Research

Jump to: Review

32 pages, 5942 KiB

Open AccessArticle

An Extended Kolmogorov–Avrami–Ishibashi (EKAI) Model to Simulate Dynamic Characteristics of Polycrystalline-Ferroelectric-Gate Field-Effect Transistors

by Shigeki Sakai and Mitsue Takahashi

Materials 2024, 17(5), 1077; https://doi.org/10.3390/ma17051077 - 26 Feb 2024

Viewed by 913

Abstract

A physics-based model on polarization switching in ferroelectric polycrystalline films is proposed. The calculation results by the model agree well with experimental results regarding dynamic operations of ferroelectric-gate field-effect transistors (FeFETs). In the model, an angle θ for each grain in the ferroelectric [...] Read more.

A physics-based model on polarization switching in ferroelectric polycrystalline films is proposed. The calculation results by the model agree well with experimental results regarding dynamic operations of ferroelectric-gate field-effect transistors (FeFETs). In the model, an angle θ for each grain in the ferroelectric polycrystal is defined, where θ is the angle between the spontaneous polarization and the film normal direction. Under a constant electric field for a single-crystal film with θ = 0, phenomena regarding polarization domain nucleation and wall propagation are well described by the Kolmogorov–Avrami–Ishibashi theory. Since the electric fields are time-dependent in FeFET operations and the θ values are distributed in the polycrystalline film, the model in this paper forms an extended Kolmogorov–Avrami–Ishibashi (EKAI) model. Under a low electric field, the nucleation and domain propagation proceed according to thermally activated processes, meaning that switching the time scale of a grain with the angle θ is proportional to an exponential form as

e x p (c o n s t . / E_{z} c o s θ)

[

E_{z}

: the film-normal electric field]. Wide θ distribution makes the time response quite broad even on the logarithmic scale, which relates well with the broad switching time experimentally shown by FeFETs. The EKAI model is physics based and need not assume non-physical distribution functions in it. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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19 pages, 37911 KiB

Open AccessArticle

Near Net Shape Manufacturing of Sheets from Al-Cu-Li-Mg-Sc-Zr Alloy

by Barbora Kihoulou, Rostislav Králík, Lucia Bajtošová, Olexandr Grydin, Mykhailo Stolbchenko, Mirko Schaper and Miroslav Cieslar

Materials 2024, 17(3), 644; https://doi.org/10.3390/ma17030644 - 28 Jan 2024

Viewed by 575

Abstract

Thin twin-roll cast strips from a model Al-Cu-Mg-Li-Zr alloy with a small addition of Sc were prepared. A combination of a fast solidification rate and a favorable effect of Sc microalloying refines the grain size and the size of primary phase particles and [...] Read more.

Thin twin-roll cast strips from a model Al-Cu-Mg-Li-Zr alloy with a small addition of Sc were prepared. A combination of a fast solidification rate and a favorable effect of Sc microalloying refines the grain size and the size of primary phase particles and reduces eutectic cell dimensions to 10–15

μ

m. Long-term homogenization annealings used in conventionally cast materials lasting several tens of hours followed by a necessary dimension reduction through rolling/extruding could be substituted by energy and material-saving procedure. It consists of two-step short annealings at 300 °C/30 min and 450 °C/30 min, followed by the refinement and hardening of the structure using constrained groove pressing. A dense dispersion of 10–20 nm spherical

{Al}_{3} (Sc, Zr)

precipitates intensively forms during this treatment and effectively stabilizes the structure and inhibits the grain growth during subsequent solution treatment at 530 °C/30 min. Small (3%) pre-straining after quenching assures more uniform precipitation of strengthening

{Al}_{2} Cu

(

θ^{'}

),

{Al}_{2} CuMg

(

S'

