Alloying Effects on the Stability of D022 γ”-Ni3M (M: Nb, Ta, V) Precipitates at Elevated Temperatures in Alloy 718 Type Ni-Based Alloys
Round 1
Reviewer 1 Report
In my opinion, a very interesting article with well-chosen experiments and interesting results. I have only a small remark: it seems to me that the density of precipitates g´´ in Fig. 2b is higher than in Fig. 2c.
Author Response
Thank you for your valuable comments. The density of gamma double prime precipitates in Fig. 2b is certainly higher than that of the precipitates in Fig. 2c due to different volume fraction (supersaturation) for the precipitates. We added micrographs in Fig. 4(e, f) and explanation in the corresponding part to show that a high density of gamma” precipitates is available also in V replaced alloys. The modified part is underlined and designated in red.
Reviewer 2 Report
Thanks, great job!
Author Response
Thank you for your encouraging comments. According to the other reviewer’s suggestions, we modified the manuscript. The modified part is underlined and designated in red.
Reviewer 3 Report
This work investigated the effects of alloying elements, M (M = Nb, Ta, and V), on the stability of D022 γ”-Ni3M precipitates at elevated temperatures. Improving the precipitate stability and the temperature capability of the Alloy 718 type Ni-based superalloys using a quaternary alloy using heat-treated diffusion-multiples and bulk samples with discrete chemical composition are also carried out. The detailed comments are as follows:
1. How can you determine the fine needle-like phase inside the grain in Fig2 is gamma double prime? As far as I know, the delta phase also presents needle shape under a specific heat treatment regime. This should be clarified here.
2. For the DSC result, there is only the transition peak of beta to gamma double prime, why the gamma double prime to delta peak is missing? This should be explained and discussed.
3. How is the mismatch calculated? Is it calculated from XRD results? Which peak was selected for calculation? Is deconvolution of peaks carried out? The calculation process needs to be presented here.
Author Response
Thank you for your valuable comments. We answer your comments individually below. You can find the modified part underlined and in red in the new manuscript.
- How can you determine the fine needle-like phase inside the grain in Fig2 is gamma double prime? As far as I know, the delta phase also presents needle shape under a specific heat treatment regime. This should be clarified here.
We discriminate the gamma precipitates from the delta phase in the micrographs by trace analysis based on the reported habit plane and crystallographic orientation relationship between the matrix and the precipitate phases. We added some explanation in the corresponding part and an example of trance analysis in Fig. 3(c).
- For the DSC result, there is only the transition peak of beta to gamma double prime, why the gamma double prime to delta peak is missing? This should be explained and discussed.
We have to admit that the original manuscript was misleading because the figure number was wrong. The indication from the HTXRD is that the beta phase transforms to the delta phase instead of the gamma double prime with heating. The figure numbering is corrected. We also modified the phase name inserted in the micrographs from β to δ(β), and added an explanation in figure captions, saying that “δ(β) denotes that the phase is of the β phase at the aging temperature but is transformed to the β phase during quenching to room temperature, as clarified in the section 3.2. and 3.3.” to make this point clear.
- How is the mismatch calculated? Is it calculated from XRD results? Which peak was selected for calculation? Is deconvolution of peaks carried out? The calculation process needs to be presented here.
The lattice parameters of the two phases were evaluated by selecting the XRD peaks for the γ phase: (111), (200), (220), (311), and (222) and the γ” peaks which do not overlap with the γ phase ones such as (110), (004), (202), (211), (114), (213), (204), (116), (224), (321), (314) without deconvolution of the peaks using the Cohen’s error function method. We added this explanation in the manuscript.
Round 2
Reviewer 3 Report
Well modified. Accept in the present form.
