Effect of the Surface Oxide Layer on Shape Memory Effect and Superelasticity of [011]-Oriented Ti-50.1Ni Single Crystals
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Abstract
1. A modest suggestion, the abstract is a refined overview of an excellent paper, the English in this section must be perfect and substantial. What is your contribution and what is the value of your work to other researchers?
Introduction
1. The introduction section should be logical and coherent. We want the narrative of the sentence to be coherent, and within this premise, we want the sentence to be as concise as possible. For example, line 49, 51, 54, 47, 50.
2. References cited are required to be accurate. It is possible to cite accepted theories from previous research, please check the accuracy of the cited references. See line 26.
3. All abbreviations in the text are required to be written in full at the first occurrence. For example, see the “R” in line 26.
Results
1. Figure 1, the indexing spot diffraction patterns is missing length unit ruler for inverted spaces.
2. Line 131, We require that the results can be seen directly in the figure. Otherwise, I'll consider your ‘Ni3Ti particles 15–20 nm in size are uniformly distributed over a thin foil’ statement to be vague.
3. Figure 2 and 3, Please pay more attention to the specifications of the pictures. Figure labels should be aligned, and figure layouts should highlight data changes.
Conclusions
1. Line 370, missing references.
I recommend a minor revision.
Author Response
Dear Reviewer,
The authors would like to thank for constructive comments. We have revised the paper in view of the comments made as detailed below.
Abstract
Comment 1: A modest suggestion, the abstract is a refined overview of an excellent paper, the English in this section must be perfect and substantial. What is your contribution and what is the value of your work to other researchers?
Response: In our opinion, the abstract corresponds to the content of the paper. The abstract indicates new observable facts and significant experimental results. Taking into account the comment, we have made corrections to the abstract.
Introduction
Comment 1: The introduction section should be logical and coherent. We want the narrative of the sentence to be coherent, and within this premise, we want the sentence to be as concise as possible. For example, line 49, 51, 54, 47, 50.
Response: Taking into account the comment, we have made corrections to the Introduction.
Comment 2: References cited are required to be accurate. It is possible to cite accepted theories from previous research, please check the accuracy of the cited references. See line 26.
Response: TiNi alloys in single- and polycrystalline state, depending on the composition and thermomechanical processing, as well as when they are obtained by various methods, including additive technologies, can experience two types of MT: one-stage B2-B19’MT and two-stage B2-R-B19’ MT. This is confirmed by the references [1-12] that we provide.
Comment 3: All abbreviations in the text are required to be written in full at the first occurrence. For example, see the “R” in line 26.
Response: The description for the abbreviations at the first mention was introduced.
Results
Comment 1: Figure 1, the indexing spot diffraction patterns is missing length unit ruler for inverted spaces.
Response: Ruler of length units for inverted spaces added.
Comment 2: Line 131, We require that the results can be seen directly in the figure. Otherwise, I'll consider your ‘Ni3Ti particles 15–20 nm in size are uniformly distributed over a thin foil’ statement to be vague.
Response: We agree with the reviewer's remark. We have corrected this sentence, since additional studies are needed to confirm the uniformity of the distribution of particles.
Comment 3: Figure 2 and 3, Please pay more attention to the specifications of the pictures. Figure labels should be aligned, and figure layouts should highlight data changes.
Response: Taking into account the comments, the figures 2 and 3 have been corrected.
Conclusions
Comment 1. Line 370, missing references.
Response: We have provided references.
All corrections in the paper were highlighted in red.
The authors thank the reviewer for her/his good job and constructive comments, and believe that the manuscript revised in the light of the recommendations properly addresses the concerns and is now suitable for publication in Metals.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors investigated the Effect of the Surface Oxide Layer on Shape Memory Effect and Superelasticity of [011]-oriented Ti-50.1Ni Single Crystals interesting study worth to be published after major revisions such as:
1) there is no data about the thickness of natural oxide film, TiO2, which forms on the surface of Ni Ti alloy when exposed to the air at room temperature ( it is around 10 nm) at 550oC is possible to get mixture of TiO2 and NixO oxides
2) the thickness of the oxide films is possible to evaluate using XPS (x-ray photoelectron spectroscopy) or TOF -SIMS -depth information is about 5 to 100 nm depends on ion sputtering, and definitively not SEM, the depth information of SEM-EDS is 1.5 to 3 microns
3) the method you mentioned as colour dependent thickness of TiO2 is not accurate enough
4) there is no analysis of oxide layer by surface analytical techniques, AES, XPS or ToF-SIMS
5) It is generally known that selective oxidation of NiTi occur.
The authors should read and add two references
A new route to biocompatible Nitinol based on a rapid treatment with H2/ O2 gaseous plasma. Applied Surface Science. [Print ed.]. April 2019, vol. 473, str. 976-984. ISSN 0169-4332. DOI: 10.1016/j.apsusc.2018.12.140.
Critical overview of Nitinol surfaces and their modifications for medical applications. Acta Biomater., 4 (2008), pp. 447-467, 10.1016/j.actbio.2008.01.013
Author Response
Dear Reviewer,
The authors would like to thank for constructive comments. We have revised the paper in view of the comments made as detailed below.
Comment 1: there is no data about the thickness of natural oxide film, TiO2, which forms on the surface of Ni Ti alloy when exposed to the air at room temperature ( it is around 10 nm) at 550oC is possible to get mixture of TiO2 and NixO oxides
Response: All samples after quenching before marforming and after annealing in helium gas at temperature of 440K for 0.5 h, before testing, were ground and polished to remove the effect of a natural oxide film on the study of functional and mechanical properties. This clarification was added to the experimental procedure.
Comment 2: the thickness of the oxide films is possible to evaluate using XPS (x-ray photoelectron spectroscopy) or TOF -SIMS -depth information is about 5 to 100 nm depends on ion sputtering, and definitively not SEM, the depth information of SEM-EDS is 1.5 to 3 microns
Response: We determined the thickness of the oxide layer and its chemical composition using SEM-EDS. The determination method is described in the section “Materials and Methods” in the second paragraph.
Comment 3: the method you mentioned as colour dependent thickness of TiO2 is not accurate enough
Response: We agree that this method is not accurate enough. But we use it as a qualitative confirmation of our values.
Comment 4: there is no analysis of oxide layer by surface analytical techniques, AES, XPS or ToF-SIMS.
Response: This was not the aim of the present paper. Our task was only to obtain an oxide layer during annealing in dry air and to study its effect on the shape memory effect and superelasticity and compare them with samples without an oxide layer.
Comment 5: It is generally known that selective oxidation of NiTi occur.
Response: We didn't focus on it. We investigated how a small surface oxide layer will generally affects the shape memory effect and superelasticity.
Comment 6: The authors should read and add two references: A new route to biocompatible Nitinol based on a rapid treatment with H2/ O2 gaseous plasma. Applied Surface Science. [Print ed.]. April 2019, vol. 473, str. 976-984. ISSN 0169-4332. DOI: 10.1016/j.apsusc.2018.12.140.
Critical overview of Nitinol surfaces and their modifications for medical applications. Acta Biomater., 4 (2008), pp. 447-467, 10.1016/j.actbio.2008.01.013
Response: References have been added.
All corrections in the paper were highlighted in red.
The authors thank the reviewer for her/his good job and constructive comments, and believe that the manuscript revised in the light of the recommendations properly addresses the concerns and is now suitable for publication in Metals.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors have supplemented the text of the manuscript, so it can be published
