Manipulating Nucleation Potency of Substrates by Interfacial Segregation: An Overview
, Teruo Hashimoto 2, Xiaorong Zhou 2, Quentin M. Ramasse 3 and Zhongyun Fan 1
Round 1
Reviewer 1 Report
The authors presented a huge overview of their and others works on the topic of interfacial segregation on metal substrates. The material is properly structured and illustrated, both experimental (HRTEM) and modeling (AIMD) aspects are covered. Zr- and Si- poisoning phenomena are described at the state-of-the-art level. The manuscript can be published as is if does not exceeds the size limit for Metals journal. I have two minor comments:
1. Material of such a size absolutely needs a table of contents for convenient navigation.
2. "Gibb's" in the title of 2.1 is incorrect for Josiah Willard Gibbs surname.
Author Response
- Material of such a size absolutely needs a table of contents for convenient navigation.
Reply: We agree with the idea from the referee. A table of contents is added accordingly.
- "Gibb's" in the title of 2.1 is incorrect for Josiah Willard Gibbs surname.
Reply: Apology for the error made on the name of the great scientist. It should have never happened.
Reviewer 2 Report
I believe that your review article is very valuable and will attract interest from both researchers and foundry industry professionals involved in making Al or Mg matrix alloy castings.
I propose to make some corrections of an editorial nature.
1. Consider moving some of the descriptions of the full wording of the names of the research methods used from Section 2.3.2 to the last paragraph of the Introduction, where these abbreviations first appear.
2. Lines 208-210 and 774-777 use a different font size than the rest of the text.
3. Correct a typo in the name of the vertical axis in Fig. 13b "Density".
4. Two dots instead of one appear at the end of the captions under several figures.
5. It doesn't hurt to describe the method and reagent for metallographic etching for microphotography in Figure 15.
6. I suggest reorganizing the arrangement of materials so that figures and their captions fit on the same page (see Figure 4 in the materials submitted for review) and that figures appear after they are listed in the text.
Author Response
I believe that your review article is very valuable and will attract interest from both researchers and foundry industry professionals involved in making Al or Mg matrix alloy castings.
I propose to make some corrections of an editorial nature.
- Consider moving some of the descriptions of the full wording of the names of the research methods used from Section 2.3.2 to the last paragraph of the Introduction, where these abbreviations first appear.
Reply: Agree. We have modified them.
- Lines 208-210 and 774-777 use a different font size than the rest of the text.
Reply: they are the same font size 10.
- Correct a typo in the name of the vertical axis in Fig. 13b "Density".
Reply: It is corrected.
- Two dots instead of one appear at the end of the captions under several figures.
Reply: They are corrected in Figs. 12, 14. 17, 18, 23.
- It doesn't hurt to describe the method and reagent for metallographic etching for microphotography in Figure 15.
Reply: We provides the description of the sample preparation procedure in section 2.3.4. The 2nd paragraph is modified as: “Specimens for quantitative metallography of the solidified Al- and Mg- alloy TP-1 ingots were prepared following the standard grinding and polishing procedures. The preparation procedure of the Al alloy samples for optical microscopy is that, after grind-ing by SiC abrasive papers and final polishing by SiO2 suspension, the specimens were anodized in Barker’s reagent (5 ml HBF4 + 200 ml distilled water) under a voltage of 15-20 V for 1-2 min. Examination of grain structure and quantification of grain size were carried out at in both the transverse and longitudinal sections of the solidified TP1 ingots under polarized light using a Zeiss optical microscope fitted with the Axio Vision 4.3 image analysis system.
- I suggest reorganizing the arrangement of materials so that figures and their captions fit on the same page (see Figure 4 in the materials submitted for review) and that figures appear after they are listed in the text.
Reply: All figure captions have been made sure to appear in the same page of the corresponding figures.
Reviewer 3 Report
This is an excellent paper it can be a good contribution for the journal Metals, nucleation and growth is a very important topic in metals and in materials science; but I found some details as I comment next:
a) There are some empty lines between 304 to 312 on page 7.
b) 0n line 642 there is (..) on page 20.
c) On line 840 there is a blank space please verify on page 27.
d) A personal question on figure (15b) these are grains or dendrites inside grains..?
e) Between some lines as an example inside lines (364-371) (677-691) 1033-1043) o.k. I am agreeing with the explanations but maybe redaction can be improved for a better understanding of readers if you can improve excellent.
After check this I am sure the paper will be ready for publication.
Congratulations it is a very nice work.
