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Characterization of Metallic Materials: Solidification, Deformation, Heat Treatment and Other Related Phenomena—Third Edition

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Metals and Alloys".

Deadline for manuscript submissions: 20 September 2025 | Viewed by 3189

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Special Issue Editors

Dr. Seong-Ho Ha

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Industrial Materials and Process R&D Department, Korea Institute of Industrial Technology (KITECH), Incheon 21999, Republic of Korea
Interests: metals and alloys; thermodynamic calculation; phase diagram; solidification; metal oxidation
Special Issues, Collections and Topics in MDPI journals

Dr. Young-Ok Yoon

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Guest Editor

Materials Supply Chain R&D Department, Korea Institute of Industrial Technology, Incheon 21999, Republic of Korea
Interests: metals and alloys; metal forming
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue features research and review articles on the characterization of metallic materials under various material conditions such as solidification, formation, and heat treatment. This Special Issue focuses on all types of characterization methods, including all forms of microscopy (transmission electron microscopy, scanning electron microscopy, etc.) and analytical techniques related to microstructure, interface, surface, etc. Studies focusing on analysis using computational science are also welcome. Recent studies dealing with the behavior of materials under various phenomena (solidification, phase transformation, oxidation, diffusion, deformation, and so on) that can occur in processes such as casting, plastic working, and heat treatment are suitable for publication in this Special Issue. This Special Issue will provide materials scientists with up-to-date information explaining the behavior of many types of metallic materials using novel approaches. This Special Issue covers all kinds of metallic materials.

Dr. Seong-Ho Ha
Dr. Young-Ok Yoon
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. Materials is an international peer-reviewed open access semimonthly 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

metals and alloys
microstructure characterization
microscopy
solidification
forming
heat treatment

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Related Special Issues

Characterization of Metallic Materials: Microstructure, Forming, and Heat Treatment in Materials (15 articles)
Characterization of Metallic Materials: Microstructure, Forming and Heat Treatment (Second Edition) in Materials (15 articles)

Published Papers (9 papers)

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Research

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19 pages, 9478 KiB

Open AccessArticle

Effect of Induction Heating Temperature on the Uniformity of Mechanical Properties of Bulb Flat Steel Sections in the Quenched State

by Zhen Qi, Xiaobing Luo, Fengrui Liang, Feng Chai, Qilu Ge, Zhide Zhan, Chunfang Wang, Wei Fan, Hong Yang and Yitong Liu

Materials 2025, 18(11), 2626; https://doi.org/10.3390/ma18112626 - 4 Jun 2025

Viewed by 84

Abstract

Induction quenching is critical for high-strength bulb flat steel, yet the influence of the heating temperature on mechanical property uniformity across sections remains underexplored. This study systematically investigates the effect of the induction heating temperature on mechanical property uniformity, prior austenite grain size, and microstructural evolution in bulb flat steel. Experimental results reveal that increasing the induction heating temperature from 845 °C to 1045 °C induces distinct mechanical responses: the yield strength disparity between the bulb and flat sections decreases by 93% (from 94 MPa), significantly improving sectional uniformity. Microstructural analysis indicates that prior austenite grain size coarsens with higher induction heating temperatures. The quenched microstructure comprises martensite and bainite in the bulb core, while the flat section is entirely martensitic. The yield strength differential between the bulb and flat sections is governed by temperature-dependent strengthening mechanisms: dislocation strengthening dominates at 845 °C~985 °C, with the bulb region exhibiting higher strength due to increased dislocation density, while grain boundary strengthening prevails at 1045 °C, where the flat region benefits from finer grains. Full article

(This article belongs to the Special Issue Characterization of Metallic Materials: Solidification, Deformation, Heat Treatment and Other Related Phenomena—Third Edition)

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16 pages, 4132 KiB

Open AccessArticle

Analysis of the Rolling Process of Alloy 6082 on a Three-High Skew Rolling Mill

by Rail Sovetbayev, Yerik Nugman, Yerzhan Shayakhmetov, Yermek Abilmazhinov, Anna Kawalek and Kirill Ozhmegov

