Advances in Lightweight Alloys

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Metal Casting, Forming and Heat Treatment".

Deadline for manuscript submissions: 30 November 2024 | Viewed by 5384

Special Issue Editors


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Guest Editor
Research Institute for Frontier Science, Beihang University, Beijing, 100191, China
Interests: aluminum alloy; Ni-based superalloy; casting; forming; solidification

E-Mail Website
Guest Editor
Research Institute for Frontier Science, Beihang University, Beijing, 100191, China
Interests: advanced aluminum; aluminum-based composite; Nb-Si based alloy

Special Issue Information

Dear Colleagues,

We are delighted to organize a Special Issue focusing on advances in lightweight alloys. To meet the requirement of energy saving and emission reduction, lightweight alloys have been widely used in aerospace, automotive, and railway transportation, and so on. Recent research advances enable a better understanding of the relationship between lightweight alloys’ composition, microstructure, process, and properties. The papers presented in this Special Issue contain valuable information about the composition design, preparation process, casting, solidification, microstructure, and property analysis of lightweight alloys, including but not limited to aluminum alloy, magnesium alloy, titanium alloy, and lightweight nickel-based superalloy. We hope this Special Issue will contribute to the ongoing discussions on designing high-performance lightweight alloys and developing advanced processing technology.

Dr. Huarui Zhang
Dr. Lina Jia
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. Metals 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.

Keywords

  • aluminum alloy
  • magnesium alloy
  • titanium alloy
  • Ni-based superalloy
  • composition design
  • processing technology
  • microstructure analysis
  • mechanical properties

Published Papers (6 papers)

