Microstructure, Texture Evolution, and Mechanical Properties of MDFed GWZ Alloy Containing LPSO Phases on the Condition of High and Low Temperature Cycle Deformation
Round 1
Reviewer 1 Report
The presented paper studies the effect of several MDF passes and heat treatment on the microstructure evolution and following mechanical properties of Mg-13Gd-4Y-2Zn-0.5 Zr magnesium alloy. The authors used a novel method to prepare the material, although it seems a little bit time consuming with 8-hour annealing after each MDF pass. The microstructure is studied by light optical microscopy, scanning electron microscopy (SEM images and EBSD) and special attention is paid to the particles (studied by TEM) and texture evolution (EBSD). The mechanical properties are examined by the means of tensile tests.
Generally, the topic is timely but major revision needs to be done before the paper can be accepted.
The English language of the manuscript should be significantly improved. Moreover, the use of abbreviations such as MDF, Mg, UTS, etc. should be first declared and then used. Throughout the manuscript, some of the abbreviations are declared more than once, some of them are declared (for example for magnesium) but then not used in the manuscript, or sometimes used sometimes not. These should be unified. A comprehensive proofreading should be done. In the Abstract, line 18: what do you mean under “undynamic recrystallized”? Shouldn’t that be dynamic unrecrystallized? Meaning that the grains are not recrystallized? Or did you mean that the recrystallization wasn’t a dynamic process? On page 3 lines 100-105 –please try to simplify the text. It took a lot of effort to understand the setup and conditions. Correct the figure caption of Figure 4 – there is missing and misleading notation. Moreover, the notation of (a), (b), etc. in Figure 4 cannot be seen. You are writing that plate-like precipitates occurred after 2nd MDF pass. However, some of these can be seen in Fig. 4b – after 1 MDF pass in the big unDRX grains. Can you comment on that? The effect of the annealing on the grain size and distribution should be discussed. At the same time, figure 6 could be enlarged. I understand the need to use some criteria to distinguish the DRX and un-DRX grains. However, the criteria to use 10 um could not be the best choice. Exactly this leads to the result, that after 2nd MDF pass the volume fraction of unDRX grains is established to be 87%, which is misleading information. If one was just reading the text one could think that the microstructure contains big grains. Which according to Fig 4 is not the case. The microstructure is nice homogeneous with grain size around 20 um. In my opinion, it is a nicely recrystallized structure, where grain growth occurred. Therefore, in my opinion, some reconsideration is needed regarding the criteria if recrystallization. An orientation triangle is needed in Figure 10. What was the area measured for the texture plots (Fig .11)? It seems to me that it was rather too small to get statistically relevant data. In Figure 12 the results of the tensile test conducted at RT are shown. Is it right? If yes, the name of the x-axis is misleading, it seems that the deformations were conducted at different temperatures. It should be corrected. Maybe use the number of MDF passes. Were these results obtained before annealing or after annealing? Please, specify. Line 299 – where the information about mechanical properties come from?Author Response
Reviewer #1
The presented paper studies the effect of several MDF passes and heat treatment on the microstructure evolution and following mechanical properties of Mg-13Gd-4Y-2Zn-0.5Zr magnesium alloy. The authors used a novel method to prepare the material, although it seems a little bit time consuming with 8-hour annealing after each MDF pass. The microstructure is studied by light optical microscopy, scanning electron microscopy (SEM images and EBSD) and special attention is paid to the particles (studied by TEM) and texture evolution (EBSD). The mechanical properties are examined by the means of tensile tests.
Generally, the topic is timely but major revision needs to be done before the paper can be accepted.
The English language of the manuscript should be significantly improved. Moreover, the use of abbreviations such as MDF, Mg, UTS, etc. should be first declared and then used. Throughout the manuscript, some of the abbreviations are declared more than once, some of them are declared (for example for magnesium) but then not used in the manuscript, or sometimes used sometimes not. These should be unified. A comprehensive proofreading should be done. In the Abstract, line 18: what do you mean under “undynamic recrystallized”? Shouldn’t that be dynamic unrecrystallized? Meaning that the grains are not recrystallized? Or did you mean that the recrystallization wasn’t a dynamic process? On page 3 lines 100-105-please try to simplify the text. It took a lot of effort to understand the setup and conditions. Correct the figure caption of Figure 4-there is missing and misleading notation. Moreover, the notation of (a), (b), etc. in Figure 4 cannot be seen. You are writing that plate-like precipitates occurred after 2nd MDF pass. However, some of these can be seen in Fig. 4b-after 1 MDF pass in the big unDRX grains. Can you comment on that? The effect of the annealing on the grain size and distribution should be discussed. At the same time, figure 6 could be enlarged. I understand the need to use some criteria to distinguish the DRX and un-DRX grains. However, the criteria to use 10 um could not be the best choice. Exactly this leads to the result, that after 2nd MDF pass the volume fraction of unDRX grains is established to be 87%, which is misleading information. If one was just reading the text one could think that the microstructure contains big grains. Which according to Fig 4 is not the case. The microstructure is nice homogeneous with grain size around 20 um. In my opinion, it is a nicely recrystallized structure, where grain growth occurred. Therefore, in my opinion, some reconsideration is needed regarding the criteria if recrystallization. An orientation triangle is needed in Figure 10. What was the area measured for the texture plots (Fig .11)? It seems to me that it was rather too small to get statistically relevant data. In Figure 12 the results of the tensile test conducted at RT are shown. Is it right? If yes, the name of the x-axis is misleading, it seems that the deformations were conducted at different temperatures. It should be corrected. Maybe use the number of MDF passes. Were these results obtained before annealing or after annealing? Please, specify. Line 299-where the information about mechanical properties come from?
