Intermetallic Compound (Volume II)

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Crystalline Metals and Alloys".

Deadline for manuscript submissions: closed (31 July 2023) | Viewed by 34679

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Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Wroclaw, Poland
Interests: fabrication of intermetallic compounds with specific magnetic properties via the arc melting method; measurements of magnetic properties; measurements and study of the magnetization; magnetocrystalline anisotropy; magnetocaloric effect of intermetallic compounds
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Special Issue Information

Dear Colleagues,

 

In modern society, the applications of new functional materials are diverse and countless. Intermetallics, namely, compounds formed by two or more metallic elements, are among the various novel and significant materials developments. Intermetallics have received considerable attention owing to their potential for various applications, such as permanent magnets, magneto-optical recording media, hydrogen storage and magnetocaloric materials, turbine blades, and in microelectronics. With a favorable combination of high strength, low density, and good corrosion resistance, intermetallics are specifically suited for applications at high temperatures and in adverse environments. They can also display desirable magnetic, superconducting, and chemical properties due to their strong internal order and mixed metallic and covalent or ionic bonding, respectively.

We invite researchers to contribute to this Special Issue on “Intermetallic Compound (Volume II)”, which is intended to serve as a unique multidisciplinary forum covering broad aspects of the science, technology, and application of intermetallic compounds.

Potential topics include but are not limited to:

- Synthesis of intermetallic compounds;

- Characteristics of structural properties;

- Type of intermetallic compounds;

- Unique properties;

- Applications.

Dr. Jacek Ćwik
Guest Editor

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Keywords

  • Functional alloys
  • High-entropy alloys
  • Shape–memory alloys
  • Magnetic properties
  • Thermal properties
  • Thermodynamic properties
  • Grain boundary
  • Superconducting

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Published Papers (17 papers)

