Fe-X-B-Cu (X = Nb, NiZr) Alloys Produced by Mechanical Alloying: Influence of Milling Device
Round 1
Reviewer 1 Report
Dear Authors some explanations should be add to your investigations.
- Please add the weight of charge (samples) introduced to mill.
- Short explanation on experiments repeating, number of trials for each variants P7-A, P7-B, etc should be add to paper.
- For data on tables 1, 2, 3, 4, how many samples were detected.
- Short explanations for four heating rates and results in the figure 7 should be add to paper, maybe by modification of figure legend.
- Capture of figure 7 X axis should be improve. Probably value 1000 should be use not 0.001.
- The sigh / is not necessary in the table 6 after E (energy).
- Equation 4 - what means r.
- How Authors define the period. Please add some explanations.
- Please add reference refer to bibliography for total time in the SPEX (page 10).
- Reference to equivalent milling time is 100, Is it correct?
Author Response
We send our answer in the attached pdf file. We agree all comments.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The study is very interesting for the powder metallurgy community, it shows comparison of shaker and planetary milling.
However, the manuscript needs improvement before publication.
Please see the annotations in the attached pdf file for revising the draft.
Comments for author File: Comments.pdf
Author Response
We send our answers in the attached pdf file. We agree all comments.
Fuethermore, the modifications have been introduced in the revised version of the manuscript.
Author Response File: Author Response.pdf
Reviewer 3 Report
The work reports the authors' findings on the influence of the planetary mill and shaker mill (SPEX 8000) milling devices in the microstructural evolution of two Fe-X-B-Cu (X=Nb, NiZr) alloys produced by mechanical alloying (MA). Microstructural analysis by X-ray diffraction detects the formation of a Fe rich solid solution. In the Fe-Nb-B-Cu alloy produced in the shaker mill also appears a Nb(B) minor phase, whereas in the Fe-NiZr-B-Cu alloy produced in the planetary mill a minor disordered phase is formed. The comparative study regarding the energy transferred per unit of time in both devices determines that the shaker mill is more energetic. This fact explains that in the Fe-Nb-B-Cu alloy Nb has not been introduced in the main Fe rich phase, whereas in the Fe-NiZr-B-Cu alloy milled in the shaker mill was formed the highly disordered phase. With regard to thermal analysis, the values of the apparent activation energies of the main crystallization process (above 200 kJ/mol) correspond to the crystalline growth of the nanocrystalline Fe rich phase.
There are number of concerns that should be addressed before the paper can be considered for publication:
- The description on milling process is too rough!! For example, the experiments were performed in inert Ar atmosphere. Is this means the ball mills are located inside the Ar-filled glove box? or the vials were only sealed inside Ar-filled glove box!! The authors claimed he initial filling factor was close to one half. It is more clear to provide the ball to powders ratio. Is ball to powder ratio is same for both milling tools?
- This work presents the phase formation in mechanically alloyed Fe-X-B-Cu (X=Nb, NiZr) alloys by using different milling device- planetary mill and shaker mill (SPEX 8000). Most of XRD and DSC data and results have been published by present authors in “AIP Advances” (8, 047704 (2018); https://doi.org/10.1063/1.4994144).
|
(3) The density of dislocation was calculated from crystallographic parameters by equation: ρ = 2 √3 (ε/Lb). The statement is not appropriate because the strain ε is also obtained by calculation. The author should perform the TEM observation on these mechanically alloyed powders and measure the dislocation density from the direct evidence of TEM results. |
- The author claimed the EDX data indicates that the contamination from the milling tools is lower (1.5 at.%). How is the error range of EDX measurement? Is this the Fe contamination? It is hard to convince the readers that the contamination from milling tool is so low, especially for the powders milled by SPEX shaker ball mill after 80 hours. Although the experiments were performed in inert Ar atmosphere, the oxygen accumulation from milling atmosphere can’t be neglected for 80 h as-milled powders. The oxygen content of as-milled powders should report.