Answer:
Dear Reviewer:
Thank you for the your comments concerning our manuscript entitled “Microstructure, texture evolution and mechanical properties of MDFed GWZ alloy containing LPSO phases on the condition of high and low temperature cycle deformation”. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding to our researches. We have studied comments carefully and have made correction which we hope meet with approval. The main corrections in the paper and the responds to the reviewer’s comments are as following:
We have unified the abbreviations such as MDF, Mg, UTS, etc, and presented them in the revised manuscript. We have done a comprehensive proofreading, the grains denoted as “undynamic recrystallized (DRXed)”refer to the phenomenon of recrystallization during thermal deformation. And the big undeformed grains were denoted as DRXed grains in the MDF processing. In the processing of thermal deformation, the big undeformed and small grains are defined as unDRXed grains and DRXed grains, respectively [1]. We have carefully checked the text about the condition of MDF processing, and simplified the condition as soon as possible. We have corrected the caption of Figure 4, and the results of the revision can be seen in the revised manuscript. We have double checked the plate-like precipitates occurred after 2nd pass, and the plate-like precipitates were not been seen in the big unDRX grains after 1 MDF pass. In order to increase persuasion, we also perform SEM analysis. It can be clearly seen that the morphology of the precipitated phases is different, and you think that the plate-like precipitates that appeared in the 1st pass are confirmed to be lamellar LPSO phases. The purpose of the annealing treatment mentioned in thepaper is to uniform the deformed microstructure of the previous pass. It is well known that during the annealing process, the grains gradually grow and are uniformly distributed at the proper temperature. We don’t think it necessary to discuss in the
Figure 1. The OM and SEM images of different passes. (a,c) 1 pass, (b,d) 2 passes.
In the paper, we used the criteria of 10 μmto distinguish the DRX and unDRXed grains. As you mentioned in the comments, the criteria to use 10 μm might not be the best choice. We observed the microstructure and chose the criteria of 10 μm in the MDF processing on the condition of high and low temperature cycle deformation in order to compare with the conventional MDF on the condition of decreasing temperature (the paper was submitted to another journal). Moreover, Zhang et. al [1] investigated that the effects of repetitive upsetting-extrusion parameters on microstructure and texture evolution of Mg-Gd-Y-Zn-Zr alloy, and they defined the dynamic recrystallized (DRXed) grains as grains with less than 10 μm in diameter. Zhang et. al [2] also investigated that the effects of repetitive upsetting extrusion on the microstructure and texture of GWZK124 alloy under different starting temperatures, and DRXed grains were defined as grains with average grain size of ≤ 10 μm. We have added the orientation triangle to Figure 10, and it can be seen in the revised manuscript. The area was 590 μm× 567 μm for the texture plots (Figure 11). The micro-texture were measured by the software of EBSD and analyzed by the software of OIM, so we thought we could get statistically relevant data. The results of the tensile tests were conducted at RT as shown in Figure 12. These results were obtained before annealing, in other words, the values of tensile properties at RT after different passes. In order to eliminate the readers’confusion, we have corrected the name of the x-axis of Figure 12. In addition, the information about mechanical properties (UTS:357 MPa, TYS:294 MPa) were from the another paper (the paper was submitted to another journal).
References
[1] Z.J. Yu, Y.D. Huang, W.M. Gan, Z.Y. Zhong, N. Hort, J. Meng, Effects of extrusion ratio and annealing treatment on the mechanical properties and microstructure of a Mg-11Gd-4.5Y-1Nd-1.5Zn-0.5Zr (wt%) alloy, J Mater Sci, 52 (2017) 6670-6686.