), and Al₂CuLi (

T_{1}

) particles during subsequent age-hardening annealing at 180 °C/14 h. The material does not contain a directional and anisotropic structure unavoidable in rolled or extruded sheets. The proposed procedure thus represents a model near net shape processing strategy for manufacturing lightweight high-strength sheets for cryogenic applications in aeronautics. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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17 pages, 12421 KiB

Open AccessArticle

A Superhydrophobic Surface on a Superalloy Substrate with Properties of High Mechanical Strength and Self-Cleaning of Carbon Deposition

by Bingzhen Zhang, Yang Chen and Jinlong Song

Materials 2024, 17(2), 508; https://doi.org/10.3390/ma17020508 - 20 Jan 2024

Viewed by 694

Abstract

Laser processing is an efficient method for fabricating a superhydrophobic surface and has attracted much attention due to its multifunctionality. However, excessive laser processing, such as laser beam overlap and multiple scans, generates both a thick, brittle recast layer and a thin material [...] Read more.

Laser processing is an efficient method for fabricating a superhydrophobic surface and has attracted much attention due to its multifunctionality. However, excessive laser processing, such as laser beam overlap and multiple scans, generates both a thick, brittle recast layer and a thin material thickness, thereby greatly reducing the mechanical strength of the substrate. In addition, there is no report on fabricating a superhydrophobic surface on a superalloy substrate whose application includes a self-cleaning property. This work proposes the fabrication of a superhydrophobic surface on a superalloy substrate with high mechanical strength by optimizing the laser processing parameters including laser power, scanning speed, line spacing, and number of scans. We found that the microstructures required by superhydrophobicity could be constructed with a single laser scan. which could guarantee a minimal loss of the mechanical strength. The fabricated superhydrophobic surface on the superalloy substrate exhibited excellent self-cleaning of carbon deposition, showing good application potential in the aero engine field. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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12 pages, 4522 KiB

Open AccessArticle

Impact of Glass Free Volume on Femtosecond Laser-Written Nanograting Formation in Silica Glass

by Nadezhda Shchedrina, Maxime Cavillon, Julien Ari, Nadège Ollier and Matthieu Lancry

Materials 2024, 17(2), 502; https://doi.org/10.3390/ma17020502 - 20 Jan 2024

Viewed by 587

Abstract

In this study, we investigate the effects of densification through high pressure and temperature (up to 5 GPa, 1000 °C) in the making of nanogratings in pure silica glass, inscribed with femtosecond laser. The latter were monitored through retardance measurements using polarized optical [...] Read more.

In this study, we investigate the effects of densification through high pressure and temperature (up to 5 GPa, 1000 °C) in the making of nanogratings in pure silica glass, inscribed with femtosecond laser. The latter were monitored through retardance measurements using polarized optical microscopy, and their internal structure was observed under scanning electron microscopy. We reveal the difficulty in making nanogratings in densified silica glasses. Based on this observation, we propose that free volume may be a key precursor to initiate nanograting formation. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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14 pages, 13844 KiB

Open AccessArticle

Confined Layer Slip Process in Nanolaminated Ag and Two Ag/Cu Nanolaminates

by Mahshad Fani, Wu-Rong Jian, Yanqing Su and Shuozhi Xu

Materials 2024, 17(2), 501; https://doi.org/10.3390/ma17020501 - 20 Jan 2024

Cited by 1 | Viewed by 567

Abstract

The exceptional strength of nanolaminates is attributed to the influence of their fine stratification on the movement of dislocations. Through atomistic simulations, the impact of interfacial structure on the dynamics of an edge dislocation, which is compelled to move within a nanoscale layer [...] Read more.