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13 pages, 10904 KiB  
Article
Effect of High-Energy Ball Milling in Ternary Material System of (Mg-Sn-Na)
by Halit Sübütay and İlyas Şavklıyıldız
Crystals 2023, 13(8), 1230; https://doi.org/10.3390/cryst13081230 - 9 Aug 2023
Cited by 5 | Viewed by 1390
Abstract
In this study, the nature of the ball-milling mechanism in a ternary materials system (Mg-6Sn-1Na) is investigated for proper mechanical alloying. An identical powder mixture for this material system is exposed to different milling durations for a suitable mixture. First, the platelet structure [...] Read more.
In this study, the nature of the ball-milling mechanism in a ternary materials system (Mg-6Sn-1Na) is investigated for proper mechanical alloying. An identical powder mixture for this material system is exposed to different milling durations for a suitable mixture. First, the platelet structure formation is observed on particles with increasing milling duration, mainly formed in <200> direction of the hexagonal crystal structure of the Mg matrix. Then, the flake structure with texture formation is broken into smaller spherical particles with further ball milling up to 12 h. According to EDS analysis, the secondary phases in the Mg matrix are homogenously distributed with a 12-h milling duration which advises a proper mixture in this material system. The solid solution formation is triggered with an 8-h milling duration according to XRD analysis on 101 reflections. Conventional sintering is performed at 350 °C in 2 h for each sample. In bulk samples, XRD data reveal that secondary phases (Mg2Sn) with island-like structures are formed on the Mg matrix for a milling duration of up to 8 h. These bigger secondary phases are mainly constituted as Mg2Sn intermetallic forms, which have a negative effect on physical and mechanical properties due to a mismatch in the grain boundary formation. However, the homogenous distribution of secondary phases with a smaller particle size distribution, acquired with 12 h milling time, provides the highest density, modulus of elasticity, and hardness values for this ternary materials system. The ternary materials produced with the 12-h ball-milling process provide an improvement of about 117% in hardness value compared with the cast form. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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11 pages, 3937 KiB  
Article
Room and Elevated Temperature Sliding Friction and Wear Behavior of Al0.3CoFeCrNi and Al0.3CuFeCrNi2 High Entropy Alloys
by Dheyaa F. Kadhim, Manindra V. Koricherla and Thomas W. Scharf
Crystals 2023, 13(4), 609; https://doi.org/10.3390/cryst13040609 - 2 Apr 2023
Cited by 3 | Viewed by 1773
Abstract
In this study, processing–structure–property relations were systematically investigated at room and elevated temperatures for two FCC Al0.3CoFeCrNi and Al0.3CuFeCrNi2 high-entropy alloys (HEAs), also known as complex concentrated alloys (CCAs), prepared by conventional arc-melting. It was determined that both [...] Read more.
In this study, processing–structure–property relations were systematically investigated at room and elevated temperatures for two FCC Al0.3CoFeCrNi and Al0.3CuFeCrNi2 high-entropy alloys (HEAs), also known as complex concentrated alloys (CCAs), prepared by conventional arc-melting. It was determined that both alloys exhibit FCC single-phase solid solution structure. Micro-indentation and sliding wear tests were performed to study the hardness and tribological behavior and mechanisms at room and elevated temperatures. During room-temperature sliding, both alloys exhibit similar friction behavior, with an average steady-state coefficient of friction (COF) of ~0.8. Upon increasing sliding temperatures to 300 °C, the average COF decreased to a lowest value of ~0.3 for Al0.3CuFeCrNi2. Mechanistic wear studies showed this was due to the low interfacial shear strength tribofilms formed inside the wear tracks. Raman spectroscopy and energy dispersive spectroscopy determined the tribofilms were predominantly composed of binary oxides and multi-element solid solution oxides. While the tribofilms at elevated temperatures lowered the COF values, the respective wear rates in both alloys were higher compared to room-temperature sliding, due to thermal softening during 300 °C sliding. Thus, these single FCC-phase HEAs provide no further benefit in wear resistance at elevated temperatures, and likely will have similar implications for other single FCC-phase HEAs. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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11 pages, 2492 KiB  
Article
The Effect of Cr Additive on the Mechanical Properties of Ti-Al Intermetallics by First-Principles Calculations
by Hui Wang, Fuyong Su and Zhi Wen
Crystals 2023, 13(3), 488; https://doi.org/10.3390/cryst13030488 - 11 Mar 2023
Cited by 2 | Viewed by 1521
Abstract
The structure, elastic properties and electronic structure of Ti-Al intermetallics including Ti3Al (space group P63/mmc), TiAl (space group I4/mmm) and TiAl3 (space group P4/mmm) are systematically studied by first-principles calculations. The results show that Ti-Al intermetallics can exist stably whether [...] Read more.
