Dry Sliding Wear Features of an Al-20Sn-5Zn Alloy Affected by Microstructural Length Scales
, Clarissa Cruz 2, Tamires Botelho 3, Adrina Silva 3, Luiz Casteletti 4, Amauri Garcia 1,* and Noé Cheung 1
Round 1
Reviewer 1 Report
Considering a paucity of studies that associate the solidification microstructure with the wear resistance of Al-Sn-Zn alloys which are attractive options for use as wear-resistant materials, this study aims at investigating the wear behavior of an Al-20Sn-5Zn [wt.%] alloy produced by a directional solidification technique. The microstructure, chemical composition, wear behavior, etc. are analyzed and equations are proposed to represent a possible range of wear volume and wear coefficient. The paper can be considered for acceptance if the following minor questions could be addressed seriously.
(1) Ten Al-20Sn-5Zn [wt.%] alloy samples with different thermal histories during solidification were produced and characterized. How the ten samples with different thermal histories work in the study?
(2) In lines 212 through 225, Figure 4(a) and (b) are mentioned in the text, but not seen in Figure 4. Besides, the evolution of the grains and their causes are analyzed here, although the macro/microstructural features along the solidification direction could be annotated in more detail in Figure 4.
(3) In section 3.3, only the morphological characteristics of some samples after wear in the test are compared. Due to the difference in macroscopic and microscopic morphology of the samples along the solidification direction, it might be useful to additionally compare the 5 and 25 mm samples, especially since they are both considered to have a more intense solidification kinetic in the same region in section 2.3.
(4) In Figure 10, adhesive, abrasive and oxidative wear that mentioned at line 298 could be marked out.
（5）At line 338, ‘Only two SD … in common for all studies’. It could be explained in more detail about all studies.
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Reviewer 2 Report
This is a very nice piece of materials science. Interesting results. Discussion could be strengthen if Authors address what they themselves indicated interesting finding i.e. reverse dependence of wear resistance on hardness. Contrast of SEM images should be improved, particularly shown in Fig.11
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Reviewer 3 Report
Reviewed study aims at investigating the influence of the microstructure length scale on the wear behavior of an Al-20Sn-5Zn [wt.%] alloy. In work first samples with different thermal histories during solidification were produced using a directional solidification technique. Then, samples with quite distinct parametric microstructural features were subjected to ball-cratering tests. Hardness tests were conducted as well.
The paper contains interesting research material that contains new elements in relation to the current state of knowledge. The greatest achievements of the authors include:
Mathematical relations permitting to describe the coarsening of dendritic arms of an Al-20Sn-5Zn [wt%] alloy during transient solidification.
Determining the dependencies allowing to determine the wear features of the Al-20Sn-5Zn [wt.%] alloy, with focus on the microstructure length scale.
The development Multiple Linear Regression fits for the prediction of the wear features from microstructural parameters.
The work structure is correct. The introduction contains an analysis of the current state of knowledge, the Materials and Methods section, a description of research methods and experimental plans, and methods of sample preparation. Conclusions are ending. It should be pointed out here that the results and discussion section should be clearly indicated in the paper, as there is no clear transition from the Materials and Methods section to the description of the research results. Please also expand the conclusions section, which is modest.
The publication may be published after applying the indicated corrections.
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Reviewer 4 Report
The paper could be improved by addressing the following comments,
1. References 1 and 2 are irrelevant citations.
2. XRD and EDS mapping reveals only single elements. What about the formation of Phases (any binary or ternary). How the Phases influence wear behavior of alloy.
3. May reduce the number of Figures in Fig 8.
4. Conclusion should be rewritten, as it contains only results.
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