Mechanical and Microstructural Characterization 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 (11 January 2024) | Viewed by 6331

Special Issue Editors

School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
Interests: superalloys; high-temperature titanium-based alloys; additive manufacturing; high-temperature deformation; high-temperature properties; microstructures
AECC Beijing Institute of Aeronautical Materials, Beijing 100094, China
Interests: superalloys; Ti; microstrcture characterization; deformation mechanisms; failure analysis

Special Issue Information

Dear Colleagues,

Superalloys are a group of nickel, iron–nickel and cobalt alloys used in aircraft turbine engines. These alloys have excellent heat-resistant properties and high stiffness, strength, toughness and dimensional stability at high temperatures. They also have good resistance to corrosion and oxidation at high temperatures. Titanium-based high-temperature alloys also have outstanding high-temperature strength and oxidation resistance, as well as much lower density. Currently, there are demands for high-performance high-temperature alloys via alloy design, microstructural control, emerging fabrication techniques, etc. This Special Issue focuses on advances in alloy development, microstructural control and processing, the characterization of microstructure and high-temperature behavior, and the physical metallurgy of high-temperature alloys, including superalloys and high-temperature titanium-based alloys. Potential topics may include, but are not limited to, the following:

  • New alloy design theory, new strengthening methods or mechanisms for high-temperature alloys;
  • Microstructural control and related high-temperature properties of high-temperature alloys;
  • Microstructural evolution and damage mechanisms of high-temperature alloys;
  • Microstructures and properties of additively manufactured high-temperature alloys;
  • Crystal growth and coatings of high-temperature alloys.

Prof. Dr. Chenglin Li
Dr. Nan Li
Guest Editors

Manuscript Submission Information

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Keywords

  • superalloy (Fe-, Ni-, Co-based alloys)
  • high-temperature Ti-based alloy
  • additive manufacturing
  • high-temperature properties
  • high-temperature deformation
  • fatigue
  • creep
  • oxidation
  • coating

Published Papers (4 papers)

