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Dear Colleagues,

The hottest parts of aero-engines, power generation gas turbines, or some industrial plants (such as glass forming) require superalloys for their high strength and ductility at high temperatures and their resistance against chemical deterioration when they are exposed to complex mixtures of oxidant gases or aggressive molten substances. From the first superalloys used during WWII to the ones now available for applications that are very much demanding of thermal, mechanical, and chemical properties at elevated temperatures, many innovations and developments have been achieved. Performances have significantly increased, allowing for higher energy efficiency and longer sustainability of components. Currently, new improvements are being realized on classical superalloys and promising methods in the field of novel composition principles as well as fabrication techniques are emerging.

Accordingly, we invite metallurgist researchers studying superalloys to share their recent findings in this Special Issue entitled “Recent Advances in Metallurgy and Properties of Superalloys”. The submitted contributions may include but are not limited to the following possible topics:

New complex chemical compositions and microstructures for superalloys;
Advances in the development and improvements in the properties of alloys based on highly refractory metals;
Microstructures and properties of superalloys fabricated by additive manufacturing;
Advances in the engineering of reinforcement of superalloys and emerging new mechanical strengthening methods;
Improvements in resistance against isothermal or cyclic oxidation or corrosion;
Understanding of the oxidation and corrosion phenomena in complex aggressive hot gaseous and molten milieus;
New coatings for more efficiently protecting superalloys.

Dr. Berthod Patrice
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Related Special Issue

Published Papers (3 papers)

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Research

13 pages, 5401 KiB

Open AccessArticle

Effect of Co and Cr on the Stability of Strengthening Phases in Nickelbase Superalloys

by Martin Bäker and Joachim Rösler

Crystals 2022, 12(8), 1084; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12081084 - 02 Aug 2022

Cited by 2 | Viewed by 1286

Abstract

Nickel-base superalloys such as VDM 780 may possess a high content of Cr and Co. This influences solution energies of phase-forming elements such as Al and Ta (

γ^{'}

-phase), Nb (

γ^{″}

- and

δ

-phase), and Ti (

η

[...] Read more.

Nickel-base superalloys such as VDM 780 may possess a high content of Cr and Co. This influences solution energies of phase-forming elements such as Al and Ta (

γ^{'}

-phase), Nb (

γ^{″}

- and

δ

-phase), and Ti (

η

-phase). We perform density functional theory studies of a nickel matrix at 0 K with high concentrations of either Co and Cr and calculate the influence of these elements on solution energies. In the case of Co, the solution energy can be predicted well by the nearest-neighbor interaction in the Co-rich matrix. For Cr, the effect is more complicated because Cr has a larger ionic radius and changes the magnetic state of the material. The effect of a Cr-rich matrix on the energy of Co is dominated by magnetic effects and interactions with the other elements by elastic deformation of the lattice. A high content of Co or Cr will thus increase the solvus temperature of the strengthening phase in nickel-base superalloys, in agreement with the literature and thermodynamic calculations. Full article

(This article belongs to the Special Issue Recent Advances in Metallurgy and Properties of Superalloys (Volume II))

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Figure 1

17 pages, 3666 KiB

Open AccessArticle

Creep and Oxidation Behaviors of 25 wt.% Cr–Containing Nickel-Based Alloys Reinforced by ZrC Carbides

by Patrice Berthod and Safa Tlili

Crystals 2022, 12(3), 416; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12030416 - 17 Mar 2022

Viewed by 1599

Abstract

Three alloys based on nickel, rich in chromium due to their oxidation resistance at high temperature and containing ZrC carbides for their mechanical reinforcing against creep, were elaborated by foundry. After control of their as-cast microstructures, these alloys were subjected at 1100 °C to flexural creep and to oxidation in air. Script-like ZrC carbides were obtained in the interdendritic spaces, forming a eutectic compound with a part of the matrix. One of the alloys additionally contained Cr₇C₃ eutectic carbides. By comparison with a Ni–Cr–C reference alloy with similar contents in Cr and C, the three alloys demonstrated a much better creep resistance for the same conditions of stress and temperature. However, their oxidation rates were much greater than for the reference alloy. In contrast with the chromia-forming reference alloy, several kinds of oxides formed in the case of the three alloys, as NiCr₂O₄ spinel and oxides involving zirconium. A significant inward interdendritic oxidation progression was noticed for the three studied alloys. To benefit from the interesting creep resistance of these alloys for long sustainability in service, it appears necessary to significantly improve their oxidation behavior. Full article

(This article belongs to the Special Issue Recent Advances in Metallurgy and Properties of Superalloys (Volume II))

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Figure 1

15 pages, 4380 KiB

Open AccessArticle

Oxidation and Microstructural Behaviors at 1200 °C of 32.5 wt.% Cr–Containing Co–Based Alloys Strengthened by HfC Carbides

by Patrice Berthod

Crystals 2022, 12(3), 361; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12030361 - 08 Mar 2022

Cited by 1 | Viewed by 1508

Abstract

Two alloys based on cobalt, designed to be reinforced by HfC and containing chromium with content beyond 30 wt.%, were produced by casting. They were subjected to a 46 h–long isothermal exposure at 1200 °C in synthetic air with thermogravimetric monitoring of the oxidation progress. In the as–cast state, the two alloys contain high quantities of script–like shaped HfC carbides. Both of them demonstrated a much better behavior than previous similar alloys containing only 25 wt.% Cr. After 46 h at 1200 °C, the morphology of the carbides had almost not evolved. The control of the creep behavior at 1200 °C showed that these oxidation–resistant alloys are, additionally, as creep–resistant as the 25 wt.% Cr containing previous alloys. Full article

(This article belongs to the Special Issue Recent Advances in Metallurgy and Properties of Superalloys (Volume II))

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