Materials 2025, 18(11), 2618; https://doi.org/10.3390/ma18112618 - 3 Jun 2025

Viewed by 220

Abstract

Modern requirements for aluminum alloys used in mechanical engineering and aviation include increased strength characteristics and refined microstructure. One of the promising methods for improving the properties of aluminum alloys is rolling on a three-high skew rolling mill, which provides intense plastic deformation and a fine-grained structure. This study describes the results of numerical modeling of the rolling process of aluminum alloy 6082 rods in a three-high skew-type mill. Numerical modeling of alloy 6082 was conducted using the ForgeNxT 2.1 software designed to simulate metal-forming processes, including rolling. The rheological behavior of the material under study was investigated by compression tests using a Gleeble 3800 plastometer (“DSI”, Austin, TX, USA), which enabled the determination of the main parameters of material flow under specified conditions. The process of rolling bars of alloy 6082 on a three-high skew mill was numerically analyzed in the temperature range of 350–400 °C. This allowed for the study of the distribution of stresses, temperatures, and strain rates from the rolling mode. A physical experiment was conducted to validate the results of numerical modeling. The obtained results enabled the identification of rolling modes that promote microstructure refinement and enhance the mechanical properties of the alloy. Full article

(This article belongs to the Special Issue Characterization of Metallic Materials: Solidification, Deformation, Heat Treatment and Other Related Phenomena—Third Edition)

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17 pages, 5463 KiB

Open AccessArticle

The Effect of Forced Melt Flow by a Rotating Magnetic Field and Solid/Liquid Front Velocity on the Size and Morphology of Primary Si in a Hypereutectic Al-18 wt.% Si Alloy

by Dimah Zakaraia, András Roósz, Arnold Rónaföldi and Zsolt Veres

Materials 2025, 18(11), 2581; https://doi.org/10.3390/ma18112581 - 31 May 2025

Viewed by 276

Abstract

Hypereutectic Al-Si alloys containing primary Si exhibit unique material properties that make them suitable for various industrial applications. Understanding the characteristics of primary Si is crucial for predicting the effect of solidification conditions on the microstructure of these alloys. This paper presents a comprehensive characterisation study of primary Si in hypereutectic alloys. This study provides a detailed analysis of the size, distribution, and morphology of primary Si, providing valuable insights into the alloy structure, mechanical properties, and even the performance of the production process. The effect of forced melt flow by a rotating magnetic field (RMF) and solid/liquid front velocity on the size and morphology of primary Si in a hypereutectic Al-18 wt.% Si alloy was investigated. The purpose of using the RMF technique during the solidification process of Al-Si alloys is to enhance the alloy’s microstructure by inducing electromagnetic stirring. The hypereutectic samples were solidified at five different front velocities (0.02, 0.04, 0.08, 0.2, and 0.4 mm/s), under an average temperature gradient (G) of 8 K/mm, in a crystalliser equipped with an RMF inductor. Each sample was divided into two parts: the first solidified without stirring, while the second underwent electromagnetic stirring using RMF at an induction (B) of 7.2 mT. The results revealed that increasing the front velocity during solidification refined the primary Si in stirred and non-stirred parts. In non-stirred parts, it decreased dendritic forms and increased star-like Si, while polyhedral shapes remained nearly constant. Stirred parts showed stable Si morphology across velocities. Higher velocities also promoted equiaxed over elongated Si forms in both parts. Full article

(This article belongs to the Special Issue Characterization of Metallic Materials: Solidification, Deformation, Heat Treatment and Other Related Phenomena—Third Edition)

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17 pages, 4544 KiB

Open AccessArticle

Hot Compression Behavior and Processing Maps of 6063 Aluminum Alloy Under Medium Strain Rate

by Zhenhu Wang, Qincan Shen, Shuang Chen, Lijun Dong, Erli Xia, Pengcheng Guo and Yajun Luo

Materials 2025, 18(11), 2510; https://doi.org/10.3390/ma18112510 - 27 May 2025

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Abstract

A hot compression test was conducted across a range of temperatures (350, 400, 450, and 500 °C) and varying strain rates (0.001–10 s⁻¹) to explore the hot compression behavior of the 6063 alloy. Hot processing maps were obtained based on the stress–strain curves. Optimal processing parameters were identified as residing within the intervals of (470–500 °C, 0.01–0.1108 s⁻¹), achieving a maximum dissipation efficiency of 0.4, which is of great importance for perfecting hot processing. The microstructure evolution was characterized using an optical microscope and a transmission electron microscope. The initial grains were elongated under compressive deformation, and the density of dislocation rose with increasing strain rate and decreasing temperature. Dynamic recovery serves as the main dynamic softening mechanism during hot compression. Full article

(This article belongs to the Special Issue Characterization of Metallic Materials: Solidification, Deformation, Heat Treatment and Other Related Phenomena—Third Edition)

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10 pages, 4148 KiB

Open AccessArticle

The Recrystallized Microstructures and Mechanical Properties of a Hypo-Eutectic Al₁₃Ni₃₆Cr₁₀Fe₄₀Mo₁ High-Entropy Alloy

by Hui Li, Han Wang, Xiaoyu Bai, Peng Yan, Linxiang Liu, Chuwen Wang, Yunji Qiu and Zhijun Wang