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Research

22 pages, 7016 KiB  
Article
Automated Stereology and Uncertainty Quantification Considering Spherical Non-Penetrating Dispersions
by Magnus J. Anderson and Hector C. Basoalto
Crystals 2023, 13(3), 464; https://doi.org/10.3390/cryst13030464 - 08 Mar 2023
Cited by 2 | Viewed by 880
Abstract
Automated stereological methods are presented for approximating the 3D size distribution of unimodal or bimodal precipitate dispersions considering 2D and 1D measurements taken from polydisperse spherical non-penetrating particle dispersions. A method to quantify the uncertainty of the approximation as a function of the [...] Read more.
Automated stereological methods are presented for approximating the 3D size distribution of unimodal or bimodal precipitate dispersions considering 2D and 1D measurements taken from polydisperse spherical non-penetrating particle dispersions. A method to quantify the uncertainty of the approximation as a function of the number of sampled particles is presented and demonstrated to experimental data. The derivation and verification of the analytical stereological expressions used are included. Two procedures are presented for estimating the 3D size distribution of bimodal particle populations depending upon the relative size of the two particle populations. If the particles can be characterised using micrographs of the same magnification, it is possible to estimate the volume fraction of each particle population. For cases where micrographs have been taken at different magnification, an estimate of the area fractions of the particle populations is needed to combine the datasets and allow for the approximation of the 3D size distribution. These methods are useful for use in determining the initial particle size distribution for use in modelling and determining the appropriate number of micrographs and particles to measure when characterising a precipitate dispersion. Full article
(This article belongs to the Special Issue Mechanical and Microstructural Characterization of Superalloys)
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14 pages, 4657 KiB  
Article
Assessment of Structure and Properties Homogeneity after Repairing of a Nickel-Based Superalloy Product by the Electron Beam Additive Technology
by Denis Gurianov, Sergey Fortuna, Sergey Nikonov, Tatiana Kalashnikova, Andrey Chumaevskii, Veronika Utyaganova, Evgeny Kolubaev and Valery Rubtsov
Crystals 2022, 12(10), 1400; https://doi.org/10.3390/cryst12101400 - 03 Oct 2022
Cited by 4 | Viewed by 1508
Abstract
Repairing damaged products made of nickel-based superalloys is an urgent task because replacing them with new products is a costly and time-consuming process. The present work considers the method of electron-beam additive manufacturing as an approach to the repair process. First of all, [...] Read more.
Repairing damaged products made of nickel-based superalloys is an urgent task because replacing them with new products is a costly and time-consuming process. The present work considers the method of electron-beam additive manufacturing as an approach to the repair process. First of all, the initial product was produced by layer-by-layer deposition. Hereon, a part of the surface was removed, and then several more layers were deposited. Thus, three areas were considered in the work: initial, transitional, and repaired areas. Each of the formed regions was defect-free. It was found that the transition region was difficult to identify since it did not differ in structural-phase composition from the initial and repaired regions. It is shown that the complex thermal history consisting of periodic thermal exposure and repeated melting of the newly crystallized layers does not lead to the formation of defects and undesirable phases. Moreover, in all three regions, there is a redistribution of the chemical element content of the γ′ and γ phases towards an increase in the mismatch of their lattice parameters. The mechanical properties of the transition and repaired regions are not significantly different from the initial area. Full article
(This article belongs to the Special Issue Mechanical and Microstructural Characterization of Superalloys)
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12 pages, 45878 KiB  
Article
Tensile Deformation Behavior of a Directionally Solidified Superalloy at Cryogenic Temperatures
by Xiaotong Guo, Yiqiang Ni, Ganqiang Wang, Zeshan Liang, Hemeng Peng, Xiaofeng Yang and Zhiwei Fu
Crystals 2022, 12(7), 886; https://doi.org/10.3390/cryst12070886 - 22 Jun 2022
Cited by 2 | Viewed by 1782
Abstract
Ni-based superalloys are widely used to manufacture gas turbine core components, but reports on the reliability of superalloys at cryogenic temperatures are still limited. Considering the actual application of superalloys in the field of cryogenic temperature, the tensile deformation behavior of directionally solidified [...] Read more.
Ni-based superalloys are widely used to manufacture gas turbine core components, but reports on the reliability of superalloys at cryogenic temperatures are still limited. Considering the actual application of superalloys in the field of cryogenic temperature, the tensile deformation behavior of directionally solidified superalloy DZ406 was investigated at cryogenic temperatures from −125 °C to 25 °C, and the comparative analysis of room temperature and 1000 °C was carried out. The yield strength and ultimate strength at cryogenic temperatures were close to that at room temperature, and twice that at 1000 °C. The elongation was maintained at 10–15% and exhibited a certain plasticity at cryogenic temperatures. The morphologies and chemical composition of γ′ precipitates were close at cryogenic temperatures, room temperature and 1000 °C. The microstructure difference that was caused by different temperatures was mainly reflected in the fracture mode and dislocation configuration. At cryogenic temperature, the fracture samples basically exhibited no necking phenomenon, and the cracks were basically located in the interdendritic regions and occurred in MC carbide itself; at room temperature and 1000 °C, dimples with carbides inside were distributed on the fracture surface. Slip bands and dislocations contributed to the tensile deformation at cryogenic temperatures and room temperature, while only the dislocations worked at 1000 °C. Full article
(This article belongs to the Special Issue Mechanical and Microstructural Characterization of Superalloys)
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10 pages, 11647 KiB  
Article
Microstructure and High-Temperature Properties of TC31 Alloy Manufactured by Laser Melting Deposition
by Hepeng Li, Bin Guo, Yingying Zong and Debin Shan
Crystals 2022, 12(4), 475; https://doi.org/10.3390/cryst12040475 - 30 Mar 2022
Cited by 1 | Viewed by 1299
Abstract
This paper presents a comprehensive study conducted to optimize the mechanical properties for a laser-melting-deposition fabricated TC31 (Ti-Al-Sn-Zr-Mo-Nb-W-Si) alloy, which is a newly developed high-temperature alloy used in the aerospace industry. The results showed that the laser melting deposition (LMD)-built sample exhibited columnar [...] Read more.
This paper presents a comprehensive study conducted to optimize the mechanical properties for a laser-melting-deposition fabricated TC31 (Ti-Al-Sn-Zr-Mo-Nb-W-Si) alloy, which is a newly developed high-temperature alloy used in the aerospace industry. The results showed that the laser melting deposition (LMD)-built sample exhibited columnar structures with very fine α-laths inside. Annealing and solution treatment resulted in an α+β lamellar structure consisting of α-laths and β-films, of which thicknesses depended on the temperature. Solution treatment and subsequent aging did not significantly change the lamellar structure. However, aging at 650 °C led to the formation of nanoscale α precipitates within the remaining β, while aging at 750 °C resulted in coarse α precipitates. The solution-treated samples exhibited the best combination of strength and ductility at room temperature, ultimate tensile strength of 1047 MPa, and elongation of 13.0%, which is superior to the wrought TC31 counterparts. The sample after solution treatment at 980 °C and subsequent aging at 650 °C obtained an attractive combination of strength and ductility both at room temperature and high temperature due to the synergistic effect of the soft α + β lamellar structure and hard fine α precipitates. These findings provide valuable information on developments of LMD-built TC31 alloy for aerospace applications and shed light on AM of other titanium alloys with desirable high-temperature properties. Full article
(This article belongs to the Special Issue Mechanical and Microstructural Characterization of Superalloys)
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