[2] G.S.Zhang, Z.M. Zhang, X.B. Li and et al, Effects of repetitive upsetting-extrusion parameters on microstructure and texture evolution of Mg-Gd-Y-Zn-Zr alloy, Journal of alloys and compounds, 790 (2019) 48-57.
[3] G.S.Zhang, Z.M. Zhang, Y.Z. Meng and et al, Effects of repetitive upsetting extrusion on microstructure and texture evolution of GWZK124 alloy under different starting temperatures, Materials, 2019.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this work, the microstructure, texture evolution and mechanical properties of MDFed Mg-13Gd-4Y-2Zn-0.5Zr (wt%) alloy on the condition of high and low temperature cycle deformation have been studied. The design of experiments has been done carefully and all the findings have been analysed in detail. However, before further consideration, the following issues should be addressed:
Page 2 line 57, low-cost or low-cast? In the introduction section, the role of stacking fault energy on the softening mechanisms such as recrystallization and recovery is missing. This aspect can be explain using the following work:Materials Science and Engineering A, Volume 696, 1 June 2017, Pages 366-373
Why Mg-13Gd-4Y-2Zn-0.5Zr alloy is denoted as GWZ? If this name is commercial, it should be avoided. Which atmosphere is used for preheating? In Figure 4, 5,10, for the labels which are drawn in the images, a white background should be used to make them readable. In Figure 7, there some unidentified peaks in the XRD patterns. Please justify them.Author Response
Reviewer #2
In this work, the microstructure, texture evolution and mechanical properties of MDFed Mg-13Gd-4Y-2Zn-0.5Zr (wt%) alloy on the condition of high and low temperature cycle deformation have been studied. The design of experiments has been done carefully and all the findings have been analysed in detail. However, before further consideration, the following issues should be addressed:
Page 2 line 57, low-cost or low cast? In the introduction section, the role of stacking fault energy on the softening mechanisms such as recrystallization and recovery is missing. This aspect can be using the following work:
Materials Science and Engineering A, Volume 696, 1 June 2017, Pages 366-373.
Why Mg-13Gd-4Y-2Zn-0.5Zr alloy is denoted as GWZ? If this name is commercial, it should be avoided. Which atmosphere is used for preheating? In Figure 4, 5, 10, for the labels which are drawn in the images, a white background should be used to make them readable. In Figure 7, there some unidentified peaks in the XRD patterns. Please justify them.
Answer:
Dear Reviewer:
Thank you for the your comments concerning our manuscript entitled “Microstructure, texture evolution and mechanical properties of MDFed GWZ alloy containing LPSO phases on the condition of high and low temperature cycle deformation”. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding to our researches. We have studied comments carefully and have made correction which we hope meet with approval. The main corrections in the paper and the responds to the reviewer’s comments are as following:
We have carefully checked it, and corrected low cast to low cost, and reworded in the revised manuscript. Based on your suggestions, we have addedthe role of stacking fault energy on the softening mechanisms such as recrystallization and recover to the revised manuscript. According to the standard of ASTM, we denoted Mg-13Gd-4Y-2Zn-0.5Zr alloy as GWZ alloy. The rare elements of Mg-RE-Zr alloy in the paper were consisting of Gd, Y. The element of Gd was represented by G, the element of Y was represented by W, the element of Zr was represented by Z. Therefore, we denoted Mg-13Gd-4Y-2Zn-0.5Zr alloy as GWZ alloy and the name was non-commercial. To increase persuasion, we have also searched some literature. Among these references, Ramezani et al. [1] denoted Mg-8.1Gd-4.3Y-1.6Zn-0.4Zr alloy as GWZ alloy, Zhang et al. [2] denoted Mg-12.1Gd-4.0Y-2.2Zn-0.34Zr alloy as GWZK124 alloy. Liao et al. [3] denoted Mg-10Gd-3Y-0.4Zr alloy as GW103K. In the reheating process, we mainly used the resistance furnace to preheat the experimental samples, and the atmosphere was air. In Figure 4, 6, 10, for the labels which are drawn in the images, we have used a white background to make them readable. We have re-done the XRD experiments and identified peaks in the XRD patterns. Diffraction peaks less than 20 degrees are air diffraction peaks, and we have not calibrated. The results are presented in the revised manuscript.
Reference
[1] S.M. Ramezani, A. Zarei-Hanzaki, H.R. Abedi, A. Salandari, P. Minarik, Achievement of fine-grained bimodal microstructures and superior mechanical properties in a multi-axially forged GWZ magnesium alloy containing LPSO structures, J. Alloys. Compd. 793 (2019) 134-145.
[2] Guanshi Zhang, Zhimin Zhang, Yingze Meng, Zhaoming Yan, Xin Che, Xubin Li, Effects of repetitive upsetting extrusion on the microstructure and texture of GWZK124 alloy under different starting temperature, Materials. 15 (2019).