Materials 2025, 18(11), 2454; https://doi.org/10.3390/ma18112454 - 23 May 2025

Viewed by 308

Abstract

Recrystallization is a critical process for tailoring the microstructure to enhance the mechanical properties of alloys. In duplex-phase alloys, the recrystallization is different due to the influence of the second phase. Hypo-eutectic high-entropy alloys (HEAs) with two phases are promising structural materials. Understanding the laws of microstructure and mechanical properties during recrystallization is essential for fabrication and application. Here, we systematically investigate the influence of recrystallization time on the microstructure and mechanical properties of an as-cast hypo-eutectic high-entropy alloy (HEA), Al₁₃Ni₃₆Cr₁₀Fe₄₀Mo₁. As the recrystallization time increases from 10 min to 8 h at 1100 °C, the cold-rolled alloy gradually completed the recrystallization process with a residual large B2 phase and equiaxed FCC grains decorated with B2 precipitation. The average grain size of the FCC phase increases slightly from 2.60 μm to 3.62 μm, while the fine B2 phase precipitates along the FCC phase’s grain boundaries. This optimized microstructure significantly improves the alloy’s tensile strength from 422 MPa to 877 MPa, while maintaining a substantial plasticity of 41%, achieving an excellent strength–ductility balance. These findings provide useful information for regulating the industrial thermomechanical treatment of dual-phase hypo-eutectic high-entropy alloys. Full article

(This article belongs to the Special Issue Characterization of Metallic Materials: Solidification, Deformation, Heat Treatment and Other Related Phenomena—Third Edition)

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16 pages, 8574 KiB

Open AccessArticle

Investigation of the Microstructure and Mechanical Performance of GH4099 Alloy Fabricated by Selective Laser Melting

by Bo Chen, Yilong Zhong, Wenying Li, Yanying Li, Qiyou Wang, Yingjie Lu, Zichen Qi, Shenqi Wang and Yanbiao Li

Materials 2025, 18(10), 2271; https://doi.org/10.3390/ma18102271 - 14 May 2025

Viewed by 293

Abstract

GH4099 is a nickel-based, high-temperature, precipitation-strengthened alloy with excellent mechanical properties and corrosion resistance, widely used in aerospace components. The performance of parts produced by additive manufacturing depends significantly on alloy powder quality and heat treatment. In this study, GH4099 alloy powder was prepared using the EIGA method, and its morphology, particle size distribution, and flowability were analyzed. The mechanical properties and microstructure of parts before and after solution-aging treatment were compared. Results showed that the powder had good sphericity and flowability, with a median diameter D50 of 28.88 μm. The formed parts underwent solution treatment at 1140 °C for 2 h followed by aging at 850 °C for 8 h. After heat treatment, the transverse tensile strength increased to 1122.11 MPa (+15.1%) and the yield strength to 866.56 MPa (+22.3%), while the longitudinal tensile strength reached 1116.81 MPa (+29.4%) and the yield strength 831.61 MPa (+35.2%). This improvement is attributed to the precipitation of γ′ phase. Fractographic analysis revealed a mixed fracture mode characterized by ductile dimples and cleavage facets, indicating that the alloy exhibits favorable toughness-related features under mechanical loading. These findings demonstrate the excellent microstructure and mechanical performance of GH4099 alloy in AM applications, providing a basis for its further use in high-performance aerospace components. Full article

(This article belongs to the Special Issue Characterization of Metallic Materials: Solidification, Deformation, Heat Treatment and Other Related Phenomena—Third Edition)

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11 pages, 3535 KiB

Open AccessArticle

Effect of Fe Content on Phase Behavior of Sm–Co–Fe Alloys During Solidification and Aging