The structure, elastic properties and electronic structure of Ti-Al intermetallics including Ti3Al (space group P63/mmc), TiAl (space group I4/mmm) and TiAl3 (space group P4/mmm) are systematically studied by first-principles calculations. The results show that Ti-Al intermetallics can exist stably whether Cr replaces Ti or Al. The ductility of the alloy cannot be improved when Ti is replaced in Cr-doped TiAl and TiAl3. However, when it replaces Al, the alloy has better ductility. In Ti3Al, the ductility can be improved regardless of whether Cr replaces Ti or Al, and the effect is better when it replaces Al. The bond in Ti-Al intermetallics is mainly a Ti-Ti metal bond. The metal bond between Ti-Ti is strengthened and a solid metal bond is formed between Cr and Ti, inducing a better ductility of the material, after Cr replaces Al in Ti-Al intermetallics. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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10 pages, 404 KiB  
Article
Ginzburg–Landau Analysis on the Physical Properties of the Kagome Superconductor CsV3Sb5
by Tianyi Han, Jiantao Che, Chenxiao Ye and Hai Huang
Crystals 2023, 13(2), 321; https://doi.org/10.3390/cryst13020321 - 15 Feb 2023
Cited by 3 | Viewed by 1936
Abstract
The kagome lattice consisting of corner-sharing triangles has been studied in the context of quantum physics for more than seventy years. For the novel discovered kagome superconductor CsV3Sb5, identifying the pairing symmetry of order parameter remained an elusive problem [...] Read more.
The kagome lattice consisting of corner-sharing triangles has been studied in the context of quantum physics for more than seventy years. For the novel discovered kagome superconductor CsV3Sb5, identifying the pairing symmetry of order parameter remained an elusive problem until now. Based on the two-band Ginzburg–Landau theory, we study the temperature dependence of upper critical field and magnetic penetration depth for this compound. All theoretical results are consistent with the experimental data, which strongly indicates the existence of two-gap s-wave superconductivity in this system. In addition, it is worth noting that the anisotropy of effective masses in the band with large (or small) gap is about 70 (or 2.4). With the calculation of the Kadowaki–Woods ratio as 0.58×105μΩ cm mol2 K2 mJ2, the semi-heavy-fermion feature is suggested in the compound CsV3Sb5. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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12 pages, 5253 KiB  
Article
Direct Evidence for Phase Transition Process of VC Precipitation from (Fe,V)3C in Low-Temperature V-Bearing Molten Iron
by Lei Cao, Desheng Chen, Xiaomeng Sang, Hongxin Zhao, Yulan Zhen, Lina Wang, Yahui Liu, Fancheng Meng and Tao Qi
Crystals 2023, 13(2), 175; https://doi.org/10.3390/cryst13020175 - 19 Jan 2023
Viewed by 1657
Abstract
V-bearing molten iron was obtained by adding Na2CO3 in the smelting process of vanadium titanomagnetite at low temperature. Two forms of V-rich carbides ((Fe,V)3C, VC) were detected in the V-bearing pig iron products. Once the smelting temperature was [...] Read more.
V-bearing molten iron was obtained by adding Na2CO3 in the smelting process of vanadium titanomagnetite at low temperature. Two forms of V-rich carbides ((Fe,V)3C, VC) were detected in the V-bearing pig iron products. Once the smelting temperature was above 1300 °C, most of the V in the raw ore was reduced into molten iron. Owning to the high content of V, the unsteady (Fe,V)3C solid solution decomposed along with the precipitation of graphite and VC during the solidification process. The presence of VC cluster and VC precursor in (Fe,V)3C was detected by transmission electron microscopy, which confirmed the possibility of this transition process at the atomic perspective. The transformation dramatically affected the compositions and properties of V-bearing pig iron and had important guiding significance for the actual production process. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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13 pages, 3015 KiB  
Article
GPU-Based Cellular Automata Model for Multi-Orient Dendrite Growth and the Application on Binary Alloy
by Jingjing Wang, Hongji Meng, Jian Yang and Zhi Xie
Crystals 2023, 13(1), 105; https://doi.org/10.3390/cryst13010105 - 6 Jan 2023
Cited by 1 | Viewed by 1835
Abstract
To simulate dendrite growth with different orientations more efficiently, a high-performance cellular automata (CA) model based on heterogenous central processing unit (CPU)+ graphics processing unit (GPU) architecture has been proposed in this paper. Firstly, the decentered square algorithm (DCSA) is used to simulate [...] Read more.
To simulate dendrite growth with different orientations more efficiently, a high-performance cellular automata (CA) model based on heterogenous central processing unit (CPU)+ graphics processing unit (GPU) architecture has been proposed in this paper. Firstly, the decentered square algorithm (DCSA) is used to simulate the morphology of dendrite with different orientations. Secondly, parallel algorithms are proposed to take full advantage of many cores by maximizing computational parallelism. Thirdly, in order to further improve the calculation efficiency, the task scheduling scheme using multi-stream is designed to solve the waiting problem among independent tasks, improving task parallelism. Then, the present model was validated by comparing its steady dendrite tip velocity with the Lipton–Glicksman–Kurz (LGK) analytical model, which shows great agreement. Finally, it is applied to simulate the dendrite growth of the binary alloy, which proves that the present model can not only simulate the clear dendrite morphology with different orientations and secondary arms, but also show a good agreement with the in situ experiment. In addition, compared with the traditional CPU model, the speedup of this model is up to 158×, which provides a great acceleration. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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7 pages, 1668 KiB  
