Microstructural Tailoring of Metals and Alloys

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: 20 September 2024 | Viewed by 7571

Special Issue Editors


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Guest Editor
Division of Materials of Energy Interest, CIEMAT, Avenida Complutense 40, 28040 Madrid, Spain
Interests: steels; microscopy

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Guest Editor
Department of Physical Metallurgy, CENIM, Avenida Gregorio del Amo 8, 28040 Madrid, Spain
Interests: microstructure; light alloys; microscopy

Special Issue Information

Dear Colleagues,

The development of high-performance structural metallic materials is essential in many different industrial areas where materials are submitted to harsh environments. The aim of this Special Issue focuses on the optimization of the microstructure of metals and alloys to achieve the required performance under service conditions, modifying different parameters during fabrication routes, such as the control of the alloy chemistry and processing techniques. This Special Issue will be dedicated to a wide range of contributions, starting with those works based on computational metallurgy to improve and design alloys, followed by those focused on the fabrication routes (casting, powder metallurgy, additive manufacturing, etc.) and post-fabrication processing techniques (thermomechanical processes, heat treatments, combinations thereof, etc.). Finally, papers regarding the characterization of microstructural and mechanical properties will also be part of this issue. Studies of light alloys, high-entropy alloys (HEAs), alumina-forming alloys (AFAs), oxide dispersion strengthened alloys (ODSs), advanced steels, and other innovative metallic materials will be welcomed.

Dr. Elvira Oñorbe
Dr. Judit Medina
Guest Editors

Manuscript Submission Information

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Keywords

  • alloy chemistry
  • processing technologies
  • microstructure optimization
  • microstructural characterization
  • computational metallurgy
  • mechanical characterization

Published Papers (5 papers)