by Zhi Zhu, Yikun Fang, Wei Wu, Bo Zhao, Meng Zheng, Ming Lei and Jiashuo Zhang

Materials 2025, 18(8), 1854; https://doi.org/10.3390/ma18081854 - 17 Apr 2025

Viewed by 366

Abstract

The effect of different Fe contents on the phases of Sm–Co–Fe ternary alloys during solidification is investigated herein by melting the alloys using a non-consumable vacuum arc furnace. In particular, the phases of the Sm_25.5Co_balFe_x (x = 19, 21, 23, and 25 wt.%) alloys are investigated after solidification and aging. The results obtained from Cai Li’s modified Miedema model show a strong interaction between the Sm–Co alloy atoms. Additionally, the results obtained from the Toop geometric model show a strong interaction between the Sm–Co–Fe ternary alloy atoms, enabling the formation of intermetallic compounds. The experimental results show that when the Sm content is 25.5 wt.%, the SmCo₅ phase gradually decreases as the Fe content increases and disappears when the Fe content is 25 wt.%. Thermodynamic calculations show that when the Fe content is 19 wt.%, there is a region where the SmCo₅ and Sm₂Co₁₇ phases co-exist. As the Fe content increases, this region gradually decreases. For a 25 wt.% Fe content, the Sm₂Co₁₇ and SmCo₅ two-phase region does not appear when the Sm content varies. The samples are aged at 1143 °C for 12 h, then melted and cut. The phase results obtained by scanning are consistent with the calculated results. In this study, the effect of each constituent element of Sm–Co–Fe ternary alloys on their solidification phases is investigated, providing a strong foundation for studying the 2:17-type Sm–Co magnetic materials obtained after melting and aging a five-element Sm–Co alloy. Full article

(This article belongs to the Special Issue Characterization of Metallic Materials: Solidification, Deformation, Heat Treatment and Other Related Phenomena—Third Edition)

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14 pages, 10319 KiB

Open AccessArticle

Effect of Transition Layers on the Microstructure and Properties of CMT Additively Manufactured Steel/Copper Specimens

by Xuyang Guo, Yulang Xu, Jingyong Li and Cheng Zhang

Materials 2025, 18(8), 1734; https://doi.org/10.3390/ma18081734 - 10 Apr 2025

Viewed by 390

Abstract

During the cold metal transfer (CMT) arc additive manufacturing process of steel/copper bimetallic materials, interfacial penetration cracks have been observed due to the significant differences in thermal and physical properties between steel and copper. To mitigate the occurrence of these penetration cracks and enhance the interfacial elemental diffusion at the steel/copper junction, this study aims to fabricate high-performance steel/copper bimetallic materials with a uniform microstructure using CMT arc additive manufacturing techniques. A reciprocating additive sequence was adopted, with steel deposited first, followed by copper. Four different interlayer compositions, Cu-Ni, Fe-Ni, Cu-Cr, and Ni-Cr, were applied to the steel surface before the deposition of aluminum bronze. These interlayers served as a transition between the steel and copper materials. The manufacturing process then continued with the deposition of aluminum bronze to achieve the desired bimetallic structure. After the addition of interlayers, all four sets of samples exhibited excellent macroscopic formability, with clear and smooth interlayer contours and no visible cracks or collapse defects at the junction interfaces. The mechanical properties of the composite walls were enhanced following the addition of the interlayers, with an increase in tensile strength observed across the samples. The sample with the Fe-Ni interlayer showed the most significant improvement, with a 52% increase in impact energy absorption. Furthermore, the sample with the Fe-Ni interlayer demonstrated a higher average hardness level than the other groups, which was associated with the distribution and content of the iron-rich phase and the β′ phase. Full article

(This article belongs to the Special Issue Characterization of Metallic Materials: Solidification, Deformation, Heat Treatment and Other Related Phenomena—Third Edition)

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Review

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17 pages, 1688 KiB

Open AccessReview

Application of Machine Learning in Amorphous Alloys

by Like Zhang, Huangyou Zhang, Boyan Ji, Leqing Liu, Xianlan Liu and Ding Chen

Materials 2025, 18(8), 1771; https://doi.org/10.3390/ma18081771 - 13 Apr 2025

Viewed by 479

Abstract

In the past few decades, traditional methods for developing amorphous alloys, such as empirical trial-and-error approaches and density functional theory (DFT)-based calculations, have enabled researchers to explore numerous amorphous alloy systems and investigate their properties. However, these methods are increasingly unable to meet the demands of modern research due to their long development cycles and low efficiency. In contrast, machine learning (ML) has gained widespread adoption in the design, analysis, and property prediction of amorphous alloys due to its advantages of low experimental cost, powerful performance, and short development cycles. This review focuses on four key applications of ML in amorphous alloys: (1) prediction of amorphous alloy phases, (2) prediction of amorphous composite phases, (3) prediction of glass-forming ability (GFA), and (4) prediction of material properties. Finally, we outline future directions for ML in materials science, including the development of more sophisticated models, integration with high-throughput experimentation, and the creation of standardized data-sharing platforms. These insights provide potential research directions and frameworks for subsequent studies in this field. Full article

(This article belongs to the Special Issue Characterization of Metallic Materials: Solidification, Deformation, Heat Treatment and Other Related Phenomena—Third Edition)

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