- The authors present detailed analysis about the transfer of energy in both milling devices. For shaker ball mill, the calculation of kinetic energy/mass powder ratio is based on the frequency of 14.6Hz = 876 r.p.m, which is provided by the manufacturer. Because this is the first step of calculation, the accuracy of this value is very important. Therefore, the author should report the detailed method or procedure that the manufacturer used to obtain this value.
Comments for author File: Comments.pdf
Author Response
Reviewer 3:
The work reports the authors' findings on the influence of the planetary mill and shaker mill (SPEX 8000) milling devices in the microstructural evolution of two Fe-X-B-Cu (X=Nb, NiZr) alloys produced by mechanical alloying (MA). Microstructural analysis by X-ray diffraction detects the formation of a Fe rich solid solution. In the Fe-Nb-B-Cu alloy produced in the shaker mill also appears a Nb(B) minor phase, whereas in the Fe-NiZr-B-Cu alloy produced in the planetary mill a minor disordered phase is formed. The comparative study regarding the energy transferred per unit of time in both devices determines that the shaker mill is more energetic. This fact explains that in the Fe-Nb-B-Cu alloy Nb has not been introduced in the main Fe rich phase, whereas in the Fe-NiZr-B-Cu alloy milled in the shaker mill was formed the highly disordered phase. With regard to thermal analysis, the values of the apparent activation energies of the main crystallization process (above 200 kJ/mol) correspond to the crystalline growth of the nanocrystalline Fe rich phase.
There are number of concerns that should be addressed before the paper can be considered for publication:
- The description on milling process is too rough!! For example, the experiments were performed in inert Ar atmosphere. Is this means the ball mills are located inside the Ar-filled glove box? or the vials were only sealed inside Ar-filled glove box!! The authors claimed he initial filling factor was close to one half. It is more clear to provide the ball to powders ratio. Is ball to powder ratio is same for both milling tools?
Answer:
We rewrite the information about the milling process. We add information about sealed jars-vials and provide the ball-to-powder weight ratio. The same for both devices.
The experiments were performed in jars sealed inside Ar-filled glove box to prevent oxidation.
The milling (10 g of powders) was performed in both devices with Cr-Ni steel jars (45 ml capacity) and balls (12 mm diameter) for 5, 20 and 80 hours. The initial filling factor was close to one half. In SPEX the frequency is 14.6Hz = 876 r.p.m. (revolutions per minute, data provided by the manufacturer), whereas in the P7 the selected frequency of rotation of the platform, Ω, and jars, ω, is the same, 600 r.p.m. The R radius of the platform (measured from the geometric center of the jar position to the center of the platform) of the P7 is R = 7 cm and the internal radius of the jars r = 1.7 cm. The internal radius of the SPEX jar is 2.1 cm. The ball radius Rb is 0.6 cm. The ball to powder weight ratio, BPR, used in both devices has been the same: 5.
- This work presents the phase formation in mechanically alloyed Fe-X-B-Cu (X=Nb, NiZr) alloys by using different milling device- planetary mill and shaker mill (SPEX 8000). Most of XRD and DSC data and results have been published by present authors in “AIP Advances” (8, 047704 (2018); https://doi.org/10.1063/1.4994144).
Answer: It is correct. Nevertheless, in the new manuscript we analyze the process (5h, 20h, 80 h) and we compare the results obtained in both devices taking into account an energy transfer model. We also analyze the activation energy by DSC. Previous work analyzes only samples after 80h milling and provides magnetic analysis of these samples. We add some ramek in the manuscript.
DSC after 80 h of milling were reported on ref. [17]. Here we discuss the process evolution and the kinetic analysis.
|
(3) The density of dislocation was calculated from crystallographic parameters by equation: ρ = 2 √3 (ε/Lb). The statement is not appropriate because the strain ε is also obtained by calculation. The author should perform the TEM observation on these mechanically alloyed powders and measure the dislocation density from the direct evidence of TEM results. Answer: We add a comment and a refence. In our university, we don’t have a TEM device for materials observation. It should be remarked than XRD methods can provide higher values of the dislocations density than transmission electron microscopy (TEM) analysis [16]. TEM values are considered as more accurate due to direct observation.
