Influence of Cold Rolling Process and Chemical Composition on the Mechanical Properties and Corrosion Behavior of Zr-Based Metallic Glasses
, Alexander Lubenchenko 2 and Andrey I. Bazlov 1,3Round 1
Reviewer 1 Report
The research work in this manuscript is meaningful for comprehending the structure, mechanical properties, corrosion resistance of Zr50Cu44Al6 and Zr49.5Cu44Al6Nb0.5 after casting and cold rolling processes. I suggest accepting it after making some modifications.
1: What is the "crystalline BMGs" in line 70?
2: Lines 73-80 do not need to be divided into two paragraphs.
3: The angle unit in line 146 is wrong. It should be " 30° and 50°".
4: The 'but' in line 169 is not appropriate, the SBs density and the SBs spacing are reciprocal. they are closely related.
5: The '50%' in line 200 is erroneous and should be corrected.
6: The content of lines 205-207 here is very obtrusive and it is recommended to put it together with the related discussion in Section 4.1.
7: The shear band density and the shear band spacing are the reciprocal of each other, so I don't think it is necessary to plot their relationship with micro-hardness at the same time in Fig.6. Just keep one of them, and can compare A1 and A2 in one plot.
8: It is not appropriate to plot the micro-hardness versus the change in free volume change, it is meaningless. ‘International Journal of Mechanical Sciences 201 (2021) 106469’and ‘Acta Materialia 95 (2015) 236–243’ should be important references. It is recommended to plot the change of micro-hardness (HR10-HR0) versus the free volume change.
Author Response
Dear Reviewer
Thank you very much for your practical comments and attention. We tried to answer your questions carefully. We hope we can handle it.
Response 1: Zr-based BMGs have generally been found to exhibit better corrosion resistance to their crystalline counterparts in most aqueous solutions.
Response 2: Corrected.
Response 3: Corrected.
Response 4: Corrected.
Response 5: The Vickers hardness number of alloy A1 (black line) decreases from 426 HV (R0) to 362 HV (R50).
Response 6: Corrected
Response 7: You are absolutely right, but we wanted it to be clearer and more distinctive for the readers. If you let us keep it.
Response 8: Corrected.
Reviewer 2 Report
The topic is of interest and the manuscript is well written but there are many questions that have to be addressed. An important point is that the manuscript does not contain enough images to provide evidence. It is not good just to show plots. A major revision should be done.
Comments for author File: 
Comments.pdf
Author Response
Dear Reviewer
Thank you very much for your practical comments and attention. We tried to answer your questions carefully. We hope we can handle it.
Response 1: The micrographs were taken at magnification 2000x. With a specified length at different positions along the surface of samples at every thickness reduction, shear band spacing was measured and its average was obtained from 35 times measuring. The average SBs density was calculated as an inverse of the measured average SBs spacing.
Response 2: In our ribbon samples, it was considered that the change in the ribbon density is due to the change of free volume. Therefore, the change of free volume for samples was calculated and plotted based on Archimedes density; ΔVf=(ρ0-ρi)/ρ0
So, we considered the error bar for Archimedes density. Density measurements have been performed ten times at every thickness reduction.
Response 3: Corrected.
Response 4: The relative densities (left columns) of as-cast-R0 for A1 and A2 ribbons (black lines) are near each other and it is about 1.
Density for alloy A1 (R0=7 g/cm3, R10=6.83, R30=6.78, R50=6.52)
Density for alloy A2 (R0=7.36 g/cm3, R10=7.31, R30=7.22, R50=7.17)
Response 5: Redlines and right columns of Fig 4 show that the maximum and minimum amount of FV-change in A2 is about 2.6 (at R50) and 0.58 (at R10), however, these points are 7.1 (at 50) and 2.3 (at R10). The FV content of the deformed metallic glasses increases with increasing the density of the shear band. Alloy A2 indicates lower SBs density and less amounting of FV-change.
Response 6: We don`t have these photos.
Response 7: we had put the as-cast ribbons between two steel plates, (every plate has 0.8 mm thickness, totally 1.6 mm). After laser welding of plates and seal surrounding, a one-dimensional cold rolling process without changing of direction was applied in three thickness reductions by multi-pass gradual reduction (0.02 mm per pass) and a tangential speed 0.055 m/sec until the required degree of thickness reduction was reached. The as-cast ribbon has a thickness of about 30 microns and after R50 we reached about 14 microns. We used 10gf and 25gf for different thicknesses of A1 and A2 ribbons.
Response 8: Figure 2 (SEM images) shows the changes between shear bands density and plastic deformation percent. Vickers hardness test (as a quantitative investigation) was performed on the rolling surface of the sample 10 times without taking photo or SEM for this.
Response 9:
The obtained XPS spectra calculated using method [A.V. Lubenchenko et. all., Applied Surface Science 427 Part A (2018) 711-721]. Information on chemical and phase composition on the layers was obtained by the analysis of peaks produced by elastically scattered electrons. To find of lines O1s, C1s, Zr 3d, Al 2p, Cu 3p [A.V. Naumkin et. all., NIST X-ray Photoelectron Spectroscopy Database, Measurement Services Division of the National Institute of Standards and Technology (NIST) Technology Services, 2008] we used, the values of chemical shifts for oxides. Non-destructive chemical and phase depth profiling of nano-sized films in this investigation was carried out on the base of method [A.V. Lubenchenko et. all., Applied Surface Science 427 Part A (2018) 711-721]. This method enables to determine the depth profiles with a sub-monolayer accuracy using XPS data.