The exceptional strength of nanolaminates is attributed to the influence of their fine stratification on the movement of dislocations. Through atomistic simulations, the impact of interfacial structure on the dynamics of an edge dislocation, which is compelled to move within a nanoscale layer of a nanolaminate, is examined for three different nanolaminates. In this study, we model confined layer slip in three structures: nanolaminated Ag and two types of Ag/Cu nanolaminates. We find that the glide motion is jerky in the presence of incoherent interfaces characterized by distinct arrays of misfit dislocations. In addition, the glide planes exhibit varying levels of resistance to dislocation motion, where planes with intersection lines that coincide with misfit dislocation lines experience greater resistance than planes without such intersection lines. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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19 pages, 765 KiB

Open AccessArticle

Dynamics of a Magnetic Polaron in an Antiferromagnet

by Kaijun Shen, Maxim F. Gelin, Kewei Sun and Yang Zhao

Materials 2024, 17(2), 469; https://doi.org/10.3390/ma17020469 - 18 Jan 2024

Viewed by 644

Abstract

The t-J model remains an indispensable construct in high-temperature superconductivity research, bridging the gap between charge dynamics and spin interactions within antiferromagnetic matrices. This study employs the multiple Davydov Ansatz method with thermo-field dynamics to dissect the zero-temperature and finite-temperature behaviors. We uncover [...] Read more.

The t-J model remains an indispensable construct in high-temperature superconductivity research, bridging the gap between charge dynamics and spin interactions within antiferromagnetic matrices. This study employs the multiple Davydov Ansatz method with thermo-field dynamics to dissect the zero-temperature and finite-temperature behaviors. We uncover the nuanced dependence of hole and spin deviation dynamics on the spin–spin coupling parameter J, revealing a thermally-activated landscape where hole mobilities and spin deviations exhibit a distinct temperature-dependent relationship. This numerically accurate thermal perspective augments our understanding of charge and spin dynamics in an antiferromagnet. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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15 pages, 8173 KiB

Open AccessArticle

Heat Capacity of Indium or Gallium Sesqui-Chalcogenides

by Květoslav Růžička, Václav Pokorný, Jan Plutnar, Iva Plutnarová, Bing Wu, Zdeněk Sofer and David Sedmidubský

Materials 2024, 17(2), 361; https://doi.org/10.3390/ma17020361 - 11 Jan 2024

Viewed by 513

Abstract

The chalcogenides of p-block elements constitute a significant category of materials with substantial potential for advancing the field of electronic and optoelectronic devices. This is attributed to their exceptional characteristics, including elevated carrier mobility and the ability to fine-tune band gaps through solid [...] Read more.

The chalcogenides of p-block elements constitute a significant category of materials with substantial potential for advancing the field of electronic and optoelectronic devices. This is attributed to their exceptional characteristics, including elevated carrier mobility and the ability to fine-tune band gaps through solid solution formation. These compounds exhibit diverse structures, encompassing both three-dimensional and two-dimensional configurations, the latter exemplified by the compound In₂Se₃. Sesqui-chalcogenides were synthesized through the direct reaction of highly pure elements within a quartz ampoule. Their single-phase composition was confirmed using X-ray diffraction, and the morphology and chemical composition were characterized using scanning electron microscopy. The compositions of all six materials were also confirmed using X-ray photoelectron spectroscopy and Raman spectroscopy. This investigation delves into the thermodynamic properties of indium and gallium sesqui-chalcogenides. It involves low-temperature heat capacity measurements to evaluate standard entropies and Tian–Calvet calorimetry to elucidate the temperature dependence of heat capacity beyond the reference temperature of 298.15 K, as well as the enthalpy of formation assessed from DFT calculations. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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22 pages, 4919 KiB

Open AccessArticle

Conducting and Magnetic Hybrid Polypyrrole/Nickel Composites and Their Application in Magnetorheology

by Marek Jurča, Jarmila Vilčáková, Natalia E. Kazantseva, Andrei Munteanu, Lenka Munteanu, Michal Sedlačík, Jaroslav Stejskal, Miroslava Trchová and Jan Prokeš

Materials 2024, 17(1), 151; https://doi.org/10.3390/ma17010151 - 27 Dec 2023

Cited by 1 | Viewed by 557

Abstract

Hybrid organic/inorganic conducting and magnetic composites of core–shell type have been prepared by in-situ coating of nickel microparticles with polypyrrole. Three series of syntheses have been made. In the first, pyrrole was oxidised with ammonium peroxydisulfate in water in the presence of various [...] Read more.

