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A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Metallic Functional Materials".

Deadline for manuscript submissions: closed (31 July 2024) | Viewed by 18625

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Special Issue Editors

Prof. Dr. Victorino Franco

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Department of Condensed Matter Physics, University of Seville, 41080 Seville, Spain
Interests: magnetic materials for energy applications; soft magnetic materials; thermomagnetic phase transitions; caloric effects

Dr. João Horta Belo

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The Institute of Physics for Advanced Materials Nanotechnology and Photonics (IFIMUP), Universidade do Porto, 4169-007 Porto, Portugal
Interests: magnetic materials; magnetocaloric materials; phase transitions; micro-nanostructuring; energy harvesting; thermomechanical applications; biomedical applications

Dr. Luis Miguel Moreno-Ramírez

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Department of Condensed Matter Physics, University of Seville, 41080 Seville, Spain
Interests: magnetic materials; amorphous, nanocrystalline and intermetallic alloys; magnetocaloric effect; thermomagnetic phase transitions

Special Issue Information

Dear Colleagues,

This Special Issue, which we invite papers for, contains a representative sample of some of the most relevant current topics in metallic functional materials.

The classification between structural and functional materials is usually made via exclusion. Structural materials are suitable for applications based on their load-bearing capacity and on their mechanical properties. Functional materials, on the other hand, have a more extended range of applications, since they encompass magnetic, electric, or optical properties (and often couplings between these), to mention just a few. In this sense, functional materials have a phenomenology that is much broader than that of structural materials, and the discovery of new applications would consequently expand the field, creating new subclasses. Therefore, the section of Metals ‘Metallic Functional Materials’, to which this Special Issue belongs, is open to a wide range of materials (with the obvious requirement of being metallic materials), an extended set of properties, and a diverse spectrum of applications.

From a compositional point of view, borderline cases in which functionality plays a relevant role are also of particular interest to us. Besides bulk or metallic materials with reduced dimensionality, metal-containing composites for functional applications would also fit this section, provided that the metallic fraction of the composite is responsible for the desired functional properties. From a property point of view, improving the mechanical performance of functional materials to enhance the reliability, durability, and sustainability of functional parts would also be appropriate for this section.

The focus of this Special Issue is on the development of new or optimized metallic functional materials, the advancement of modeling and simulation techniques that can predict their functional properties, experimental techniques related to the characterization of these properties, and novel applications that exploit the material’s functionalities.

Prof. Dr. Victorino Franco
Dr. João Horta Belo
Dr. Luis Miguel Moreno-Ramírez
Guest Editors

Manuscript Submission Information

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Keywords

magnetic properties
electric properties
optical properties
shape memory alloys
magnetovolume coupling
magnetocaloric effect
elastocaloric effect
multicaloric materials
metal–polymer composites
nanostructured metallic materials
functional thin films
modeling and simulation
advanced experimental techniques

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Published Papers (10 papers)

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Research

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16 pages, 9731 KiB

Open AccessArticle

Superelastic Properties of Aged FeNiCoAlTaB Cold-Rolled Shape Memory Alloys

by Li-Wei Tseng, Miao Song, Wei-Cheng Chen, Yi-Ting Hsu and Chih-Hsuan Chen

Metals 2024, 14(6), 643; https://doi.org/10.3390/met14060643 - 28 May 2024

Viewed by 767

Abstract

In the present study, microstructure and cyclic tensile tests were used to measure the superelastic responses of Fe_40.95Ni₂₈Co₁₇Al_11.5Ta_2.5B_0.05 (at.%) shape memory alloys after 97% cold rolling. Cold-rolled samples underwent annealing heat treatment (1250 °C/1 h) followed by quenching in water or aging heat treatment (700 °C/6 h and 700 °C/12 h) followed by quenching in water. The microstructure results showed that the average grain size increased from 210 μm to 1570 μm as annealing times increased from 0.5 h to 1 h. X-ray diffraction (XRD) spectra for FeNiCoAlTaB (NCATB) showed that in cold-rolled alloys after solution, the strong peak was in the face-centered cubic (γ, FCC) <111> structure. In aged samples, a new peak (γ’, FCC) emerged, the intensity of which increased as aging times rose from 6 to 12 h. Transmission electron microscope (TEM) images showed that the average precipitate size was around 10 nm in 700 °C/6 h specimens and 18 nm in 700 °C/12 h specimens. The precipitate was enriched in Ni, Al, and Ta elements and exhibited an L1₂ crystal structure. Tensile samples aged at 700 °C for 6 and 12 h exhibited recoverable strains of 1% and 2.6%, respectively, at room temperature. Digital image correlation (DIC) results for the sample aged at 700 °C for 12 h showed that two martensite variants were activated during the superelastic test. Such variants can form corresponding variant pairs (CVPs), which promote tensile deformation. The tensile sample exhibited a gradual cyclic degradation, and a large irrecoverable strain was observed after the test. This irrecoverable strain was the result of residual martensite, which was pinned by dislocations. Full article