Article
First-Principles Calculations of Structural and Mechanical Properties of Cu–Ni Alloys
by Yun Wei, Ben Niu, Qijun Liu, Zhengtang Liu and Chenglu Jiang
Crystals 2023, 13(1), 43; https://doi.org/10.3390/cryst13010043 - 26 Dec 2022
Cited by 8 | Viewed by 2521
Abstract
Nanostructured Cu–Ni alloys have become the focus of public attention due to their better corrosion resistance and high hardness in experimental measurements. First-principles calculation based on the density functional theory (DFT) has been confirmed as an effective tool and used to illustrate the [...] Read more.
Nanostructured Cu–Ni alloys have become the focus of public attention due to their better corrosion resistance and high hardness in experimental measurements. First-principles calculation based on the density functional theory (DFT) has been confirmed as an effective tool and used to illustrate the mechanical properties of these alloys. In this paper, the DFT has been employed to calculate the mechanical properties of Cu–Ni alloys, including bulk modulus, shear modulus, Young’s modulus, anisotropic index, Poisson’s ratio, average velocity, and B/G. We find that the Ni-rich Cu–Ni alloys have relatively higher mechanical parameters, and the Cu-rich alloys have smaller mechanical parameters, which is consistent with previous experiments. This provides an idea for us to design alloys to improve alloy strength. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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9 pages, 324 KiB  
Article
Boundary Effect and Critical Temperature of Two-Band Superconducting FeSe Films
by Chenxiao Ye, Jiantao Che and Hai Huang
Crystals 2023, 13(1), 18; https://doi.org/10.3390/cryst13010018 - 22 Dec 2022
Viewed by 1660
Abstract
Based on two-band Bogoliubov–de Gennes theory, we study the boundary effect of an interface between a two-gap superconductor FeSe and insulator (or vacuum). New boundary terms are introduced into two-band Ginzburg–Landau formalism, which modifies the boundary conditions for the corresponding order parameters of [...] Read more.
Based on two-band Bogoliubov–de Gennes theory, we study the boundary effect of an interface between a two-gap superconductor FeSe and insulator (or vacuum). New boundary terms are introduced into two-band Ginzburg–Landau formalism, which modifies the boundary conditions for the corresponding order parameters of superconductor. The theory allows for a mean-field calculation of the critical temperature suppression with the decrease in FeSe film thickness. Our numerical results are in good agreement with the experimental data observed in this material. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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12 pages, 7469 KiB  
Article
Hyperbolic Behavior and Antiferromagnetic Order in Rare-Earth Tellurides
by Jonathan Gjerde and Radi A. Jishi
Crystals 2022, 12(12), 1839; https://doi.org/10.3390/cryst12121839 - 16 Dec 2022
Cited by 4 | Viewed by 2244
Abstract
Quasi-2D materials have received much attention in recent years for their unusual physical properties. Among the most investigated of these materials are the rare-earth tellurides, which are primarily studied because they exhibit charge density waves and other quantum phenomena and have a high [...] Read more.
Quasi-2D materials have received much attention in recent years for their unusual physical properties. Among the most investigated of these materials are the rare-earth tellurides, which are primarily studied because they exhibit charge density waves and other quantum phenomena and have a high degree of tunability. In this paper, we examine the optical and magnetic properties of several rare-earth tellurides and find that they are antiferromagnetic materials with hyperbolic dispersion. Hyperbolic materials have very promising applications in sub-diffraction-limit optics, nanolithography, and spontaneous emission engineering, but these applications are hampered by low-quality hyperbolic materials. Rare-earth tellurides may provide insight into solving these issues if their properties can be properly tuned using the large variety of techniques already explored in the literature. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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10 pages, 8368 KiB  
Article
Dewetting Process in Ni-Mn-Ga Shape-Memory Heusler: Effects on Morphology, Stoichiometry and Magnetic Properties
by Milad Takhsha Ghahfarokhi, Federica Celegato, Gabriele Barrera, Francesca Casoli, Paola Tiberto and Franca Albertini
Crystals 2022, 12(12), 1826; https://doi.org/10.3390/cryst12121826 - 15 Dec 2022
Cited by 1 | Viewed by 1585
