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Special Issue "Intermetallic Alloys: Fabrication, Properties and Applications 2017"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (30 May 2018)

Special Issue Editor

Guest Editor
Prof. Dr. Louisa Meshi

Department of Materials Engineering, Ben Gurion University of the Negev, Beer Sheva, Israel
Website | E-Mail

Special Issue Information

Dear Colleagues,

Our world advances rapidly. New materials are needed to face novel applications. In the past, new materials were found mostly by applying a "trial and error" approach. The need for generalization and a quicker path towards discoveries pushed governments all over the world to sponsor the so-called "Materials Genome Initiative", i.e., an initiative to identify potential materials with unique properties through systematization of knowledge and the combination of theory and experiment. Thus, new theories and rules are being developed in order to predict the functional materials of tomorrow. Most of the research points to intermetallics. The class of intermetallics possesses an excellent combination of high strength, low density and good corrosion resistance, especially at higher temperatures and in severe environments. Some of intermetallides also exhibit interesting electric–magnetic properties (such as shape memory, thermo-electricity, magnetic ordering, superconductivity, and many others). However, these materials have some drawbacks, such as combination of high strength and poor ductility and lack of industrialized manufacturing and processing technologies. Many specialists all over the world address these drawbacks. Examples of such efforts are iron aluminides and titanium aluminides, which are prominent lightweight, creep- and oxidation-resistant materials, used today in aircraft engines, raising efficiency and reducing weight and CO2 and NOx emissions. Another difficulty encountered in the research of intermetallics is characterization. Potential applications usually require intermetallides to be embedded in more ductile metallic matrices. In such cases, intermetallics appear as small precipitates in multiphase alloys. Characterization of the atomic structure of such nano-sized precipitates is a challenge in of itself. The current Special Issue, "Intermetallic Alloys: Fabrication, Properties and Applications" invites researchers working in all the listed topics to publish their work. Both theoretical and experimental research, review articles, and novel results are welcome. 

Prof. Dr. Louisa Meshi
Guest Editor

Manuscript Submission Information

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Keywords

  • Intermetallics
  • Alluminides
  • TEM
  • SEM
  • XRD
  • Characterization
  • Crystal structure
  • Microstructure
  • Sintering
  • Cast
  • Wrought
  • Mechanical properties
  • Magnetic properties
  • Manufacturing
  • DFT
  • Phase diagram
  • Metallurgy
  • Light-weight alloys
  • Refractory

Published Papers (6 papers)

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Research

Open AccessArticle Elasto-Plastic Mechanical Properties and Failure Mechanism of Innovative Ti-(SiCf/Al3Ti) Laminated Composites for Sphere-Plane Contact at the Early Stage of Penetration Process
Materials 2018, 11(7), 1152; https://doi.org/10.3390/ma11071152
Received: 24 May 2018 / Revised: 29 June 2018 / Accepted: 2 July 2018 / Published: 6 July 2018
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Abstract
A novel silicon carbide (SiC) continuous ceramic fiber-reinforced (CCFR) Ti/Al3Ti Metal-Intermetallic-Laminate (MIL) composite was fabricated. A high-efficiency semi-analytical model was proposed based on the numerical equivalent inclusion method (NEIM) for analyzing the small-strain elasto-plastic contact in the early stage of the
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A novel silicon carbide (SiC) continuous ceramic fiber-reinforced (CCFR) Ti/Al3Ti Metal-Intermetallic-Laminate (MIL) composite was fabricated. A high-efficiency semi-analytical model was proposed based on the numerical equivalent inclusion method (NEIM) for analyzing the small-strain elasto-plastic contact in the early stage of the penetration process. The microstructure and interface features were characterized by the scanning electron microscopy (SEM). Quasi-static compression tests were performed to determine the contact response and validate the proposed model. A group of in-depth parametric studies were carried out to quantify the influence of the microstructure. The comparison between results under the sphere-plane and plane-plane contact load indicates that, under the first sphere-plane, the compressive strength and failure strain are both lower and the SiC reinforcement effect on strength is very clear while the effect on ductility is not clear. The maximum plastic strain concentration (MPSC) in the Al3Ti layer is closest to the upper boundary of the central SiC fiber and then extends along the depth direction as the load increases, which are also the locations where cracks may initiate and extend. Moreover, the CCFR-MIL composite shows better mechanical properties when the center distance between adjacent SiC fibers is four times the fiber diameter and the volume fraction of Ti is 40%. Full article
(This article belongs to the Special Issue Intermetallic Alloys: Fabrication, Properties and Applications 2017)
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Graphical abstract

