Mechanism of the Mg3Bi2 Phase Formation in Pb-Free Aluminum 6xxx Alloy with Bismuth Addition
Round 1
Reviewer 1 Report
Good paper. It's a pity do not correlate the work results with machinability
Author Response
Thank you for your comment. In the present paper we were particularly interested in the development and morphology of bismuth phase since bismuth was added in aluminium alloy instead of lead. The machinability will be investigated after further preliminary tests.
Kind regards
Reviewer 2 Report
The article "Mechanism of the Mg3Bi2 Phase Formation in Pb-free Alumi-2 num 6xxx Alloy with Bismuth Addition" presents a study of the structures forming in aluminium alloys depending on the additives used and the cooling method. From the scientific point of view, these are interesting studies.
In the introduction, the authors show aluminium alloys in terms of machinability. The relations presented there between the occurrence of certain structures in aluminium alloys are connected with the concept of machinability, but no arguments in the form of references to research results are presented there to support these theses. Furthermore, one of the main problems of aluminium machinability is the formation of build-up on the cutting edge. It is presented that soft alloy fractions improve machinability, but do they prevent build-up?
In the article the subject of machinability is not investigated but references to machinability are presented in the abstract and the conclusions.
Detail remarks:
In line 164 the sentence is in the personal form, this may be changed.
Figures 5 and 6 are very dark and it should be considered whether this figure could be presented in reverse colour.
The Figure 7a should be completed with the names of the elements.
Conclusions should be formed only on the basis of the research results carried out and references to features that are not researched in the article should be removed.
The literature may be extended and should supplemented by a DOI.
Author Response
We would like to thank you for your remarks and suggestions. We are glad that we could improve the manuscript.
- We have changed the sentence in the line 164.
- Figures 5 and 6 show backscattered electron image (BEI) taken with an scanning electron microscope in which the contrast has been deliberately adjusted to make the bismuth phases more visible. Because other intermetallic phases in the alloy (with silicon and iron) has similar morphology it is difficult to distinguish between them and Bi-phases. Since bismuth has the highest atomic mass (Z-contrast) among all the alloying elements in the alloy, its phases appear bright.
- We have added element names to Figures 7a and b and increased the figures resolution.
- The conclusions have been slightly modified according to your comments for better clarity. The results of our research are also related to the findings of other researchers, which are now cited. To the best of our knowledge and the findings of other researchers, only eutectics with a low melting point (Bi-Mg3Bi2, Tm <260°C) can improve machinability because they melt during cutting, promote the braking of long, stringy chips, and prevent them from build-up on the cutting tool edge. However, the machinability will be investigated after further preliminary tests.
- The literature is supplemented with DOI numbers.
All modifications in the manuscript can be seen using track changes option.
Hoping that the above mentioned changes in the manuscript and our answers satisfy all reviewer comments,
I look forward to hearing from you soon.
Kind regards
Reviewer 3 Report
Dear author, I printed your work on a printer, read it and found that some drawings need improvement. In Figures 3, 7b, 8, 10, 11, you need to increase or decrease the font to improve readability, correct them. I advise you to show in the conclusions which method of melting from three methods to ensure the best machinability and mechanical properties of the aluminum alloy after the introduction of bismuth into the chemical composition. The methods are described in detail, but the discussion from the point of view of practical application needs to be improved. In the list of used literature (References), for a better finding of sources and readability, https://doi.org/... should be given.
Author Response
We would like to thank you for your remarks and suggestions. We are glad that we could improve the manuscript.
- We have improved the quality of Figures 3, 7b, 8, 10, 11 and adjusted the font size.
- The conclusions have been slightly modified according to your comments for better clarity. The results of our research are related to the findings of other researchers, which are now cited. To the best of our knowledge and the findings of other researchers, only eutectics with a low melting point (Bi-Mg3Bi2, Tm < 260°C) can improve machinability because they melt during cutting, promote the braking of long, stringy chips, and prevent them from build-up on the cutting tool edge. However, the machinability will be investigated after further preliminary tests.
All modifications in the manuscript can be seen using track changes option.
Hoping that the above mentioned changes in the manuscript and our answers satisfy all reviewer comments,
I look forward to hearing from you soon.
Kind regards
Round 2
Reviewer 2 Report
Thank you for your answers.
The information about machinability in the abstract is a little misleading as this characteristic is not tested and may be considered for change.