Hybrid organic/inorganic conducting and magnetic composites of core–shell type have been prepared by in-situ coating of nickel microparticles with polypyrrole. Three series of syntheses have been made. In the first, pyrrole was oxidised with ammonium peroxydisulfate in water in the presence of various amounts of nickel and the composites contained up to 83 wt% of this metal. The second series used 0.1 M sulfuric acid as a reaction medium. Finally, the composites with polypyrrole nanotubes were prepared in water in the presence of structure-guiding methyl orange dye. The nanotubes have always been accompanied by the globular morphology. FTIR and Raman spectroscopies confirmed the formation of polypyrrole. The resistivity of composite powders of the order of tens to hundreds Ω cm was monitored as a function of pressure up to 10 MPa. The resistivity of composites slightly increased with increasing content of nickel. This apparent paradox is explained by the coating of nickel particles with polypyrrole, which prevents their contact and subsequent generation of metallic conducting pathways. Electrical properties were practically independent of the way of composite preparation or nickel content and were controlled by the polypyrrole phase. On the contrary, magnetic properties were determined exclusively by nickel content. The composites were used as a solid phase to prepare a magnetorheological fluid. The test showed better performance when compared with a different nickel system reported earlier. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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11 pages, 371 KiB

Open AccessArticle

Multiferroic Properties of Co, Ru, and La Ion Doped KBiFe₂O₅

by Angel Apostolov, Iliana Apostolova and Julia Wesselinowa

Materials 2024, 17(1), 1; https://doi.org/10.3390/ma17010001 - 19 Dec 2023

Cited by 1 | Viewed by 621

Abstract

The magnetic, electric, dielectric, and optical (band gap) properties of ion doped multiferroic KBiFe

_{2}

O

_{5}

(KBFO) have been systematically investigated utilizing a microscopic model and the Green’s function theory. Doping with Co at the Fe site and Ru at the Bi [...] Read more.

The magnetic, electric, dielectric, and optical (band gap) properties of ion doped multiferroic KBiFe

_{2}

O

_{5}

(KBFO) have been systematically investigated utilizing a microscopic model and the Green’s function theory. Doping with Co at the Fe site and Ru at the Bi site induces changes in magnetization, coercive field, and band gap energy. Specifically, an increase in magnetization is observed, while the coercive field and band gap energy decrease. This behavior is attributed to the distinct ionic radii of the doped and host ions, leading to alterations in the exchange interaction constants. The temperature dependence of the polarization P reveals a distinctive kink at the Neel temperature

T_{N}

, which shifts to higher temperatures with an increase in the applied magnetic field h. Furthermore, doping with Ru and La leads to an increase in polarization. The temperature dependence of the dielectric constant exhibits two peaks at the Neel temperature

T_{N}

and the Curie temperature

T_{C}

. Notably, these peaks diminish with increasing frequency. Additionally, the dielectric constant demonstrates a decrease with the rise in the applied magnetic field h. This study sheds light on the intricate interplay between ion doping, structural modifications, and multifunctional properties in KBFO, offering valuable insights into the underlying mechanisms governing its behavior across various physical domains. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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11 pages, 1448 KiB

Open AccessArticle

Study of Elastic and Structural Properties of BaFe₂As₂ Ultrathin Film Using Picosecond Ultrasonics

by Di Cheng, Boqun Song, Jong-Hoon Kang, Chris Sundahl, Anthony L. Edgeton, Liang Luo, Joong-Mok Park, Yesusa G. Collantes, Eric E. Hellstrom, Martin Mootz, Ilias E. Perakis, Chang-Beom Eom and Jigang Wang

Materials 2023, 16(21), 7031; https://doi.org/10.3390/ma16217031 - 03 Nov 2023

Viewed by 825

Abstract

We obtain the through-thickness elastic stiffness coefficient (C₃₃) in nominal 9 nm and 60 nm BaFe₂As₂ (Ba-122) thin films by using picosecond ultrasonics. Particularly, we reveal the increase in elastic stiffness as film thickness decreases from bulk [...] Read more.