Open AccessFeature PaperArticle Improved Formability of Mg-AZ80 Alloy under a High Strain Rate in Expanding-Ring Experiments
Materials 2018, 11(2), 329; https://doi.org/10.3390/ma11020329
Received: 15 January 2018 / Revised: 10 February 2018 / Accepted: 14 February 2018 / Published: 24 February 2018
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Abstract
Magnesium alloys offer a favored alternative to steels and aluminum alloys due to their low density and relatively high specific strength. Their application potentials are, however, impeded by poor formability at room temperature. In the current work, improved formability for the commercial magnesium
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Magnesium alloys offer a favored alternative to steels and aluminum alloys due to their low density and relatively high specific strength. Their application potentials are, however, impeded by poor formability at room temperature. In the current work, improved formability for the commercial magnesium AZ80 alloy was attained through the application of the high-rate electro-magnetic forming (EMF) technique. With the EMF system, elongation of 0.2 was achieved while only 0.11 is obtained through quasistatic loading. Systematic microstructural and textural investigations prior, during and post deformation under high strain-rate experiments were carried out using electron back-scattered diffraction (EBSD) and other microscopic techniques. The analysis indicates that enhanced elongation is achieved as a result of the combination of deformation, comprising basal and non-basal slip systems, twinning and dynamic recrystallization. An adopted EMF-forming technique is tested which results in enhanced elongation without failure and a higher degree of dynamically annealed microstructure. Full article
(This article belongs to the Special Issue Intermetallic Alloys: Fabrication, Properties and Applications 2017)
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Open AccessArticle Radiation Resistance of the U(Al, Si)3 Alloy: Ion-Induced Disordering
Materials 2018, 11(2), 228; https://doi.org/10.3390/ma11020228
Received: 17 January 2018 / Revised: 28 January 2018 / Accepted: 31 January 2018 / Published: 2 February 2018
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Abstract
During the exploitation of nuclear reactors, various U-Al based ternary intermetallides are formed in the fuel-cladding interaction layer. Structure and physical properties of these intermetallides determine the radiation resistance of cladding and, ultimately, the reliability and lifetime of the nuclear reactor. In current
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During the exploitation of nuclear reactors, various U-Al based ternary intermetallides are formed in the fuel-cladding interaction layer. Structure and physical properties of these intermetallides determine the radiation resistance of cladding and, ultimately, the reliability and lifetime of the nuclear reactor. In current research, U(Al, Si)3 composition was studied as a potential constituent of an interaction layer. Phase content of the alloy of an interest was ordered U(Al, Si)3, structure of which was reported earlier, and pure Al (constituting less than 20 vol % of the alloy). This alloy was investigated prior and after the irradiation performed by Ar ions at 30 keV. The irradiation was performed on the transmission electron microscopy (TEM, JEOL, Japan) samples, characterized before and after the irradiation process. Irradiation induced disorder accompanied by stress relief. Furthermore, it was found that there is a dose threshold for disordering of the crystalline matter in the irradiated region. Irradiation at doses equal or higher than this threshold resulted in almost solely disordered phase. Using the program “Stopping and Range of Ions in Matter” (SRIM), the parameters of penetration of Ar ions into the irradiated samples were estimated. Based on these estimations, the dose threshold for ion-induced disordering of the studied material was assessed. Full article
(This article belongs to the Special Issue Intermetallic Alloys: Fabrication, Properties and Applications 2017)
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Open AccessArticle Characterization of an Additive Manufactured TiAl Alloy—Steel Joint Produced by Electron Beam Welding
Materials 2018, 11(1), 149; https://doi.org/10.3390/ma11010149
Received: 22 December 2017 / Revised: 11 January 2018 / Accepted: 15 January 2018 / Published: 17 January 2018
Cited by 3 | PDF Full-text (4873 KB) | HTML Full-text | XML Full-text
Abstract
In this work, the characterization of the assembly of a steel shaft into a γ-TiAl part for turbocharger application, obtained using Electron Beam Welding (EBW) technology with a Ni-based filler, was carried out. The Ti-48Al-2Nb-0.7Cr-0.3Si (at %) alloy part was produced by Electron
[...] Read more.