Response 10: BMG alloys generally (rod samples) show high corrosion resistance in H2SO4 solution, but weak corrosion resistance in NaCl and HCl. In this research, we wanted to evaluate and compare the effect of NaCl and Na2SO4 solutions on cold-rolled ribbons Zr-MGs in the presence of different thickness reduction, shear bands, and two chemical compositions.
Response 11: Corrected. We used the mentioned reference. Thank you
Minor comment: Corrected.
Reviewer 3 Report
The manuscript presents regular research devoted to strain-induced rejuvenation phenomenon in metallic glasses as well as Nb microalloying influence on mechanical and corrosion properties of the Zr50Cu44Al6 alloy. Although these results are not surprising to the BMGs society, they agree well with the established knowledge in the area and, as another proof, could be published. However, before the presented manuscript can be considered for publication, an extensive effort of all Authors should be undertaken to improve its technical quality. It is even too early to give it a detailed review. Numerous logical mistakes, nomenclature errors, substantial inconsequence as well as abundant lingual and grammatical errors are too much to be considered for publication this time. The text is suggested to be rewritten carefully and thoroughly in cooperation with all Authors.
Author Response
Dear Reviewer
Response: Thank you very much for your practical comments and attention. My colleagues and I tried to correct the mistakes that you have mentioned for example some grammatical points, text, nomenclature errors, ... . We hope we could handle it.
Reviewer 4 Report
This work investigates the effects of cold rolling on the Zr based metallic glass ribbons. It was found that cold rolling led to softening of the glass due to the formation of free volume. The manuscript appears to have merit, but I have a few comments.
1. Please list the purity of the elements.
2. It is important to mention how far apart the indents were spaced for the hardness testing.
3. In the introduction, the authors briefly discuss how the free volume is related to the structural and mechanical properties of metallic glass. It is strongly recommended that more discussion is added to this section. Some references are given below to help:
Journal of Non-Crystalline Solids 2021, 568, Materials Science and Engineering: A 2020, 771, 138585, Appl. Phys. Lett. 2021, 119.
4. About the hardness data presented in Figure 5, please better describe the hardness of the two alloys. As an example, the hardness is not significantly different (within the error) for the as-cast and cold rolled-R110, but is substantially different for the other two conditions.
5. There are some grammatical issues in the text.
Author Response
Dear Reviewer
Thank you very much for your practical comments and attention. We tried to answer your questions carefully. We hope we can handle it.
Response 1: Pure Zr (99.8%), Cu (99.99%), Nb (99.5%), and Al (99.99%), Added to manuscript.
Response 2: Each reported hardness value is conducted more than 10 times and at a spacing higher than the diameter of the indenter.
Response 3: Corrected as below. We used the mentioned reference in the introduction. Thank you
As mentioned above, Spaepen has proposed a model where the plastic deformation results from a large amount of the stress-driven creation of free volumes by atomic jumps. The local distribution of free volumes is thought to control the deformation, and the fertile sites with a higher free volume content can easily accommodate local shear strains that influence the structural and mechanical properties of the metallic glasses.
Response 4: Corrected in the manuscript. "Changing difference of Hardness between R0 and R10 is less than their difference with higher thickness reductions (R30 and R50). The main reason for this behavior is the work-softening due to the creation of a large amount of free volume. This issue is addressed in the discussion section."
Response 5: My colleagues and I tried to correct the grammatical mistakes that you have mentioned.
Round 2
Reviewer 2 Report
The comments have been addressed and therefore the paper is ready for publication.
Author Response
Dear Reviewer
Thank you for your patience, good comments, and acceptance of the paper.
Reviewer 3 Report
Please see the PDF with the reviewer's comments on the manuscript. They are of various nature: grammatical and spelling errors, essential mistakes, as well as questions to the authors that the reviewer expects them to answer to or react somehow. The reviewer hopes that this work will help the authors to improve the technical quality of their manuscript as well as increase the average level of Metals publications.
Comments for author File: Comments.pdf
Author Response
Dear Reviewer
The authors thank you so much for your accurate correction and logical guidance. We did our best to correct the grammatical and technical mistakes that you have mentioned in the manuscript.
There are some small notes:
-About the re-melted at least five times to ensure chemical uniformity: we did not do XRF after melting. However, the mass of selected alloys was the same before and after melting.
-About multi-pass gradual reduction (0.02 mm per pass): You are right. It was not possible to measure the thickness of ribbons per pass. We measured the thickness reduction of steel plates, continuously. 0.02 mm per pass is related to steel plates.
-Some displacements were for the change in the word software. Those were correct in the main word.
Kind Regards,
Authors
Round 3
Reviewer 3 Report
The manuscript's quality increased significantly. I could only recommend now to change 'GFA' in line 86 to 'critical diameter' as GFA is not measured in [mm]. There is also 'Nano' in line 369 that yet seems to be overlooked.