17. Takebayashi, T.; Kunieda, T.; Yoshinaga, N.; Ushioda, K.; Ogata, S. Comparison of the dislocation density in martensitic steels evaluated by some X-ray diffraction methods. ISIJ Inter. 2010, 50(6), 875-882.
|
- The author claimed the EDX data indicates that the contamination from the milling tools is lower (1.5 at.%). How is the error range of EDX measurement? Is this the Fe contamination? It is hard to convince the readers that the contamination from milling tool is so low, especially for the powders milled by SPEX shaker ball mill after 80 hours. Although the experiments were performed in inert Ar atmosphere, the oxygen accumulation from milling atmosphere can’t be neglected for 80 h as-milled powders. The oxygen content of as-milled powders should report.
Answer: It is a good remark. We add information about the oxygen contamination.
Oxygen is also found, probably favored by high surface area of the particles in contact with air after milling process. Values are lower than 2.5 ± 0.5 at.%.
We also provide an error range in the EDS measurements. It is known that EDS can be considered as a semi-quantitative technique.
- The authors present detailed analysis about the transfer of energy in both milling devices. For shaker ball mill, the calculation of kinetic energy/mass powder ratio is based on the frequency of 14.6Hz = 876 r.p.m, which is provided by the manufacturer. Because this is the first step of calculation, the accuracy of this value is very important. Therefore, the author should report the detailed method or procedure that the manufacturer used to obtain this value.
Answer:
I cannot assure which method use the manufacturer to obtain the frequency. Probably, it is based on direct observation methods. Commercial devices are closed for security. Likewise, the provided value has been used in the energy transfer models of these alloys as indicated in the literature, as some references of this manuscript. New devices (our device have is more than 20 years old) can work at 1080 r.p.m. We provide the link to the technical information of this device.
8000M MIXER/MILL (spexsampleprep.com)
Reviewer 4 Report
Dear Authors,
I have read your paper "Fe-X-B-Cu (X= Nb, NiZr) alloys produced by mechanical alloying: influence of milling device" carefully.
This paper describes the effect of milling device on the microstructural evolution of the Fe-Nb-B-Cu, and Fe-NiZr-B-Cu alloys .
Explanations are clear and the paper is easy to read.
But the materials and methods are not properly described, so that other research groups may not reproduce them.
The paper is interesting. However, it requires few corrections.
1. Please, add the more information about application for this alloys.
2. Please, modify section 2. Materials and Methods. It would be more useful for readers if you report about size of the jars and balls in this section.
3. What was the proportion between jars or balls and mix of the powders?
4. Please, add information about Spex 800 shaker mill. I do not find information about this shaker mill (https://www.spexsampleprep.com/search.aspx?search=shaker+mill).
The paper can be accepted for publication only after major improvements.
Author Response
Reviewer 4:
Explanations are clear and the paper is easy to read.
But the materials and methods are not properly described, so that other research groups may not reproduce them.
The paper is interesting. However, it requires few corrections.
- Please, add the more information about application for this alloys.
Answer:
We add more information about application in the introduction section.
There are soft magnetic offering reduced core losses over a wide range of applied frequencies. These alloys are an alternative for industrial (automotive, green energy) applications: high precision energy meters, absorber cores for suppression of motor bearing currents, high frequency current transformers, push-pull transformers for power transistors, current sensors [3,4,6]. Due to magnetocaloric effect of the ferromagnetic to paramagnetic transition, these materials have been also of interest for magnetic refrigeration [7].
We also add a new reference
- Alleg, S.; Chabi, T.; Bensebaa, N.; Saurina, J.; Escoda, L.; Hlil, E.K.; Suñol, J.J. Investigation on the critical behavior, magnetocaloric effect and hyperfine structure in the Fe72Nb8B20 Materials 2020, 13 (20), 4476.
Furthermore, there are nanoperm alloys in the market.
PowerPoint Presentation (mbw.md)
- Please, modify section 2. Materials and Methods. It would be more useful for readers if you report about size of the jars and balls in this section.
Answer:
We modify this section. We add information about jars and balls in this section.