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Research

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15 pages, 28225 KiB  
Article
Effect of Force and Heat Coupling on Machined Surface Integrity and Fatigue Performance of Superalloy GH4169 Specimens
by Xun Li, Ruijie Gou and Ning Zhang
Metals 2024, 14(5), 540; https://doi.org/10.3390/met14050540 - 2 May 2024
Viewed by 546
Abstract
GH4169 is one of the key materials used to manufacture high-temperature load-bearing parts for aero-engines, and the surface integrity of these parts in service conditions significantly affects their high-temperature fatigue performance. Under a coupling effect of high temperature and alternating load, the evolution [...] Read more.
GH4169 is one of the key materials used to manufacture high-temperature load-bearing parts for aero-engines, and the surface integrity of these parts in service conditions significantly affects their high-temperature fatigue performance. Under a coupling effect of high temperature and alternating load, the evolution process of the machined surface integrity index of superalloy GH4169 specimens was studied, and fatigue performance tests at 20 °C, 450 °C, and 650 °C were carried out to analyze the primary factors affecting the high-temperature fatigue performance of specimens. The results indicated that the surface roughness of specimens remained essentially unchanged. However, the value of surface residual stress decreased significantly, with a release of more than 60% at the highest temperature. At 650 °C, the surface microhardness increased, while the degree of surface plastic deformation decreased under alternating loads. Simultaneously, when the surface roughness was less than Ra 0.4 μm, surface microhardness was the main factor affecting the high-temperature fatigue performance of specimens. The influence of surface microhardness on low-cycle fatigue performance was not consistent with that on high-cycle fatigue performance. The latter increased monotonically, whereas the former initially increased and then decreased with increasing surface microhardness. Full article
(This article belongs to the Special Issue Advances in Lightweight Alloys)
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15 pages, 12444 KiB  
Article
The Effect of Refined Coherent Grain Boundaries on High-Temperature Oxidation Behavior of TiAl-Based Alloys through Cyclic Heat Treatment
by Keren Zhang, Lele Zhang and Jinguang Li
Metals 2024, 14(5), 521; https://doi.org/10.3390/met14050521 - 29 Apr 2024
Viewed by 469
Abstract
The grain size of the full lamellae TiAl-based alloy changes from ~400 μm to ~40 μm through the precipitation of metastable structures by cyclic heat treatment. Based on this, two kinds of variant selection processes—coherent metastable γ variants precipitated during the air-cooling process [...] Read more.
The grain size of the full lamellae TiAl-based alloy changes from ~400 μm to ~40 μm through the precipitation of metastable structures by cyclic heat treatment. Based on this, two kinds of variant selection processes—coherent metastable γ variants precipitated during the air-cooling process and αs variants precipitated during the holding at a single α phase region process—are identified to promote the formation of refined Type I and Type II coherent grain boundaries. The oxidation tests at 1000 °C for 100 h show that the formation of refined coherent grain boundaries can greatly improve oxidation resistance by inducing the continuous multi-layer protective barrier consisting of (Ti, (Nb, Ta))O2, TiN, and Al(Nb,Ta)2. This protective barrier inhibits the inward diffusion of oxygen and nitrogen. Full article
(This article belongs to the Special Issue Advances in Lightweight Alloys)
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12 pages, 4541 KiB  
Article
The Influence of Aging Precipitates on the Mechanical Properties of Al–Li Alloys and Microstructural Analysis
by Ganghui Li, Wei Xiao, Xiwu Li, Kai Wen, Guanjun Gao, Lizhen Yan, Yanan Li, Hongwei Yan, Yongan Zhang, Xingquan Wang and Baiqing Xiong
Metals 2024, 14(5), 506; https://doi.org/10.3390/met14050506 - 26 Apr 2024
Viewed by 567
Abstract
In this work, the evolution of mechanical properties of binary Al–Li alloys with four approximately equal gradient Li contents (0.91–3.98 wt.%) under aging conditions is thoroughly investigated. The alloys undergo aging treatments at 175 °C for x hours (x = 0–120 h), and [...] Read more.
In this work, the evolution of mechanical properties of binary Al–Li alloys with four approximately equal gradient Li contents (0.91–3.98 wt.%) under aging conditions is thoroughly investigated. The alloys undergo aging treatments at 175 °C for x hours (x = 0–120 h), and the peak-aged times of the four alloys are 6 h, 12 h, 48 h and 48 h, respectively, as the Li concentration increases. Both in the solution-treated and peak-aged states, the elastic modulus of binary Al–Li alloys exhibits an approximately linear increase with increasing Li content, consistent with trends predicted by density functional theory (DFT) calculations. Due to the presence of Al3Li precipitates, the modulus of higher-Li-concentration alloys in the peak-aged state increases by approximately 1.4–2.5% compared with that of alloys in the solution-treated state. Additionally, the study finds that increasing Li content significantly enhances the tensile strength and yield strength of the alloy but decreases its ductility, leading to a transition in fracture mode from ductile to brittle, as evidenced by a microscopic analysis of fracture surfaces. Under peak-aged (175 °C/48 h), the alloy with the highest Li content exhibits the maximum tensile strength of 341 MPa and a yield strength of 296 MPa, while its elongation is the lowest at 2.1%. These findings contribute to a deeper understanding of the effects of aging precipitates on the mechanical properties of Al–Li alloys, providing fundamental guidance for the design of future generations of Al–Li alloys. Full article
(This article belongs to the Special Issue Advances in Lightweight Alloys)
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17 pages, 9189 KiB  
Article
The Effect of Microstructure on the Very High Cycle Fatigue Behavior of Ti-6Al-4V Alloy
by Mingyang Yuan, Xinbao Zhao, Quanzhao Yue, Yuefeng Gu and Ze Zhang
Metals 2024, 14(3), 254; https://doi.org/10.3390/met14030254 - 20 Feb 2024
Cited by 1 | Viewed by 1108
Abstract
Crack initiation plays a major role in very high cycle fatigue (VHCF) life, and the initiation of cracks is related to slip behavior. There is a need for improvement in the understanding of the influence of Ti-6Al-4V microstructures on VHCF performance and crack [...] Read more.
Crack initiation plays a major role in very high cycle fatigue (VHCF) life, and the initiation of cracks is related to slip behavior. There is a need for improvement in the understanding of the influence of Ti-6Al-4V microstructures on VHCF performance and crack initiation modes. In this study, through an investigation of Ti-6Al-4V VHCF in equiaxed and bimodal microstructures, two different crack initiation modes were identified. The change in crack initiation mode is related to the variation in microtexture, for which a corresponding model is proposed. The VHCF performance of the bimodal microstructure is significantly improved compared to that of the equiaxed microstructure. Full article
(This article belongs to the Special Issue Advances in Lightweight Alloys)
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16 pages, 2205 KiB  
Article
Coexistence of Intermetallic Complexions and Bulk Particles in Grain Boundaries in the ZEK100 Alloy
by Boris Straumal, Kristina Tsoy, Aleksandr Druzhinin, Valery Orlov, Natalya Khrapova, Gregory Davdian, Gregory Gerstein and Alexander Straumal
Metals 2023, 13(8), 1407; https://doi.org/10.3390/met13081407 - 6 Aug 2023
Cited by 4 | Viewed by 1369
Abstract
Magnesium-based alloys are highly sought after in the industry due to their lightweight and reliable strength. However, the hexagonal crystal structure of magnesium results in the mechanical properties’ anisotropy. This anisotropy is effectively addressed by alloying magnesium with elements like zirconium, zinc, and [...] Read more.
Magnesium-based alloys are highly sought after in the industry due to their lightweight and reliable strength. However, the hexagonal crystal structure of magnesium results in the mechanical properties’ anisotropy. This anisotropy is effectively addressed by alloying magnesium with elements like zirconium, zinc, and rare earth metals (REM). The addition of these elements promotes rapid seed formation, yielding small grains with a uniform orientation distribution, thereby reducing anisotropy. Despite these benefits, the formation of intermetallic phases (IP) containing Zn, Zr, and REM within the microstructure can be a concern. Some of these IP phases can be exceedingly hard and brittle, thus weakening the material by providing easy pathways for crack propagation along grain boundaries (GBs). This issue becomes particularly significant if intermetallic phases form continuous layers along the entire GB between two neighboring GB triple junctions, a phenomenon known as complete GB wetting. To mitigate the risks associated with complete GB wetting and prevent the weakening of the alloy’s structure, understanding the potential occurrence of a GB wetting phase transition and how to control continuous GB layers of IP phases becomes crucial. In the investigation of a commercial magnesium alloy, ZEK100, the GB wetting phase transition (i.e., between complete and partial GB wetting) was successfully studied and confirmed. Notably, complete GB wetting was observed at temperatures near the liquidus point of the alloy. However, at lower temperatures, a coexistence of a nano-scaled precipitate film and bulk particles with nonzero contact angles within the same GB was observed. This insight into the wetting transition characteristics holds potential to expand the range of applications for the present alloy in the industry. By understanding and controlling GB wetting phenomena, the alloy’s mechanical properties and structural integrity can be enhanced, paving the way for its wider utilization in various industrial applications. Full article
(This article belongs to the Special Issue Advances in Lightweight Alloys)
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Review