(This article belongs to the Special Issue Feature Papers in Metallic Functional Materials)

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13 pages, 2949 KiB

Open AccessArticle

Structure, Microstructure and Magnetocaloric/Thermomagnetic Properties at the Early Sintering of MnFe(P,Si,B) Compounds

by Tvrgvn Qianbai, Hargen Yibole and Francois Guillou

Metals 2024, 14(4), 385; https://doi.org/10.3390/met14040385 - 26 Mar 2024

Viewed by 1012

Abstract

Minimizing the sintering time while ensuring high performances is an important optimization step for the preparation of magnetocaloric or thermomagnetic materials produced by powder metallurgy. Here, we study the influence of sintering time on the properties of a Mn_0.95Fe₁P_0.56Si_0.39B_0.05 compound. In contrast to former reports investigating different annealing temperatures during heat treatments of several hours or days, we pay special attention to the earliest stages of sintering. After ball-milling and powder compaction, 2 min sintering at 1100 °C is found sufficient to form the desired Fe₂P-type phase. Increasing the sintering time leads to a sharper first-order magnetic transition, a stronger latent heat, and usually to a larger isothermal entropy change, though not in all cases. As demonstrated by DSC or magnetization measurements, these parameters present dissimilar time evolutions, highlighting the existence of various underlying mechanisms. Chemical inhomogeneities are likely responsible for broadened transitions for the shortest sinterings. The development of strong latent heat requires longer sinterings than those for sharpening the magnetic transition. The microstructure may play a role as the average grain size progressively increases with the sintering time from 3.5 μm (2 min) to 30.1 μm (100 h). This systematic study has practical consequences for optimizing the preparation of MnFe(P,Si,B) compounds, but also raises intriguing questions on the influence of the microstructure and of the chemical homogeneity on magnetocaloric or thermomagnetic performances. Full article

(This article belongs to the Special Issue Feature Papers in Metallic Functional Materials)

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14 pages, 3958 KiB

Open AccessArticle

A Study of a Cryogenic CuAlMn Shape Memory Alloy

by Adelaide Nespoli, Francesca Passaretti, Davide Ninarello, Marcella Pani, Cristina Artini, Francesca Ferro and Carlo Fanciulli

Metals 2024, 14(3), 323; https://doi.org/10.3390/met14030323 - 11 Mar 2024

Viewed by 1620

Abstract

In extreme temperature environments, a newly emerging engineering application involves both the active and passive control of structures using cryogenic shape memory alloys, which are smart materials able to recover high deformation below the freezing point. With the objective of carrying out new advances in this area, the present work aims to investigate the Cu-7.5Al-13.5Mn (wt.%) shape memory alloy. Thermal, microstructural, and thermomechanical analyses of as-cast and hot-rolled specimens were performed, taking into account the effects of annealing and solubilization. It was observed that the phase transition occurs at temperatures below 120 K and changes according to the thermo-mechanical path. Specifically, hot-rolling lowers the phase transition temperature range with respect to the as-cast condition–from 34 K to 23 K for M_f, and from 89 K to 80 K for A_f. Additionally, when the annealing temperature rises, the phase transformation temperature increases as well, and the alloy loses its cryogenic features when heat treated above 473 K. Finally, loss factors of 0.06 and 0.088, which were respectively found in dynamic and static settings, validate the material’s good damping response. Full article

(This article belongs to the Special Issue Feature Papers in Metallic Functional Materials)

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15 pages, 2489 KiB

Open AccessArticle

Applied Magnetic Field Increases Magnetic Anisotropy in HDDR-Processed Nd-Fe-B Alloy

by Zachary P. Tener, Xubo Liu, Ikenna C. Nlebedim, Matthew J. Kramer, Michael A. McGuire and Michael S. Kesler

Metals 2024, 14(3), 294; https://doi.org/10.3390/met14030294 - 1 Mar 2024

Viewed by 1351

Abstract

We investigate the effect of an applied magnetic field on the entire HDDR process using a customized reactor vessel and a warm-bore superconducting magnet. We analyzed the resulting properties produced at both a 0 applied field and a 2 Tesla applied field. We show that the application of a magnetic field throughout the HDDR process results in powders that exhibit a greater level of anisotropy compared to their ambient field counterparts. Full article

(This article belongs to the Special Issue Feature Papers in Metallic Functional Materials)