We obtain the through-thickness elastic stiffness coefficient (C₃₃) in nominal 9 nm and 60 nm BaFe₂As₂ (Ba-122) thin films by using picosecond ultrasonics. Particularly, we reveal the increase in elastic stiffness as film thickness decreases from bulk value down to 9 nm, which we attribute to the increase in intrinsic strain near the film-substrate interface. Our density functional theory (DFT) calculations reproduce the observed acoustic oscillation frequencies well. In addition, temperature dependence of longitudinal acoustic (LA) phonon mode frequency for 9 nm Ba-122 thin film is reported. The frequency change is attributed to the change in Ba-122 orthorhombicity

(a - b) / (a + b)

. This conclusion can be corroborated by our previous ultrafast ellipticity measurements in 9 nm Ba-122 thin film, which exhibit strong temperature dependence and indicate the structural phase transition temperature T_s. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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12 pages, 5073 KiB

Open AccessFeature PaperArticle

Microstructural and Mechanical Characterization of Colloidal Processed WC/(W5Vol%Ni) via Spark Plasma Sintering

by Ahmed-Ameur Zegai, Hossein Besharatloo, Pablo Ortega, Boubekeur Djerdjare, Begoña Ferrari and Antonio Javier Sanchez-Herencia

Materials 2023, 16(13), 4584; https://doi.org/10.3390/ma16134584 - 25 Jun 2023

Viewed by 835

Abstract

This study investigates the sintering behaviour and properties of WC-based composites in which WC was mixed with W5vol%Ni in concentrations of 10vol% and 20vol%. Colloidal processing in water and spark plasma sintering were employed to disperse the WC particles and facilitate sintering. The [...] Read more.

This study investigates the sintering behaviour and properties of WC-based composites in which WC was mixed with W5vol%Ni in concentrations of 10vol% and 20vol%. Colloidal processing in water and spark plasma sintering were employed to disperse the WC particles and facilitate sintering. The addition of W5vol%Ni improved the sintering process, as evident from a lower onset temperature of shrinkage determined through dilatometric studies. All samples exhibited the formation of tungsten monocarbide (W₂C), with a more pronounced presence in the WC/20(W5vol%Ni) composite. Sintering reached its maximum rate at 1550 °C and was completed at 1600 °C, resulting in a final density exceeding 99.8%. X-ray diffraction analysis confirmed the detection of WC and W₂C phases after sintering. The observed WC content was higher than expected, which may be attributed to carbon diffusion during the process. Macro-scale mechanical characterisations revealed that the WC/10(W5vol%Ni) composite exhibited a hardness of 18.9 GPa, while the WC/20(W5vol%Ni) composite demonstrated a hardness of 18.3 GPa. Increasing the W5vol%Ni binder content caused a decrease in mechanical properties due to the formation of W₂C phases. This study provides valuable insights into the sintering behavior and properties of WC/W5vol%Ni composites, offering potential applications in extreme environments. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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11 pages, 6706 KiB

Open AccessArticle

Substrate-Induced Changes on the Optical Properties of Single-Layer WS₂

by F. D. V. Araujo, F. W. N. Silva, T. Zhang, C. Zhou, Zhong Lin, Nestor Perea-Lopez, Samuel F. Rodrigues, Mauricio Terrones, Antônio Gomes Souza Filho, R. S. Alencar and Bartolomeu C. Viana

Materials 2023, 16(7), 2591; https://doi.org/10.3390/ma16072591 - 24 Mar 2023

Viewed by 1465

Abstract

Among the most studied semiconducting transition metal dichalcogenides (TMDCs), WS

_{2}

showed several advantages in comparison to their counterparts, such as a higher quantum yield, which is an important feature for quantum emission and lasing purposes. We studied transferred monolayers of WS

_{2}

[...] Read more.

