Effects of Process Parameters on Microstructure and Mechanical Properties of Semi-Solid Al-7Si-0.5Mg Aluminum Alloy by Gas Induced Semi-Solid Process

Round 1

Reviewer 1 Report

In this work, the authors developed, employed and the effects of process parameters on microstructure and mechanical properties of semi-solid Al-7Si-0.5Mg aluminum alloy by the gas-induced semi-solid process. The paper proposes a new type of alloy that allows for improving the physical and mechanical properties, increasing the strength of the structure.

 

The paper is physically sound, technically solid, and can be accepted for publication after the following minor issues are addressed:

 

1. In line 100, describe the type and class of equipment.

2. Lines 160-165, please justify the image processing mechanism for grain size search.

3. Line 302, please prove the possibility of changing the microtexture depending on the change in the sampling method.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

The reviewed manuscript entitled “Effects of process parameters on microstructure and mechanical 2 properties of semi-solid Al-7Si-0.5Mg aluminum alloy by gas 3 induced semi-solid process” discusses the physical properties of aluminum alloy measured by various methods, i.e. DSC, metallographic microscope, tensile equipment, and preparation of slime/smudge/slurry and a die-casting procedure. I think the manuscript is well prepared, besides several errors, mistakes, etc., and can be interesting for the potential reader. Thus, I recommend this manuscript to publish in the Journal after minor amendments:

1.      Page 1 line 21: see point 13!

2.      Page 3 Table 1: Give the number of the Al content.

3.      Page 3 line 101: Concerning the mass of the sample used in the DSC measurements. In DSC measurements used masses of samples are about several mg (less than 7-10 mg). Why did the authors use the mass of 20 mg?

4.      Page 3 lines 99-103: Did the authors calibrate of the DSC equipment before their measurements? Please add information about a calibration (if any), a temperature control system, and the accuracy of temperature measurements.

5.      Page 4 Fig. 3(a): Add information, in the figure caption, about the regime (cooling/heating) and the pace of the measurements.

6.      Page 4 lines 135-143: Calculate the values of the thermodynamic functions as the change of enthalpy (and entropy) in the phase transitions. Both DSC thermograms – for heating and for cooling – have to be shown and compared.

7.      Page 4 line 142: The authors should explain why they chose a temperature of 590 degrees of C. On the other hand, without any explanation, they could choose any arbitrary value between 595.5 and 549.5 degrees of C!

8.      Page 4 Fig. 3(b): I think that the authors have to give an equation for how they calculate the solid phase fraction. It is a simple integration but the potential reader should be informed about the math calculations.

9.      Page 4 line 142: If the authors want to show a pace of the increase of the solid phase fraction, they can present a derivative of “the solid phase fraction %” with respect to temperature. Then the potential reader can easily see the range of temperatures of a fast or a slow increase of the solid phase fraction.

10.  Page 5 lines 144-148 and Fig. 4: (1) The used three curves have to be described in a figure legend (but there is no figure legend!) or in the figure caption. Without description Fig. 4 means nothing! (2) I think the scale of the vertical axis should be changed (i.e. from 585 to 615 degrees of C), so the potential reader can see anything from the presented figure! (3) I think within a time slot up to 150 s the calculated cooling rate is about that reported by the authors, i.e. 0.08 degrees of C per second. For a longer time, the cooling rate is just a little higher. Discuss this within the manuscript. (4) On the other hand, you should add an error for the calculated cooling rate during the holding time and the R coefficient.

11.  Page 5 Figs. 5(a)-(d): The authors should add some information about the structures shown in Figs. 5(a) – (d). Do they show the same areas of the material?

12.  Page 5 lines 154: Comparing results shown in Fig. 3(b) I could say, and the potential reader can also do such idea, something different. The potential reader can expect, looking at Fig. 3(b), that in 605 degrees of C there would be about 18%of the solid phase fraction, and in 590 degrees of C – about 70% of the solid phase fraction. But, on the other hand, based on the information given on page 10 lines 274-279, the differences in the solid phase fraction from the analysis of the DSC thermograms and Image J software can be different. Please explain this in several sentences. It is very crucial information!!!

13.  Page 6 lines 163-164: The authors wrote, citing: “(…) the semi-solid slurry increases from 163 ~0.67 to ~0.77(…)”. Really? Based on data presented in Fig. 6, with the increasing holding time (the temperature is lowering, by the way) the solid phase fraction is decreasing from 0.77 to 0.67. See the black triangles shown in Fig. 6!!!

14.  Page 6 Fig. 7: I think that the microstructure of the Al-7Si-0.5Mg aluminum alloy should be also shown at temperature 605 degrees of C. Then the potential reader can compare the microstructures with various added amounts of the Al-5Ti-B alloy (Figs. 7(a) – (d)) with the “virgin one”.

15.  Page 7 line 175: What does “the secondary grain” mean (for the authors)? Add the definition. Are the secondary grains a solid phase?

16.  Page 7 line 180: The average grain size decreases (!!!) from about 100 micrometers to about 68 micrometers!!! In the manuscript, there is “increased”.

 

17.  Misprints and errors found: (i) Page 4 line 128: There should be “P” instead of “D”; (ii) Page 6 Fig. 6, and page 7 Fig. 8: In the legends of Figs. 6 and 8 should be “Average grain size” instead of “Average particle size”; (iii) Page 6 Fig. 7: Add the temperature of the measurements shown there (i.e. 605 degrees of C).

Author Response

Please see the attachment

Author Response File: Author Response.pdf