Predicting the Quality of Grain Refiners from Electrical Resistance Measurements of Aluminum

Round 1

Reviewer 1 Report

The manuscript is devoted to aluminium alloys and the techniques to tune the grain size by Al3Ti and 12TiB2 particles. The occurence, size and chemical composition of the particles of the particles are confirmed by electron microscopy. DSC and electrical resistance measurements show the influence of the particles on the properties of aluminum alloys. There are couple of comments to be answered before publication in Metals journal.

1. In section two an old version of LabView package is mentioned, but neither reference nor a description is given to know the purpose of LabView-based program.

2. Absolute numbers in Fig. 4 and 5 are a bit confusing. Do they demonstrate the numbers of particles in single micrograph or multiple micrographs? Can on compare the numbers of Al3Ti and 12TiB2 particles?

3. What is the reason of multimodal (at least two peaks) distribution in Fig. 4 in contrast to Fig. 5?

Author Response

1. The purpose of use of LabView program was to measure ER. In the manuscript, the mention of this program was deleted as it is not so important.
2. The explanation of the results presented in Fig. 4 and 5 was complemented, and multiple micrographs were analysed.
3. Multimodal distribution is presented for four analysed grain refiners. Separately, Al3Ti and TiB2 particles are presented.

Reviewer 2 Report

The manuscript novelty is unclear and work looks as incompleted study. Follows recomendations may help to improve it. 

1. The difference in the ER may be the result of many factors, meanwhile the solute content is the most critical.  The discussion should be focused to this aspect, but not only to the phase morphology. The microstructures should be described before ER.

 2. To confirm phases XRD data are required. To confirm statistics, the EDS – maps for elemental distribution are helpful. In a present state, the results are speculative and measurements unclear. Histograms should be changed to distribution graphs, it is required for clarification.  

 

 3.  To confirm the theory of ER application to evaluate the effectiveness of inoculation process for grain refinement, for all studied master-alloys the influence on the grain structure, for example, of pure Al, should be presented.  Melting and casting should be done in the same conditions. The relation between Without this experiment, the presentation is weak.

 

 4. The basic knowledge about electrical conductivity are not required for a such long discussion. Well known that electrical  properties are very sensitive to the solid solution composition. Thus, follow part should be shortened.

 ` The electrical resistiv- 113 ity of alloys is higher than the resistivity of pure metal [17,18] because as the proportion 114 of impurity atoms in the alloy increases, e.g., B atoms in metal A, the scattering of electrons 115 increases and thus the resistivity increases. However, when the solubility of element B in 116 A decreases in the alloy and B is separated from A, forming phases, the electrical resistiv- 117 ity decreases in this case. This is due to less electron scattering when the B atoms are in 118 the form of phases in the metal than when they have dissolved in metal A.`

 

 5. Use only family names for reference in the texts, for example, Z. Fan  better to correct to Fan.

 

 6. Manuscript should be carefully proofread. ( for example, “Therefor” is “therefore” , etc)

 

Author Response

1. Microstructures are presented after ER measurements in order to provide the reasons for the differences in ER. The structure of the manuscript would be totally different, and the purpose of the presentation would not achieve the purpose. Some additional explanations regarding the solute content were complemented.
2. EDS-maps of elemental distributions were added, XRD was not done. I think that the phases were confirmed with the presented results.
3. The effectiveness of inoculants on Al99.7 aluminium alloy was added and additionally explained.
4. The part regarding electrical conductivity was shortened.
5. For references in the text only family names are used.
6. Manuscript was additionally proofread.

For all changes in the manuscript, we used Track changes.

Reviewer 3 Report

In the Introduction, you write that it is necessary to check for the best grain refiners. It would also be good to add at the beginning of the Materials and Methods section why these grain refiners were chosen.

In the same place, give a general plan of study, indicate the number of performed experimental studies to obtain each data. You wrote that grain refiners from 4 different manufacturers were used. It would be necessary to indicate to these manufacturers for which of the Al alloys the grain refiners were used.

Expand the description of the study methodology and structure this section.

In Figure 1, you have curves of different colors, but the legend doesn't explain why they have different colors. In the lower-left corner, apparently, an extra triangle. In the same figure and the description, phases with the content of Fe, and Si appear, but in the methodology and earlier you have nothing about the content of these elements and about the alloy for adding a refiner. This needs to be improved. It should be clear to the reader where and why the phases in the figures are taken.

In general, the article needs to be finalized so that it is more understandable to the reader and there are no new, previously undescribed things. Outline in the section Materials and Methods a general plan of study in the article and adhere to it.

In this article, it would be good to present photographs of the grain structure of the used alloy matrix, so that one can compare the impact of refiners on the matrix too. The average particle size and dispersion should be given in Figures 4 and 5.

It would be good to present a more in-depth analysis of the results in the article, obtain the values of the average indicators and bring them into a table, and expand the Conclusions by bringing the numerical values of these indicators.

