Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
4.2
2.4
Journals
Crystals
Special Issues
Microstructure and Properties of Superalloys
share announcement

Microstructure and Properties of Superalloys

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystalline Metals and Alloys".

Deadline for manuscript submissions: closed (29 February 2024) | Viewed by 4773

Special Issue Editors

Dr. Pascal Thome

E-Mail Website
Guest Editor
Institute for Materials (IFM), Ruhr University Bochum, Universitätsstr. 150, 44801 Bochum, Germany
Interests: HR-EBSD; crystal mosaicity; quantitative microstructure characterization; microstructure informatics; artificial intelligence
Prof. Dr. Markus Stricker

E-Mail Website
Guest Editor
Interdisciplinary Centre for Advanced Materials Simulation, Ruhr University Bochum, Universitätsstraße 150, 44801 Bochum, Germany
Interests: dislocation-based plasticity; materials informatics; data fusion; microstructure characterization
Prof. Dr. Jan Frenzel

E-Mail Website
Guest Editor
Institute for Materials (IFM), Ruhr University Bochum, Universitätsstraße 150, 44801 Bochum, Germany
Interests: processing of engineering materials; shape memory alloys; superalloys; phase transformations; advanced microstructure characterization

Special Issue Information

Dear Colleagues,

Single crystal (SX) superalloys represent one of the most important classes of materials for high-temperature applications in both energy and aviation industries. Nickel- and Cobalt-base superalloys are the most common candidates for application in the hot parts of gas turbines, where they are often used as a polycrystalline material for disks or as single crystals for turbine blades. The microstructure, which is established by precisely controlled casting, solidification and heat treatment procedures, governs the mechanical performance at elevated temperatures. Manufacturing of SX superalloys traditionally involves casting processes such as Bridgman single crystal growth. Recently, alternative techniques such as fluidized carbon bed cooling and additive manufacturing have received significant attention as they lead to new perspectives in microstructure design. The effects of advanced processing techniques on mechanical properties are the subject of current research. Advances in quantitative microscopy and microstructural analysis have led to a better understanding of elementary microstructural evolution processes and high-temperature plasticity. Today, characterization methods such as high-resolution transmission electron microscopy and atom probe tomography allow a detailed investigation of dislocation mechanisms, the formation of planar defects and micro- and nanosegregations, and by employing high resolution electron back scatter diffraction, even very slight orientation irregularities can be analyzed across different length scales, to provide new insights into the multiscale microstructure of SX superalloys.

This Special Issue on “Microstructure and Properties of Superalloys” addresses recent research results on the relationship between manufacturing, microstructure, and properties, with a special focus on novel characterization methods.

Dr. Pascal Thome
Prof. Dr. Markus Stricker
Prof. Dr. Jan Frenzel
Guest Editors

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 2100 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.

Keywords

  • Ni-base superalloys
  • Co-base superalloys
  • microstructure
  • properties
  • advanced characterization

Benefits of Publishing in a Special Issue

  • Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
  • Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
  • Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
  • External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
  • e-Book format: Special Issues with more than 10 articles can be published as dedicated e-books, ensuring wide and rapid dissemination.

Further information on MDPI's Special Issue polices can be found here.

Published Papers (3 papers)

Download All Papers
Order results
Result details
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:

Research

20 pages, 12661 KiB  
Article
Optimization of the Mechanical and Corrosion Resistance of Alloy 625 through Aging Treatments
by Barbara Rivolta, Riccardo Gerosa, Davide Panzeri and Arsalan Nazim
Crystals 2024, 14(2), 139; https://doi.org/10.3390/cryst14020139 - 30 Jan 2024
Cited by 1 | Viewed by 1157
Abstract
In the as-annealed condition, the nickel-based Alloy 625 has excellent mechanical and corrosion properties compared to those of common stainless steels. This peculiarity enables its exploitation in several industrial fields at cryogenic and high temperatures and in the presence of severely corrosive atmospheres. [...] Read more.
In the as-annealed condition, the nickel-based Alloy 625 has excellent mechanical and corrosion properties compared to those of common stainless steels. This peculiarity enables its exploitation in several industrial fields at cryogenic and high temperatures and in the presence of severely corrosive atmospheres. However, in this alloy, when high-temperature plastic deformation processes and heat treatments are not carefully optimized, the occurrence of excessive grain coarsening can irremediably deteriorate the mechanical strength, possibly leading to incompatibility with the standard requirements. Therefore, this research work investigated the possibility of adopting single- and double-aging treatments aimed at improving such strength loss. Their optimization involved identifying the best compromise between the hardening effect and the loss in corrosion resistance induced by the simultaneous formation of intergranular chromium-rich carbides during aging. The investigation of the aging treatments was performed using hardness, tensile and intergranular corrosion tests considering different time–temperature combinations in a range from 621 °C to 732 °C. Double aging resulted in a considerable acceleration in the hardening response compared to single aging. However, even after its optimization in terms of both temperature and time, the intergranular corrosion resistance remained a critical aspect. Among all the tested conditions, only single aging at 621 °C for 72 h was acceptable in terms of both mechanical and corrosion properties. The influence of longer exposures will be investigated in a future study. Full article
(This article belongs to the Special Issue Microstructure and Properties of Superalloys)
►▼ Show Figures