Author Response
This is an excellent paper it can be a good contribution for the journal Metals, nucleation and growth is a very important topic in metals and in materials science; but I found some details as I comment next:
- a) There are some empty lines between 304 to 312 on page 7.
Reply: The empty lines are filled with texts.
- b) 0n line 642 there is (..) on page 20.
Reply: The typo in the figure caption is corrected, so are those similar typos.
- c) On line 840 there is a blank space please verify on page 27.
Reply: The typo in the figure caption is corrected.
- d) A personal question on figure (15b) these are grains or dendrites inside grains..?
Reply: The different colours indicate the individual grains, and there are well-developed dendrites inside the grains (only for Al-8.4Si).
- e) Between some lines as an example inside lines (364-371) (677-691) 1033-1043) o.k. I am agreeing with the explanations but maybe redaction can be improved for a better understanding of readers if you can improve excellent.
Reply: We have carefully gone through again the mentioned paragraphs as well as the whole manuscript. We think that the explanations are brief, concise and also clear enough. Readers who are interested in the details can access easily to the relevant publications given in the References list.
After check this I am sure the paper will be ready for publication.
Congratulations it is a very nice work.
Reviewer 4 Report
Review of the work: Manipulating Nucleation Potency of Substrates by Interfacial Segregation: An Overview
This document is a summary that shows the most recent works and advances focused on explaining the fundamental aspects associated with heterogeneous nucleation during solidification from the point of view of findings made when studying grain refining in Al-Base and Mg-Base alloys.
The results summarized in this work allow the reader to have a clear idea of the current state of the art and the frontier of knowledge regarding the mechanisms that apparently explain questions that had remained open for decades regarding the relationship between the nucleation potential and the presence of different solutes on the performance of different grain refiners.
In the document, the authors present sequentially and logically the concepts, strategies and tools they had to develop and use to generate practical and theoretical information that would allow analyzing the heterogeneous nucleation phenomena under study and proposing robust and convincing explanations.
The authors start from the proven and justified existence in terms of the reduction of interfacial energy, of the segregation of solutes towards the interfaces between the substrate and the metal that solidifies, to analyze the effect of this segregation on the effectiveness of a substrate to promote heterogeneous nucleation.
The document shows that the interaction between the solute segregated towards the interface and the substrate, with or without compounds previously present on its surface, defines whether there are substrate/metal interfacial modifications and changes in the nucleation potential of the substrate and its possible grain-refining ability.
The nucleation potential of a substrate depends on a) the lattice mismatch at the interface between the new solid phase and the substrate, b) the roughness at the atomic level of the substrate surface, and c) the chemical interaction between the solute segregated and species present at the interface between the substrate and the solidifying alloy.
Based on new paradigms explaining heterogeneous nucleation, the methodology developed analyzes aspects a) and b) through advanced electron microscopy, HAADF STEM simulations, and AIMD simulations. The chemical stability at the interface is established experimentally with evidence of the formation or disappearance of two-dimensional compounds present at the interface between the substrate and the solidifying alloy.
The authors show experimental evidence to document the above showing, for example, the segregation of Ti, Zr, and Si at Al/TiB2 interfaces and Y and La at Mg/MgO interfaces and detailed monitoring using advanced electron microscopy and mathematical simulations performed using experimental data, of the formation, substitution, or dissolution of two-dimensional intermetallic compounds present in the substrate/metal interface, which determines the nucleation potential of the substrate and, therefore, the effectiveness of the grain refiner.
Another relevant result for the reader to have an updated view of the options available to promote grain refining is the use of endogenous substrates to promote grain refining assisted by high shear stirring, as in the case of Mg-based alloys to disperse MgO oxide films and enable through significant nucleation undercooling the promotion of the so-called explosive grain initiation.
The research shown in this work and carried out to a large extent by the authors, constitutes a very relevant contribution that provides new paradigms to understand the importance of the interfacial segregation of solutes on the structure of the interface between the substrate and the alloy that solidifies and the subsequent nucleation through the epitaxial heterogeneous nucleation mechanism and its effect on grain refining.
Finally, the knowledge summarized in this work reveals the possibility, methodology, and available strategy to control the nucleation potential of the substrates with the ultimate goal of promoting conditions that allow better grain refining.
I consider the work carried out by the authors and summarized in this document excellent and exceptional. Its content allows dimensioning the vital contribution of the authors in understanding solidification in general and heterogeneous nucleation and grain refining in particular.
I think the work should be published in Metals in its current form for all of the above.