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21 pages, 534 KiB  
Review
A Review of the State of Art of Fabrication Technologies of Titanium Aluminide (Ti-Al) Based on US Patents
by Shawdon Huang, Yu-Chien Lin and Ren-Jei Chung
Metals 2024, 14(4), 418; https://doi.org/10.3390/met14040418 - 1 Apr 2024
Viewed by 820
Abstract
This article evaluates the fabrication technologies of titanium aluminide (Ti-Al) and its practical applications by comparing it with the well-known Ti-Al binary phase diagram and US patents. Meanwhile, by analyzing and discussing the various patented Ti-Al fabrication technologies and applications, this article discusses [...] Read more.
This article evaluates the fabrication technologies of titanium aluminide (Ti-Al) and its practical applications by comparing it with the well-known Ti-Al binary phase diagram and US patents. Meanwhile, by analyzing and discussing the various patented Ti-Al fabrication technologies and applications, this article discusses the applications of Ti-Al-based alloys, mainly in the aircraft field. The improved fabrication processes and new application technologies are under patent protection. These technologies are classified into six categories: basic research on Ti-Al-based alloys, powder metallurgy of Ti-Al-based alloys, casting and melting of Ti-Al-based alloys, PM and AM manufacturing methods for aircraft applications, other fabrication technologies by Ti-Al-based alloys, and self-propagating high-temperature synthesis (SHS) of Ti-Al-based alloys. By comparing the principles and characteristics of the above techniques, the advantages, disadvantages, and application fields of each are analyzed and their developments are discussed. Based on the characteristics of Ti-Al, new fabrication and application technologies can be developed, which can overcome the existing disadvantages and be used to form new aircraft components. Full article
(This article belongs to the Special Issue Advances in Lightweight Alloys)
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