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14 pages, 7656 KiB

Open AccessArticle

Cobalt Oxide-Decorated on Carbon Derived from Onion Skin Biomass for Li-Ion Storage Application

by Yunan Liu, Ting Sun, Duygu Ege and Ali Reza Kamali

Metals 2024, 14(2), 191; https://doi.org/10.3390/met14020191 - 2 Feb 2024

Cited by 2 | Viewed by 1491

Abstract

Onion waste, particularly onion skin, is a widely generated waste material, and harnessing its potential for energy storage aligns with sustainable development goals. Despite the high specific surface area exhibited by biocarbon derived from onion skin, its Li-ion storage performance is not desirable. In this study, biocarbon derived from purple onion skin serves as the substrate for accommodating cobalt oxide (Co₃O₄) through a hydrothermal method, employing Co(NO₃)₂·6H₂O at various concentrations, and with and without prior activation using KOH treatment. The resulting samples undergo comprehensive analyses, including phase, morphological, surface, and electrochemical characterizations. The Co₃O₄ decoration on activated carbon derived from onion skin, synthesized using Co(NO₃)₂·6H₂O at a concentration of 1 M, reveals a porous structure with a surface area of 702 m²/g, featuring predominant pore sizes of less than 5 nm. Significantly, the Li-ion storage performance of this sample surpasses that of alternative samples, demonstrating a remarkable reversible capacity of 451 mAh/g even after 500 cycles at an elevated current density of 2000 mAh/g. The charge transfer resistance of the sample (110.3 Ω) is found to be substantially lower than that of the sample prepared using carbonized onion skin biomass without activation. This research introduces an innovative approach leveraging onion skin waste as a template for Co₃O₄ decoration, thereby fabricating high-performance anodes for lithium-ion batteries. Full article

(This article belongs to the Special Issue Feature Papers in Metallic Functional Materials)

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10 pages, 2053 KiB

Open AccessArticle

Hydrogen Production Properties of Aluminum–Magnesium Alloy Presenting β-Phase Al₃Mg₂

by Laurent Cuzacq, Chloé Polido, Jean-François Silvain and Jean-Louis Bobet

Metals 2023, 13(11), 1868; https://doi.org/10.3390/met13111868 - 9 Nov 2023

Cited by 3 | Viewed by 2379

Abstract

In this study, aluminum–magnesium (Al-Mg) bulk porous materials were fabricated by using uniaxial hot pressing to control the porosity rate of the material over a wide range (up to 50%). The fabricated materials were analyzed by X-ray diffraction and scanning electron microscopy. The results demonstrated the appearance of intermetallic (IM) phase Al₃Mg₂, and its quantity increased with the applied pressure. In the context of the decline of global fossil fuel reserves, the revalorization of these materials by hydrogen (H₂) production was investigated. Hydrolysis of the Al-Mg materials was carried out in a simulated seawater solution (aqueous solution of sodium chloride 35 g/L). The results showed the role of the porosity rate in the H₂ production properties of the fabricated materials; the increase of porosity rate from 10% to 50% cuts the reaction time in half. Finally, the role of IM phase Al₃Mg₂ in H₂ production was highlighted through galvanic coupling. Full article

(This article belongs to the Special Issue Feature Papers in Metallic Functional Materials)

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12 pages, 4645 KiB

Open AccessFeature PaperArticle

Graphite/Epoxy-Coated Flaky FeSiCr Powders with Enhanced Microwave Absorption

by Haonan Zhang, Xichun Zhong, Jinwen Hu, Na He, Hanxing Xu, Xuefeng Liao, Qing Zhou, Zhongwu Liu and Raju V. Ramanujan

Metals 2023, 13(9), 1611; https://doi.org/10.3390/met13091611 - 18 Sep 2023

Cited by 2 | Viewed by 1698

Abstract

Flake-shaped FeSiCr (FFSC) material is expected to be a promising microwave absorbent due to its excellent magnetic properties and environmental resistance. By introducing carbon-based materials through suitable coatings, the electromagnetic parameters and energy loss can be tuned to improve the performance of FFSC. A facile solution-blending method was deployed to prepare graphite- and epoxy resin-encapsulated FFSC (FFSC@G/E) powders with a core–shell structure. FFSC@G₂₀₀₀/E showed excellent performance in the X band (8–12 GHz), a minimum reflection loss (RL_min) of −42.77 dB at a thickness of 3 mm and a maximum effective absorption bandwidth (EAB_max, RL < −10 dB) that reached 4.55 GHz at a thickness of 2.7 mm. This work provides a route for the production of novel high-performance microwave absorbers. Full article

(This article belongs to the Special Issue Feature Papers in Metallic Functional Materials)