[3] H.G. Liao, P.H. Fu, L.M. Peng, J. Li, S.Q. Zhang, G.Q. Hu, W.J. Ding, Microstructure and mechanical properties of laser melting deposited GW103K Mg-RE alloy, Mater. Sci. Eng. A 687 (2017) 281-287.
Author Response File: Author Response.pdf
Reviewer 3 Report
This research aimed to enhance the mechanical properties of Mg-13Gd-4Y-2Zn-0.5Zr alloy by improving micro-structure with refined grains through low to high temperature cycle deformation (annealing treatment) without increasing multi-directional forming (MDF) passes.
Overall the mechanical properties was found to be increased effectively than that of conventional method.
But few doubts need to be cleared.
Figure 1(b) is little confusing. it shows the material is annealed before go into subsequent passes. For ex. Is it using temperature T2 or any other temperature in the first pass. Because compared to Figure 1(a), the only difference is annealed treatment cycle in Figure 1(b). Please explain little bit more here where the figure is cited in the paper.
It looks Table 1 and Figure 2 are over lapping. Please fix it.
line 108: mention 1-3 and X-Z in subscript as mentioned in Eq.(1)
Table 2: '4ed' correct to 4th Pass.
Figure 4: Please mention caption about (e), (f), (g) and (h). Please make sure that the figures are captioned little confusing. It looks 50 micro meter scale left side and 10 micro meter right side. is it just magnification in each pass? is it so the naming looks wrong in caption. Please check.
Figure 5: To calculate the grain sizes, SEM image at what magnification scale was used. For ex. 50 or 10 micro meter. Please mention it here.
The paper can be accepted after doing minor modifications.
Thank You.
Have a nice day.
Author Response
Reviewer #3
This research aimed to enhance the mechanical properties of Mg-13Gd-4Y-2Zn-0.5Zr alloy by improving micro-structure with refined grains through low to high temperature cycle deformation (annealing treatment) without increasing multi-directional forming (MDF) passes.
Overall the mechanical properties was found to be increased effectively than that of conventional method.
But few doubts need to be cleared.
Figure 1(b) is little confusing, it shows the materials is annealed before go into subsequent passes. For ex. Is it using temperature T2 or any other temperature in the first pass. Because compared to Figure 1(a), the only difference is annealed treatment cycle in Figure 1(b). Please explain little bit more here where the figure is cited in the paper.
It looks Table 1 and Figure are over lapping. Please fix it.
Line 108: mention 1-3 and X-Z in subscript as mentioned in Eq.(1).
Table 2: ‘4ed’ corrected to 4th Pass.
Figure 4: Please mention caption about (e), (f), (g) and (h). Please make sure that the figure are captioned little confusing. It looks 50 micro meter scale left side and 10 micro meter right side, is it just magnification in each pass? Is it so the naming looks wrong in caption. Please check.
Figure 5: To calculate the grain size, SEM images at what magnification scale was used. For ex. 50 or 10 micro meter.Please mention it here.
The paper can be accepted after doing minor modifications.
Thank you.
Have a nice day.
Answer:
Dear Reviewer:
Thank you for the your comments concerning our manuscript entitled “Microstructure, texture evolution and mechanical properties of MDFed GWZ alloy containing LPSO phases on the condition of high and low temperature cycle deformation”. Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding to our researches. We have studied comments carefully and have made correction which we hope meet with approval. The main corrections in the paper and the responds to the reviewer’s comments are as following:
In order to eliminate the readers' confusion and make the readers better understand the differences of conventional MDF and high and low temperature cycle deformation, we have modified Figure 1. The temperature of homogenization treatment and MDF processing in conventional MDF processing are the same as in high and low temperature cycle deformation. Regarding the overlappingof Table 1 and Figure 2, we have revised it in the revised We mentioned 1-3 and X-Z in subscript as mentioned in Eq.(1), where H1, H2, H3 and HX, HY, HZ represent the initial and final heights of X, Y, Z direction, respectively. They are presented in page 4 line 111-112. We have corrected ‘4ed’to 4th pass in Table 2. We have carefully checked Figure 4, and corrected the name of Figure 4. Figure 4(a), (c), (e) and (g) are presented the OM images with the magnification of 200 after different MDF passes. Figure 4(b), (d), (f) and (h) are presented the OM images with the magnification of 1000 after different MDF passes. We used the OIM software to calculate the grain sizes, and the inverse pole figures (IPF) were presented in Figure 10 analyzed by the software of electron backscatter diffraction (EBSD).
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors answered the majority of my questions. The manuscript can be published in the present form.