Author Response

1. In the Materials and methods, the reason for choosing these grain refiners was added.
2. These grain refiners are used in wrought and cast aluminium alloys, which were complemented in the manuscript. The results for aluminium alloy Al99.7 were added.
3. The methodology was complemented with additional data.
4. Triangle in the Fig. 1 is the mark from Thermo-Calc. I would not like to delete it. The colours were incorporated into the manuscript. The influence of Fe and Si content on the grain refiners’ efficiency is explained in the Introduction part. Regarding the grain refiner’s composition, these elements form certain phases and influence in Al3Ti and TiB2 particles efficiency were added in Fig. 4 and 5.
5. General plan of the article was complemented in the Materials and Methods section.
6. Grain structure of Al99.7 grain refined with experimental grain refiners was added. Also, the average particle size.
7. Conclusions and in some parts of the results and discussion were complemented with the numerical values.

For all changes in the manuscript, we used Track changes.

Reviewer 4 Report

Could the authors consider the following comments in order to improve the manuscript?

Abstract:

In the second part of the abstract, the authors mentioned the grain refiner B, while it has not be introduced. The authors could be more specific of that particular grain refiner such as giving the composition of the master alloy and the value of the Ti/B ratio near 3.60 which seems to be (in this study) the optimal value.

Introduction:

page 3, line 117-118: the authors wrote : '... B separated from A, forming phases, the electrical resistivity decreases in this case.' For '...B separated from A...' the authors mean the concentration of B element in the alpha-phase constituant of the matrix riched in A element!

Page 4, line 140 : 'The labview 8.5 program was started... ' Is this part of the sentence necessary?

Table 3 : Could the authors add the scatter values for the average values of the area (based on the 10 measurements for the diameter) and the uncertaincy for the resistivity and conductivity?

Page 5, line 208 : '... was also evident in the melting and solidification enthalpy...' The solidification curves obtained from DSC are shown in Fig. 2 but not the melting during heating. If the authors do not show the DSC curves during the heatin they should mention : '... was also evident in the melting (not shown here) and solidification enthalpy...'. Also, the sentence should end with : '... which were the lowest for the grain refiners C and D. (assuming that the values obtained during heating and cooling were similar)'

Figure 2 : please mentioned that the DSC curves were obtained during cooling.

English:

page 2, line 77 : therefore (e at the end is missing)

page 3, line 119 : ... when they are dissolved in the metal A. (are instead of have and the article before metal).

Page 3, line 135-136: The sentence : 'For the electrical resistance measurements, the wires of the grain refiners were measured, with the radius measured at 10 points and the average radius calculated.' is not clear and could be reformulated.

page 5, line 191 : '... ratio that favors favorable conditions...' Please re-write this part of the sentence.

Page 5, line 193: the authors wrote : '... increases, indicating different shapes of Al3Ti particles, i.e., ...' This will be shown later. Thus the verb 'suggesting' would be better than 'indicating'...

Page 5, line 198: '... also decrease the electrical resistivity.' The article 'the' is missing.

Conclusion: line 276 : '... the grain refiner B prepared from Al-3Ti-1B with the Ti/B ratio egal to 3.60'

Author Response

1. In the abstract we explicitly wrote the grain refiner and certain properties of this grain refiner.
2. On page 3 the Introduction part was rewritten.
3. The LabWiew part was deleted.
4. Table 3 was complemented with measurement accuracy data.
5. Everything regarding the DSC melting was deleted. This occurred because, in the beginning, we had a purpose to present both results.
6. In Fig. 2 cooling is mentioned.
7. Page 2: Therefore is corrected.
8. Page 3: This part was rewritten.
9. Page 3, lines 135-136: Sentence was reformulated, and corrected.
10. Page 5, line 191: Sentence was rewritten.
11. Page 5, line 193: Indicating was replaced with suggesting.
12. Page 5, line 198: The was complemented.
13. Conclusions: Ratio 3.6 was added.

For all changes in the manuscript, we used Track changes.

Round 2

Reviewer 2 Report

The paper is impoved.

One new comment considers additional data. In figures authors presented the mean sizes of particles and grains. The error bars are requred to confirm a number of significant decimal places. The presented number seems statistically  incorrect.

Author Response

1. An average number of particles was calculated from up to 400 measures for Al3Ti particles and up to 65000 for TiB2 particles. If I also mark the error it would be weird to me, but if you insist, I can add it. The error would be bigger than the number itself.

Reviewer 3 Report

The authors have significantly improved the article. Thanks to the authors.

From small improvements, I would ask:

1. Enlarge the figure 2. It is small but contains a lot of data. It can simply be enlarged.

2. In tables, give dimensions separated by commas, and not by the "/" symbol.

Author Response

1. Fig. 2 is enlarged.
2. For dimensions separators comma is used.