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14 pages, 5165 KiB

Open AccessArticle

FeSiCr-Based Soft Magnetic Composites with SiO₂ Insulation Coating Prepared Using the Elemental Silicon Powder Hydrolysis Method

by Chunlong Li, Hongya Yu, Guangze Han and Zhongwu Liu

Metals 2023, 13(8), 1444; https://doi.org/10.3390/met13081444 - 11 Aug 2023

Cited by 3 | Viewed by 1521

Abstract

In this work, FeSiCr powders were coated with a SiO₂ insulation layer for soft magnetic composites (SMCs) through elemental silicon powder hydrolysis, without using any expensive precursors. The effects of the reaction temperature and ammonia concentration on the structure and performance of SMCs were investigated. Through the elemental silicon powder hydrolysis process, the formation of an FeSiCr–SiO₂ core-shell structure effectively reduced the core loss, increased resistivity, and improved the quality factor of SMCs. SMCs prepared with 0.10 mL/g ammonia concentration at 50 °C exhibited the best combination of properties, with saturation magnetization M_s = 169.40 emu/g, effective permeability μ_e = 40.46, resistivity ρ = 7.1 × 10⁶ Ω·cm, quality factor Q = 57.07 at 1 MHz, and core loss P_s = 493.3 kW/m³ at 50 mT/100 kHz. Compared to the uncoated sample, SMCs with a SiO₂ coating exhibit 23% reduction in P_s, with only 6.6% reduction in μ_e. Compared to SMCs fabricated using the traditional sol-gel method, the sample prepared through hydrolysis of elemental silicon powder has higher permeability and lower core loss. In particular, this new approach gives an effective coat solution for the mass production of high-temperature-resistant SMCs. Full article

(This article belongs to the Special Issue Feature Papers in Metallic Functional Materials)

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12 pages, 1966 KiB

Open AccessArticle

Effect of Magnetic Field and Hydrostatic Pressure on Metamagnetic Isostructural Phase Transition and Multicaloric Response of Fe₄₉Rh₅₁ Alloy

by Alexander P. Kamantsev, Abdulkarim A. Amirov, Vladislav D. Zaporozhets, Igor F. Gribanov, Aleksay V. Golovchan, Victor I. Valkov, Oksana O. Pavlukhina, Vladimir V. Sokolovskiy, Vasiliy D. Buchelnikov, Akhmed M. Aliev and Victor V. Koledov

Metals 2023, 13(5), 956; https://doi.org/10.3390/met13050956 - 15 May 2023

Cited by 5 | Viewed by 1650

Abstract

The effect of a high magnetic field up to 12 T and a high hydrostatic pressure up to 12 kbar on the stability of the metamagnetic isostructural phase transition and the multicaloric effect of Fe₄₉Rh₅₁ alloy has been studied. The phase transition temperature shifts under the magnetic field and the hydrostatic pressure on with the rates of dT_m/μ₀dH = −9.2 K/T and dT_m/dP = 3.4 K/kbar, respectively. The magnetocaloric and multicaloric (under two external fields) effects were studied via indirect method using Maxwell relations. The maximum of the entropy change is increasing toward the high temperature region from ∆S~2.5 J/(kg K) at 305 K to ∆S~2.7 J/(kg K) at 344 K under simultaneously applied magnetic field of 0.97 T and hydrostatic pressure of 12 kbar. The obtained results were explained using the first-principle calculations of Gibbs energies and the phonon spectra of the ferromagnetic and the antiferromagnetic phases. Taking into account the low concentration of antisite defects in the calculation cells allows us to reproduce the experimental dT_m/dP coefficient. Full article

(This article belongs to the Special Issue Feature Papers in Metallic Functional Materials)

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Review

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33 pages, 5606 KiB

Open AccessReview

Synthesis of Metal Nanoparticles under Microwave Irradiation: Get Much with Less Energy

by Leonid Kustov and Kseniia Vikanova

Metals 2023, 13(10), 1714; https://doi.org/10.3390/met13101714 - 8 Oct 2023

Cited by 9 | Viewed by 3916

Abstract

Microwave irradiation is widely used to intensify various chemical processes, including in the synthesis of nanomaterials. The purpose of this review is to present recent trends in the application of microwave heating for the preparation of monometallic, bimetallic, and more complicated metal nanoparticles. The advantages and drawbacks behind the use of microwave irradiation in the synthesis of unsupported and supported metal nanoparticles are summarized. Such metals as Ag, Au, Pt, Pd, Rh, Ir, Cu, Ni, Co, etc. are considered. Illustrative examples have been presented of the positive effects of microwave treatments, including the preparation of particles of different shapes and particles of immiscible metals. Full article

(This article belongs to the Special Issue Feature Papers in Metallic Functional Materials)

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