presented idea, has potential, but must be fundamental improved before publication. In the title a “gradient” of material is suggested, gradient not found in the manuscript text. The paper describes at length the used method and the suppositions about the layer deposition, omitting interpretation of micrographs from fig. 4 to give an example. The EDX lines are explained as different behaviour but is seems to be the same in both cases. I am not convinced by the results of X-ray – how it was analysed only the interface? Figure 8 is not explained.
Author Response
In the title a “gradient” of material is suggested, gradient not found in the manuscript text.
Corrected
The paper describes at length the used method and the suppositions about the layer deposition, omitting interpretation of micrographs from fig. 4 to give an example.
We agree with the comment. Corrections from page 6 have been made.
The EDX lines are explained as different behaviour but is seems to be the same in both cases.
Moving away from the interface, the nickel matrix shows a concentration of elements comparable to the raw material composition (Figure 5a). This structure of the transition zone is optimal in terms of preserving the high strength of the nickel alloy and the thermal conductivity of the copper alloy. For the second type of samples, the mutual dissolution of the nickel alloy and copper was most intense due to the chosen printing strategy II (Figure 5b). In this case, due to the copper layer next to the nickel layer with a sufficiently high temperature of the latter, a more intense diffusion of components occurs. And because the subsequent nickel layer partially melts the underlying nickel layer and a small part of its boundary with the copper layer, there is a mechanical mixing of the components. Thus, there is a jump change of 25 % Cu in the nickel region and a 20 % change of Ni in the bronze region. As a result, an extended interface zone is formed, as shown in Figure 5b.
I am not convinced by the results of X-ray – how it was analysed only the interface?
A: Thank you. In order to determine the phase composition from the interface, a sample from this interface was cut out. The surface of this sample was grinded and, after visual assessment for the presence of two phases, an X-ray diffraction analysis was carried out. For visual evaluation, the criterion was the presence of contrasting areas of different colors in equal parts. The orange hue characterized the bronze area, while the metallic gray hue characterized the nickel alloy area. Information about this has been added to Materials and Methods.
For this purpose, five samples were cut from different structural areas: two from the cop-per and two from the nickel matrix areas and one from their interface area.
Figure 8 is not explained.
Corrections from page 10 have been made.
Round 2
Reviewer 3 Report
The authors have amended properly the manuscript. The manuscript can be published.
Author Response
No notes