Among the most studied semiconducting transition metal dichalcogenides (TMDCs), WS

_{2}

showed several advantages in comparison to their counterparts, such as a higher quantum yield, which is an important feature for quantum emission and lasing purposes. We studied transferred monolayers of WS

_{2}

on a drilled Si

_{3}

N

_{4}

substrate in order to have insights about on how such heterostructure behaves from the Raman and photoluminescence (PL) measurements point of view. Our experimental findings showed that the Si

_{3}

N

_{4}

substrate influences the optical properties of single-layer WS

_{2}

. Beyond that, seeking to shed light on the causes of the PL quenching observed experimentally, we developed density functional theory (DFT) based calculations to study the thermodynamic stability of the heterojunction through quantum molecular dynamics (QMD) simulations as well as the electronic alignment of the energy levels in both materials. Our analysis showed that along with strain, a charge transfer mechanism plays an important role for the PL decrease. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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10 pages, 3446 KiB

Open AccessArticle

Synthesis and Crystal Structure of the Zintl Phases NaSrSb, NaBaSb and NaEuSb

by Yi Wang and Svilen Bobev

Materials 2023, 16(4), 1428; https://doi.org/10.3390/ma16041428 - 08 Feb 2023

Cited by 4 | Viewed by 1491

Abstract

This work details the synthesis and the crystal structures of the ternary compounds NaSrSb, NaBaSb and NaEuSb. They are isostructural and adopt the hexagonal ZrNiAl-type structure (space group P

\bar{6}

2m; Pearson code hP9). The structure determination in all [...] Read more.

This work details the synthesis and the crystal structures of the ternary compounds NaSrSb, NaBaSb and NaEuSb. They are isostructural and adopt the hexagonal ZrNiAl-type structure (space group P

\bar{6}

2m; Pearson code hP9). The structure determination in all three cases was performed using single-crystal X-ray diffraction methods. The structure features isolated Sb^3– anions arranged in layers stacked along the crystallographic c-axis. In the interstices, alkali and alkaline-earth metal cations are found in tetrahedral and square pyramidal coordination environments, respectively. The formal partitioning of the valence electrons adheres to the valence rules, i.e., Na⁺Sr²⁺Sb^3–, Na⁺Ba²⁺Sb^3– and Na⁺Eu²⁺Sb^3– can be considered as Zintl phases with intrinsic semiconductor behavior. Electronic band structure calculations conducted for NaBaSb are consistent with this notion and show a direct gap of approx. 0.9 eV. Additionally, the calculations hint at possible inverted Dirac cones, a feature that is reminiscent of topological quantum materials. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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Review

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28 pages, 35152 KiB

Open AccessEditor’s ChoiceReview

The Role of Lithium in the Aging Precipitation Process of Al-Zn-Mg-Cu Alloys and Its Effect on the Properties

by Jing-Ran Sun, Bai-Xin Dong, Hong-Yu Yang, Shi-Li Shu, Feng Qiu, Qi-Chuan Jiang and Lai-Chang Zhang

Materials 2023, 16(13), 4750; https://doi.org/10.3390/ma16134750 - 30 Jun 2023

Viewed by 1102

Abstract

It is well known that the development of lightweight alloys with improved comprehensive performance and application value are the future development directions for the ultra-high-strength 7xxx series Al-Zn-Mg-Cu alloys used in the aircraft field. As the lightest metal element in nature, lithium (Li) [...] Read more.