The milling (10 g of powders) was performed in both devices with Cr-Ni steel jars (45 ml capacity) and balls (12 mm diameter) for 5, 20 and 80 hours. The initial filling factor was close to one half. In SPEX the frequency is 14.6Hz = 876 r.p.m. (data provided by the manufacturer), whereas in the P7 the selected frequency of rotation of the platform, Ω, and jars, ω, is the same, 600 r.p.m. The R radius of the platform (measured from the geometric center of the jar position to the center of the platform) of the P7 is R = 7 cm and the internal radius of the jars r = 1.7 cm. The internal radius of the SPEX jar is 2.1 cm. The ball radius Rb is 0.6 cm. The ball to powder weight ratio, BPR, used in both devices has been the same: 5.
- What was the proportion between jars or balls and mix of the powders?
Answer:
We also add this information in the Materials and method section.
The ball to powder weight ratio, BPR, used in both devices has been the same: 5.
- Please, add information about Spex 800 shaker mill. I do not find information about this shaker mill (https://www.spexsampleprep.com/search.aspx?search=shaker+mill).
Answer:
The technical information of this shaker can be found in the following website.
8000M MIXER/MILL (spexsampleprep.com)
Furthermore, additional information about its movement is now given in the manuscript.
In the SPEX 8000 shaker mill, the jar containing powders is agitated at a high frequency in a complex cycle that involves motion in three orthogonal directions (combining back-and-forth swings with short lateral movements, each end of the vial describing a figure like an eight).
Round 2
Reviewer 2 Report
The revised version looks fine. It can be accepted for publications.
Author Response
The comment of the reviewer was:
"The revised version looks fine. It can be accepted for publications."
We agree the referee comments in both rounds.
Reviewer 3 Report
There are several comments that authors didn’t make clear response.
- The error range of EDX measurement: I didn’t find any error range in the revised manuscript which authors claimed they have provided. The authors agree that “EDS can be considered as a semi-quantitative technique”. Therefore, the values of contamination from the milling tools and oxygen must reconsider. Especially, these data will interference the activation energy as calculated from DSC curves.
- Measurement of dislocation density from TEM results: The authors said no TEM in their University, but I believe they can perform the TEM analysis in other academic institutions. They also agree that “TEM values are considered as more accurate due to direct observation.”. Therefore, measurement of dislocation density from TEM results must be provided.
- Detailed method or procedure to get frequency of 14.6Hz = 876 r.p.m for SPEX ball mill: The most important part of this manuscript is the analysis of transfer of kinetic energy in both milling devices, therefore all the calculation based on the selected model or data must be solid support by published literatures or rigorous analysis. Unfortunately, the authors didn’t provide any statement about this issue. Authors also said they didn’t find the direct comparison of SPEX and P7 devices. Actually, several reports about this topic have been published (for example, Indian Journal of Engineering & Materials Sciences, Vol. 22, October 2015, pp. 521-526.). It is necessary to survey these papers and selected the data or equation which are most closed to the milling parameters used in present study, and used them to proceed calculation. In addition, the energy used for the SPEX: (Ec/m) = 1.80 J/Kg, which quoted from Ref. [29] is not appropriate. The model described in reference 29 is used for planetary ball mill, not SPEX ball mill.
- Frequency or cycle for SPEX ball mill: The frequency of SPEX ball mill used in this study is 16Hz, which equals to 876 r.p.m. Authors said the new devices can work at 1080 r.p.m, and their 20 years old device is 876 r.p.m. For new device, from specifications of company, it is 1725 RPM @ 60Hz, 1425 RPM @ 50Hz (for motor) and 1060 cycles/minute (115V) or 875 cycles/minute (230V) (for clamp speed). What is exact frequency or r.p.m used in this study? Or it should be cycle, not frequency!!
According to the above comments, the work clearly does not meet the requirements of Metals. I therefore recommend rejecting this paper.
Author Response
We agree the comments. We modify the manuscript taking into account the suggested model for energy transfer. Furthermore, we modify several typographic mistakes.
There are several comments that authors didn’t make clear response.
- The error range of EDX measurement: I didn’t find any error range in the revised manuscript which authors claimed they have provided. The authors agree that “EDS can be considered as a semi-quantitative technique”. Therefore, the values of contamination from the milling tools and oxygen must reconsider. Especially, these data will interference the activation energy as calculated from DSC curves.