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Research

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22 pages, 4661 KiB  
Article
Microstructure Tailoring for High Strength Ti-6Al-4V without Alloying Elements through Optimized Preheating and Post-Heating Laser Scanning in Laser Powder Bed Fusion
by Ahmet Alptug Tanrikulu, Aditya Ganesh-Ram, Hamidreza Hekmatjou, Sadman Hafiz Durlov, Md Najmus Salehin and Amirhesam Amerinatanzi
Metals 2024, 14(6), 629; https://doi.org/10.3390/met14060629 - 26 May 2024
Viewed by 507
Abstract
Ti-6Al-4V with its eclectic array of excellent properties along with the combination of meticulous precision and flexibility offered by the laser powder bed fusion (LPBF) technology makes it a strong proponent in the field of engineering applications. As a substantial amount of research [...] Read more.
Ti-6Al-4V with its eclectic array of excellent properties along with the combination of meticulous precision and flexibility offered by the laser powder bed fusion (LPBF) technology makes it a strong proponent in the field of engineering applications. As a substantial amount of research has paved the way to fabricate Ti-6AL-4V more effectively and efficiently, researchers are becoming more adventurous in finding out the optimal techniques to get better yields in terms of mechanical responses. This includes post-processing techniques i.e., heat treatment (HT) or introducing various alloying elements. Nevertheless, these techniques not only make the overall fabrication more expensive and time-consuming but also contradict the simplistic notion of additive manufacturing (AM) by imparting multistage fabrication without a considerable improvement overall. Here, we propose an innovative breakthrough in the field of Ti-6AL-4V fabrication with LPBF by introducing an in-situ approach to tackle the handicap mentioned in contemporary studies. By imparting multiple laser scans prior to and after the melting scan at each layer, a remarkable 37% improvement in yield strength (YS) can be achieved with higher elongation, while also maintaining a high relative density of around 99.99%. Full article
(This article belongs to the Special Issue Microstructural Tailoring of Metals and Alloys)
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18 pages, 7700 KiB  
Article
Microstructure Evolution and Numerical Modeling of TC4 Titanium Alloy during Ultrasonic Shot Peening Process
by Yuxuan Yi, Fei Yin, Jiajun Zhai and Yanxiong Liu
Metals 2024, 14(3), 275; https://doi.org/10.3390/met14030275 - 27 Feb 2024
Cited by 1 | Viewed by 1270
Abstract
Ultrasonic shot peening (USP) is a surface treatment technology used in the mechanical properties strengthening of the engineering material and components during manufacturing. TC4 titanium alloy is a commonly used engineering material in the aerospace industry. In this study, a gradient nanostructured surface [...] Read more.
Ultrasonic shot peening (USP) is a surface treatment technology used in the mechanical properties strengthening of the engineering material and components during manufacturing. TC4 titanium alloy is a commonly used engineering material in the aerospace industry. In this study, a gradient nanostructured surface layer was successfully fabricated on the TC4 titanium alloy via USP technology at room temperature. The microstructure evolution of TC4 titanium alloy during USP was investigated. The surface microhardness was elevated from 330 HV to 438 HV with a penetrating depth of around 900 μm after USP with the duration of 8 min. EBSD characterization results confirmed the presence of high-density grain boundaries within the gradient structure in the region of 0–200 μm, accompanied by proliferation of dislocation density. TEM characterization indicated a substantial amount of nanograin with an average size of 74.58 nm. Furthermore, the USP process was also investigated by the finite element method to evaluate the surface-strengthening effect. The calculated maximum residual stress reached 973 MPa after multi-ball impact. The impact behavior of the shots during the USP process was studied. The effect of the parameters on the USP strengthening intensity was explored based on the validated model. This work provided a clearer understanding of the USP strengthening process of TC4 titanium alloy through an effective method of evaluating the process parameters. Full article
(This article belongs to the Special Issue Microstructural Tailoring of Metals and Alloys)
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16 pages, 13540 KiB  
Article
Microstructural Evolution and Material Flow during Friction Stir Welding of 6013 Aluminum Alloy Studied by the Stop-Action Technique
by Alexander Kalinenko, Pavel Dolzhenko, Sergey Malopheyev, Ivan Shishov, Vasiliy Mishin, Sergey Mironov and Rustam Kaibyshev
Metals 2023, 13(8), 1342; https://doi.org/10.3390/met13081342 - 27 Jul 2023
Cited by 1 | Viewed by 1028
Abstract
This work is part of a wide-ranging study aiming to enhance the technology of dissimilar friction-stir welding of aluminum and titanium. In the previous study, a new approach was proposed that provided an exceptionally narrow intermetallic layer. However, an essential disadvantage of this [...] Read more.
This work is part of a wide-ranging study aiming to enhance the technology of dissimilar friction-stir welding of aluminum and titanium. In the previous study, a new approach was proposed that provided an exceptionally narrow intermetallic layer. However, an essential disadvantage of this technique was the significant material softening in the aluminum part. Hence, the present work was undertaken in order to obtain insight into microstructural processes and material flow in the aluminum part. To this end, the stop-action technique was applied. It was found that the microstructural evolution included several stages. Specifically, the initial material underwent the discontinuous static recrystallization in the heat-affected zone. With the approach of the rotating tool, the recrystallized grains experienced continuous dynamic recrystallization, which resulted in grain refinement. The subsequent transportation of material around the rotating tool provided no significant alterations in microstructure. This “superplastic-like” character of material flow was attributed to a dynamic balance between grain refinement and grain coarsening. It was also found that the stirred material experienced a secondary deformation induced by the rotating tool shoulder far behind the welding tool. The concomitant microstructural changes were most pronounced at the upper weld surface and gave rise to a fine-grained layer. Full article
(This article belongs to the Special Issue Microstructural Tailoring of Metals and Alloys)
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16 pages, 12117 KiB  
Article
Control of the Microstructure in a Al5Co15Cr30Fe25Ni25 High Entropy Alloy through Thermo-Mechanical and Thermal Treatments
by Pablo Pérez, Judit Medina, María Fernanda Vega, Gerardo Garcés and Paloma Adeva
Metals 2023, 13(1), 180; https://doi.org/10.3390/met13010180 - 16 Jan 2023
Cited by 4 | Viewed by 1681
Abstract
The effect of thermos-mechanical processing and thermal treatments on the microstructure of a single phase fcc-based Al5Co15Cr30Fe25Ni25 high entropy alloy is evaluated in this study. As-cast ingots of the high entropy alloy were thermo-mechanically [...] Read more.
The effect of thermos-mechanical processing and thermal treatments on the microstructure of a single phase fcc-based Al5Co15Cr30Fe25Ni25 high entropy alloy is evaluated in this study. As-cast ingots of the high entropy alloy were thermo-mechanically processed following different routes involving forging, cold rolling, warm rolling or hot rolling. In addition, the microstructural evolution of highly deformed cold rolled sheets with the annealing temperature was analyzed. The data reveal that a high-volume fraction of the microstructure commences to recrystallize from 600 °C. In the absence of recrystallization, i.e., below 600 °C, the hardness of thermo-mechanically processed and annealed samples was very close. When recrystallization takes place, the thermo-mechanically treated alloys exhibit higher hardness than the annealed alloys because the recrystallized grains are strengthened by dislocations generated in further steps of the processing while the alloys in the annealed condition are free of dislocations. Maximum hardening is found for the alloy warm-rolled at 450 °C and the alloy cold-rolled plus annealing at 500 °C for 1 h. Diffusion of solute atoms to the core of dislocations, pinning its movement, accounts for the additional hardening. Full article
(This article belongs to the Special Issue Microstructural Tailoring of Metals and Alloys)
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Review

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17 pages, 3469 KiB  
Review
A Critical Review on Al-Co Alloys: Fabrication Routes, Microstructural Evolution and Properties
by Athanasios K. Sfikas, Sergio Gonzalez, Angeliki G. Lekatou, Spyros Kamnis and Alexandros E. Karantzalis
Metals 2022, 12(7), 1092; https://doi.org/10.3390/met12071092 - 26 Jun 2022
Cited by 3 | Viewed by 2396
Abstract
Al-Co alloys is an emerging category of metallic materials with promising properties and potential application in various demanding environments. Over the years, different manufacturing techniques have been employed to fabricate Al-Co alloys, spanning from conventional casting to rapid solidification techniques, such as melt [...] Read more.
Al-Co alloys is an emerging category of metallic materials with promising properties and potential application in various demanding environments. Over the years, different manufacturing techniques have been employed to fabricate Al-Co alloys, spanning from conventional casting to rapid solidification techniques, such as melt spinning, thus leading to a variety of different microstructural features. The effect of the fabrication method on the microstructure is crucial, affecting the morphology and volume of the precipitates, the formation of supersaturated solid solutions and the development of amorphous phases. In addition, the alloy composition has an effect on the type and volume fraction of intermetallic phases formed. As a result, alloy properties are largely affected by the microstructural outcomes. This review focuses on highlighting the effect of the fabrication techniques and composition on the microstructure and properties of Al-Co alloys. Another goal is to highlight areas in the field that are not well understood. The advantages and limitations of this less common category of Al alloys are being discussed with the scope of future prospects and potential applications. Full article
(This article belongs to the Special Issue Microstructural Tailoring of Metals and Alloys)
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