Figure 1

10 pages, 2368 KiB  
Article
Influence of the γ′ Volume Fraction on the High-Temperature Strength of Single Crystalline Co–Al–W–Ta Superalloys
by Fei Xue, Andreas Bezold, Nicklas Volz, Andreas Kirchmayer, Christopher H. Zenk, Steffen Neumeier and Mathias Göken
Crystals 2023, 13(7), 1095; https://doi.org/10.3390/cryst13071095 - 13 Jul 2023
Cited by 1 | Viewed by 1455
Abstract
Understanding the influence of γ′ and secondary-phase fractions on the mechanical properties of superalloys is very important to optimize these high-strength materials. So far, this has not been systematically investigated for the novel class of Co-based superalloys. In this study, a Co–Al–W–Ta model [...] Read more.
Understanding the influence of γ′ and secondary-phase fractions on the mechanical properties of superalloys is very important to optimize these high-strength materials. So far, this has not been systematically investigated for the novel class of Co-based superalloys. In this study, a Co–Al–W–Ta model alloy series was designed with compositions of γ/γ′ on the tie-line and an increasing γ′ volume fraction of up to 70% after heat treatment at 900 °C, while a few alloys are unexpectedly out of γ/γ′ two-phase region with an additional secondary phase fraction of up to 15%. The high-temperature strength and creep properties were evaluated by compression tests up to 1050 °C and compressive creep experiments at 950 °C, respectively. At temperatures of up to 1050 °C, an increasing γ′ volume fraction consistently increased the yield strength, which was not dramatically changed by the presence of secondary phases. Significant work hardening was found in alloys with γ′ volume fractions of 65–70% during compression testing, but not in alloys with either a lower γ′ volume fraction (<50%) or a high fraction of secondary phases (~15%). Similar to the yield strength, the creep strength also increased continuously with the γ′ volume fraction, but was greatly reduced with an increasing fraction of secondary phases. The best creep performance at 950 °C and 200 MPa was found in the alloy with the highest γ′ volume fraction and no secondary phases. At higher creep stresses, rafting contributed significantly to the hardening and, again, the alloy with a high γ′ volume fraction and a small amount of secondary phases exhibited the highest strength. Full article
(This article belongs to the Special Issue Microstructure and Properties of Superalloys)
►▼ Show Figures

Figure 1

16 pages, 2829 KiB  
Article
Investigation of Hafnium Oxide Containing Zirconium in the Scaled Region on the Surface of As-Cast Nickel-Based Single Crystal Superalloy Turbine Blades
by KeeHyun Park and Paul Withey
Crystals 2023, 13(2), 277; https://doi.org/10.3390/cryst13020277 - 6 Feb 2023
Cited by 1 | Viewed by 1666
Abstract
Surface scale is usually formed in the aerofoil part of as-cast nickel-based single crystal turbine blades by the strong interaction between the mould wall and the melt, and the subsequent oxidation of the fresh metallic surface of the casting. For better understanding of [...] Read more.
Surface scale is usually formed in the aerofoil part of as-cast nickel-based single crystal turbine blades by the strong interaction between the mould wall and the melt, and the subsequent oxidation of the fresh metallic surface of the casting. For better understanding of the scaling, the scaled region was investigated, and an interesting region containing hafnium oxides and a rhenium-rich particle was found. Generally, a continuous aluminium oxide layer was detected on the outer surface of the base material and covered the surface of an unscaled region. In contrast, there was no oxide on the surface of a scaled region, but it was replaced by several tiny particles remaining locally on the outer surface of the base material. SEM-EDX and TEM-EDX point analysis of these particles indicated not only the existence of high amounts of hafnium, but also several particles such as hafnium oxide, aluminium oxide, and even tiny metallic particles. Most of all, STEM-EDX point analysis clearly detected zirconium in the hafnium oxide. Furthermore, a rhenium-rich particle was also detected towards the outer surface of the base material, which suggested that the surface of the scaled region might be exposed to high enough temperatures to allow the diffusion of heavy alloying elements. Based on the observation, the formation mechanism of hafnium oxide containing zirconium and its meaning was discussed. Full article
(This article belongs to the Special Issue Microstructure and Properties of Superalloys)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-3
Back to TopTop