In this work, the characterization of the assembly of a steel shaft into a γ-TiAl part for turbocharger application, obtained using Electron Beam Welding (EBW) technology with a Ni-based filler, was carried out. The Ti-48Al-2Nb-0.7Cr-0.3Si (at %) alloy part was produced by Electron Beam Melting (EBM). This additive manufacturing technology allows the production of a lightweight part with complex shapes. The replacement of Nickel-based superalloys with TiAl alloys in turbocharger automotive applications will lead to an improvement of the engine performance and a substantial reduction in fuel consumption and emission. The welding process allows a promising joint to be obtained, not affecting the TiAl microstructure. Nevertheless, it causes the formation of diffusive layers between the Ni-based filler and both steel and TiAl, with the latter side being characterized by a very complex microstructure, which was fully characterized in this paper by means of Scanning Electron Microscopy, Energy Dispersive X-ray Spectroscopy, and nanoindentation. The diffusive interface has a thickness of about 6 µm, and it is composed of several layers. Specifically, from the TiAl alloy side, we find a layer of Ti3Al followed by Al3NiTi2 and AlNi2Ti. Subsequently Ni becomes more predominant, with a first layer characterized by abundant carbide/boride precipitation, and a second layer characterized by Si-enrichment. Then, the chemical composition of the Ni-based filler is gradually reached. Full article
(This article belongs to the Special Issue Intermetallic Alloys: Fabrication, Properties and Applications 2017)
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Open AccessArticle Largest Magnetic Moments in the Half-Heusler Alloys XCrZ (X = Li, K, Rb, Cs; Z = S, Se, Te): A First-Principles Study
Materials 2017, 10(9), 1078; https://doi.org/10.3390/ma10091078
Received: 7 August 2017 / Revised: 11 September 2017 / Accepted: 12 September 2017 / Published: 14 September 2017
Cited by 5 | PDF Full-text (11004 KB) | HTML Full-text | XML Full-text
Abstract
A recent theoretical work indicates that intermetallic materials LiMnZ (Z = N, P) with a half-Heusler structure exhibit half-metallic (HM) behaviors at their strained lattice constants, and the magnetic moments of these alloys are expected to reach as high as 5 μB
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A recent theoretical work indicates that intermetallic materials LiMnZ (Z = N, P) with a half-Heusler structure exhibit half-metallic (HM) behaviors at their strained lattice constants, and the magnetic moments of these alloys are expected to reach as high as 5 μB per formula unit. (Damewood et al. Phys. Rev. B 2015, 91, 064409). This work inspired us to find new Heusler-based half-metals with the largest magnetic moment. With the help of the first-principles calculation, we reveal that XCrZ (X = K, Rb, Cs; Z = S, Se, Te) alloys show a robust, half-metallic nature with a large magnetic moment of 5 μB at their equilibrium and strained lattice constants in their most stable phases, while the excellent HM nature of LiCrZ (Z = S, Se, Te) alloys can be observed in one of their metastable phases. Moreover, the effects of uniform strain in LiCrZ (Z = S, Se, Te) alloys in type II arrangement have also been discussed. Full article
(This article belongs to the Special Issue Intermetallic Alloys: Fabrication, Properties and Applications 2017)
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Open AccessArticle Accessing Colony Boundary Strengthening of Fully Lamellar TiAl Alloys via Micromechanical Modeling
Materials 2017, 10(8), 896; https://doi.org/10.3390/ma10080896
Received: 26 June 2017 / Revised: 27 July 2017 / Accepted: 31 July 2017 / Published: 3 August 2017
Cited by 2 | PDF Full-text (4110 KB) | HTML Full-text | XML Full-text
Abstract
In this article, we present a strategy to decouple the relative influences of colony, domain and lamella boundary strengthening in fully lamellar titanium aluminide alloys, using a physics-based crystal plasticity modeling strategy. While lamella and domain boundary strengthening can be isolated in experiments
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In this article, we present a strategy to decouple the relative influences of colony, domain and lamella boundary strengthening in fully lamellar titanium aluminide alloys, using a physics-based crystal plasticity modeling strategy. While lamella and domain boundary strengthening can be isolated in experiments using polysynthetically twinned crystals or mircomechanical testing, colony boundary strengthening can only be investigated in specimens in which all three strengthening mechanisms act simultaneously. Thus, isolating the colony boundary strengthening Hall–Petch coefficient K C experimentally requires a sufficient number of specimens with different colony sizes λ C but constant lamella thickness λ L and domain size λ D , difficult to produce even with sophisticated alloying techniques. The here presented crystal plasticity model enables identification of the colony boundary strengthening coefficient K C as a function of lamella thickness λ L . The constitutive description is based on the model of a polysynthetically twinned crystal which is adopted to a representative volume element of a fully lamellar microstructure. In order to capture the micro yield and subsequent micro hardening in weakly oriented colonies prior to macroscopic yield, the hardening relations of the adopted model are revised and calibrated against experiments with polysynthetically twinned crystals for plastic strains up to 15%. Full article
(This article belongs to the Special Issue Intermetallic Alloys: Fabrication, Properties and Applications 2017)
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