It is well known that the development of lightweight alloys with improved comprehensive performance and application value are the future development directions for the ultra-high-strength 7xxx series Al-Zn-Mg-Cu alloys used in the aircraft field. As the lightest metal element in nature, lithium (Li) has outstanding advantages in reducing the density and increasing the elastic modulus in aluminum alloys, so Al-Zn-Mg-Cu alloys containing Li have gained widespread attention. Furthermore, since the Al-Zn-Mg-Cu alloy is usually strengthened by aging treatment, it is crucial to understand how Li addition affects its aging precipitation process. As such, in this article, the effects and mechanism of Li on the aging precipitation behavior and the impact of Li content on the aging precipitation phase of Al-Zn-Mg-Cu alloys are briefly reviewed, and the influence of Li on the service properties, including mechanical properties, wear resistance, and fatigue resistance, of Al-Zn-Mg-Cu alloys are explained. In addition, the corresponding development prospects and challenges of the Al-Zn-Mg-Cu-Li alloy are also proposed. This review is helpful to further understand the role of Li in Al-Zn-Mg-Cu alloys and provides a reference for the development of high-strength aluminum alloys containing Li with good comprehensive properties. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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12 pages, 2745 KiB

Open AccessReview

Low Temperature Nitriding of Metal Alloys for Surface Mechanical Performance

by Michel Drouet and Eric Le Bourhis

Materials 2023, 16(13), 4704; https://doi.org/10.3390/ma16134704 - 29 Jun 2023

Cited by 2 | Viewed by 1379

Abstract

Metallic alloys are, by essence, ductile and stiff and can support loads without sudden rupture. This ductility becomes a disadvantage when applications require wear resistance. In this case, the hardening of the surface is required while retaining a core performance. Here, nitriding at [...] Read more.

Metallic alloys are, by essence, ductile and stiff and can support loads without sudden rupture. This ductility becomes a disadvantage when applications require wear resistance. In this case, the hardening of the surface is required while retaining a core performance. Here, nitriding at low temperatures has proven to be beneficial and has potential. In fact, any phase transitions or unwanted compound precipitations that occur at higher temperatures have to be avoided as they would have a deleterious effect on the chemical homogeneity and mechanical properties. The present contribution summarizes the achievements made with such treatments on metallic alloys. We considered the most popular treatments, namely plasma, implantation, and gas nitridings. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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20 pages, 6423 KiB

Open AccessReview

Progress on the Fabrication of Superconducting Wires and Tapes via Hot Isostatic Pressing

by Zhenyu Lei, Chao Yao, Wenwen Guo, Dongliang Wang and Yanwei Ma

Materials 2023, 16(5), 1786; https://doi.org/10.3390/ma16051786 - 22 Feb 2023

Cited by 1 | Viewed by 1999

Abstract

Fabrication of high-performance superconducting wires and tapes is essential for large-scale applications of superconducting materials. The powder-in-tube (PIT) method involves a series of cold processes and heat treatments and has been widely used for fabricating BSCCO, MgB₂, and iron-based superconducting wires. [...] Read more.

Fabrication of high-performance superconducting wires and tapes is essential for large-scale applications of superconducting materials. The powder-in-tube (PIT) method involves a series of cold processes and heat treatments and has been widely used for fabricating BSCCO, MgB₂, and iron-based superconducting wires. The densification of the superconducting core is limited by traditional heat treatment under atmospheric pressure. The low density of the superconducting core and a large number of pores and cracks are the main factors limiting the current-carrying performance of PIT wires. Therefore, to improve the transport critical current density of the wires, it is essential to densify the superconducting core and eliminate pores and cracks to enhance grain connectivity. Hot isostatic pressing (HIP) sintering was employed to improve the mass density of superconducting wires and tapes. In this paper, we review the development and application of the HIP process in the manufacturing of BSCCO, MgB₂, and iron-based superconducting wires and tapes. The development of HIP parameters and the performance of different wires and tapes are reviewed. Finally, we discuss the advantages and prospects of the HIP process for the fabrication of superconducting wires and tapes. Full article

(This article belongs to the Special Issue The 15th Anniversary of Materials—Recent Advances in Materials Physics)

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