Answer:
We add the error range in the manuscript.
. The measurements indicates that the contamination from the milling tools is lower than 1.5 ± 0.5 at.%; typical results coherent with those previously found [10, 15]. Oxygen is also found, probably favored by high surface area of the particles in contact with air after milling process. Values are lower than 2.5 ± 0.5 at.%.
Likewise, EDS as well other techniques for compositional analysis as inductive coupled plasma (ICP) are considered as semi-quantitative because results are based on the calibration with standards. There are several hundred of articles with EDS microanalysis of mechanically alloyed powders are
Regarding DSC analysis, we add a comment about oxygen content.
The activation energies are higher in samples milled in the shaker mill, probably favored by different milling energy transfer and/or high content of oxygen (~ 0.5-0.8 at.%) in powders milled in shaker mill. Likewise,
The activation energy for the formation of oxides is higher than typical values associated to crystalline growth.
- Measurement of dislocation density from TEM results: The authors said no TEM in their University, but I believe they can perform the TEM analysis in other academic institutions. They also agree that “TEM values are considered as more accurate due to direct observation.”. Therefore, measurement of dislocation density from TEM results must be provided.
Answer:
TEM analysis has not been performed. We modify our comment. Sometimes there are discrepancies between XRD and TEM results, not always.
It should be remarked than XRD methods sometimes can provide higher values of the dislocations density than transmission electron microscopy (TEM) analysis [16]. TEM values are considered as more accurate due to direct local observation. Nevertheless, milling process favors inhomogeneity in the crystallographic defects.
Likewise, TEM analysis should be always performed very carefully. MA favors the inhomogeneity in the distribution of the crystallographic defects.
- Detailed method or procedure to get frequency of 14.6Hz = 876 r.p.m for SPEX ball mill: The most important part of this manuscript is the analysis of transfer of kinetic energy in both milling devices, therefore all the calculation based on the selected model or data must be solid support by published literatures or rigorous analysis. Unfortunately, the authors didn’t provide any statement about this issue. Authors also said they didn’t find the direct comparison of SPEX and P7 devices. Actually, several reports about this topic have been published (for example, Indian Journal of Engineering & Materials Sciences, Vol. 22, October 2015, pp. 521-526.). It is necessary to survey these papers and selected the data or equation which are most closed to the milling parameters used in present study, and used them to proceed calculation. In addition, the energy used for the SPEX: (Ec/m) = 1.80 J/Kg, which quoted from Ref. [29] is not appropriate. The model described in reference 29 is used for planetary ball mill, not SPEX ball mill.
Answer:
We modify the manuscript to introduce the model described in the reference suggested by the referee, and delete the energy transfer initially calculated. Likewise, we adapt and maintain the discussion about total time and the equivalent time because there are complementary. Likewise, deleted 1.8 J/kg was given in reference 19 (29 was wrong).
…. Furthermore, real processes have a distribution of energies involved in collisions due to a distribution of ball velocities in the shocks [28]. Some of the studies carried out take into account the direct comparison of shaker Spex and planetary mills [19,29].
First, for the comparison between both devices we apply the method described in ref. [29]. In order to evaluate the total energy transferred to the powder during milling is necessary to know the ball velocity. In the Spex device the ball velocity given in ref [29] is v = 2.5 m/s. To have an equivalent value in the P7, it has been chosen to determine the speed, v, of ball impact by applying the formula [30].
v2 = (RΩ)2 + (r-rb )2 ω2 (1+(2ω/Ω), (3)
As introduced in the Materials and Methods section, in SPEX the cycles are 876 r.p.m, whereas in the P7 the selected number of cycles (jar, platform) is ω = Ω = 600 r.p.m. The P7 radius of the platform R = 7 cm, the ball radius Rb is 0.5 cm for P7; and the internal radius of the jar r = 1.7 cm. The calculated velocity is v = 0.79 m/s. Obviously, these values should be considered for devices comparison, real energy transfer have a distribution of speeds. Other models provide different velocity, as an example, the expression of reference [31] provides a value of v=2.04 m/s for P7.
Regarding the kinetic energy, Ec, transferred by a ball in the planetary mill, can be calculated directly from the velocity. The calculated value is 0.002 J. The equivalent calculation in the shaker was calculated in ref. [29] and the kinetic energy is 0.026 J.
The normalized (by unit mass of powder) total energy (E/m) transferred at a given milling time, t, was calculated by taking into account the following expression [32]:
E/m = (n Ec t / m) (4)
Were n is the balls number. As shown in table 7, the calculated values for 80 h of milling are (E/m)SPEX= 5193 J/g and (E/m)P7= 3752 J/g. Thus, milling is more energetic in the Spex device.
Table 7. Ball velocity, kinetic energy and total energy of Spex and P7.
|
Mill |
Ball velocity m/s |
Kinetic energy J |
(E/m) J/g |
|
P7 |
0.79 |
0.002 |
3752 |
|
SPEX |
2.5 |
0.026 |
5193 |
The applied model considers that the frequency of impacts (events frequency) is equivalent in both devices. This factor is
Furthermore, we add four references:
Concas, A.; Pisu, M.; Lai, N.; Cao, G. Modelling of comminution in processes in Spex Mixer/Mill. Chem. Eng. Sci. 2006, 61, 3746-3760.
Dastanpoor, E.; Enayati, M.H. Effect of milling intensity on mechanical alloying of Cu-Zr-Al system. Ind. J. Eng. Mater. Sci. 2015, 22, 521-526.
Gheisari, Kh.; Oh, J.T.; Javadpour, S.; Ghaffari, M. J. The effect of milling speed on the structural properties of mechanically alloyed Fe-45% Ni powders. J. Alloys & Comp. 2009, 472, 416-420.
Singh, Sh.; Godkhindi; M.M.; Krishmarao, R.V.; Murty, B.S. Effect of milling energy on mechanical activation of (Mo+Si3N4) powders during the synthesis of Si3N4-MoSi2in situ composites. J. Euro. Ceram. Soc. 2009, 29, 2069-2077.
- Frequency or cycle for SPEX ball mill: The frequency of SPEX ball mill used in this study is 16Hz, which equals to 876 r.p.m. Authors said the new devices can work at 1080 r.p.m, and their 20 years old device is 876 r.p.m. For new device, from specifications of company, it is 1725 RPM @ 60Hz, 1425 RPM @ 50Hz (for motor) and 1060 cycles/minute (115V) or 875 cycles/minute (230V) (for clamp speed). What is exact frequency or r.p.m used in this study? Or it should be cycle, not frequency!!
Answer: We agree the information given by the referee. We introduce this parameter as cycles (in the literature terms as frequency of rotation or rotational speed. Our device works at 875 r.p.m. We update the information.
. In SPEX, the information by the provider is that the number of cycles (rotational speed or frequency of rotation) is 875 r.p.m., whereas in the P7 the selected cycles of the platform, Ω, and jars, ω, is the same, 600 r.p.m.
As introduced in the Materials and Methods section, in SPEX the cycles are 875 r.p.m, whereas in the P7 the selected number of cycles (jar, platform) is ω = Ω = 600 r.p.m. The P7 radius of the platform R = 7 cm, the ball radius rb is 0.5 cm for P7; and the internal radius of the jar r = 1.7 cm.
Author Response File: Author Response.pdf
Reviewer 4 Report
Dear Authors,
I have read your modified paper "Fe-X-B-Cu (X= Nb, NiZr) alloys produced by mechanical alloying: influence of milling device" carefully.
The materials and methods are properly described, so that other research groups may reproduce them. Explanations are clear and the paper is easy to read.
I can recommend the Editor to accept this revised manuscript to be published in Metals.
Author Response
The comment of the reviewer is:
"
Dear Authors,
I have read your modified paper "Fe-X-B-Cu (X= Nb, NiZr) alloys produced by mechanical alloying: influence of milling device" carefully.
The materials and methods are properly described, so that other research groups may reproduce them. Explanations are clear and the paper is easy to read.
I can recommend the Editor to accept this revised manuscript to be published in Metals."
We agree the comments of the reviewer in both rounds