Abstract
In this work, dewetting process has been investigated in shape-memory Heuslers. To this aim, series of high-temperature annealing (1100–1150 K) have been performed at high vacuum (time is varied in the range of 55–165 min) in Ni-Mn-Ga epitaxial thin films grown on MgO(001). [...] Read more.
In this work, dewetting process has been investigated in shape-memory Heuslers. To this aim, series of high-temperature annealing (1100–1150 K) have been performed at high vacuum (time is varied in the range of 55–165 min) in Ni-Mn-Ga epitaxial thin films grown on MgO(001). The process kinetics have been followed by studying the evolution of morphology and composition. In particular, we report the initiation of the dewetting process by the formation of symmetric holes in the films. The holes propagate and integrate, leaving micrometric and submicron islands of the material, increasing the average roughness of the films by a factor of up to around 30. The dewetting process is accompanied by severe Ga and Mn sublimation, and Ni-Ga segregation, which significantly modify the magnetic properties of the films measured at each stage. The annealed samples show a relatively weak magnetic signal at room temperature with respect to the pristine sample. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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20 pages, 11517 KiB  
Article
The Presence of Charge Transfer Defect Complexes in Intermediate Band CuAl1−pFepS2
by Christopher Dickens, Adam O. J. Kinsella, Matt Watkins and Matthew Booth
Crystals 2022, 12(12), 1823; https://doi.org/10.3390/cryst12121823 - 14 Dec 2022
Viewed by 1702
Abstract
Despite chalcopyrite (CuFeS2) being one of the oldest known copper ores, it exhibits various properties that are still the subject of debate. For example, the relative concentrations of the ionic states of Fe and Cu in CuFeS2 can vary significantly [...] Read more.
Despite chalcopyrite (CuFeS2) being one of the oldest known copper ores, it exhibits various properties that are still the subject of debate. For example, the relative concentrations of the ionic states of Fe and Cu in CuFeS2 can vary significantly between different studies. The presence of a plasmon-like resonance in the visible absorption spectrum of CuFeS2 nanocrystals has driven a renewed interest in this material over recent years. The successful synthesis of CuAl1pFepS2 nanocrystals that exhibit a similar optical resonance has recently been demonstrated in the literature. In this study, we use density functional theory to investigate Fe substitution in CuAlS2 and find that the formation energy of neutral [FeCu]2++[CuAl]2 defect complexes is comparable to [FeAl]0 antisites when p0.5. Analysis of electron density and density of states reveals that charge transfer within these defect complexes leads to the formation of local Cu2+/Fe2+ ionic states that have previously been associated with the optical resonance in the visible absorption of CuFeS2. Finally, we comment on the nature of the optical resonance in CuAl1pFepS2 in light of our results and discuss the potential for tuning the optical properties of similar systems. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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10 pages, 2173 KiB  
Article
Investigation of Magnetocaloric Properties in the TbCo2-H System
by Galina Politova, Irina Tereshina, Ioulia Ovchenkova, Abdu-Rahman Aleroev, Yurii Koshkid’ko, Jacek Ćwik and Henryk Drulis
Crystals 2022, 12(12), 1783; https://doi.org/10.3390/cryst12121783 - 8 Dec 2022
Cited by 3 | Viewed by 1528
Abstract
In this work the magnetocaloric effect in the TbCo2-H system in the region of the Curie temperature was studied both by direct and indirect methods in external magnetic fields up to ~1.4 and 14 T, respectively. We have paid special attention [...] Read more.
In this work the magnetocaloric effect in the TbCo2-H system in the region of the Curie temperature was studied both by direct and indirect methods in external magnetic fields up to ~1.4 and 14 T, respectively. We have paid special attention to the magnetic and magnetothermal properties of the TbCo2–H with high hydrogen content. The mechanisms responsible for the change in the Curie temperature were established, and the field and temperature dependences of the magnetocaloric effect were analyzed in detail. In addition, the magnetocaloric properties (including critical parameters) for various systems based on the TbCo2 compound were compared. The main regularities of the change in the MCE value and the Curie temperature depending on the composition are discovered and discussed. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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28 pages, 18274 KiB  
Article
Hydrogen-Induced Order–Disorder Effects in FePd3
by André Götze, Siobhan Christina Stevenson, Thomas Christian Hansen and Holger Kohlmann
Crystals 2022, 12(12), 1704; https://doi.org/10.3390/cryst12121704 - 24 Nov 2022
Cited by 4 | Viewed by 1684
Abstract
Binary intermetallic compounds, such as FePd3, attract interests due to their physical, magnetic and catalytic properties. For a better understanding of their hydrogenation properties, both ordered FePd3 and disordered Fe0.25Pd0.75 are studied by several in situ methods, [...] Read more.
Binary intermetallic compounds, such as FePd3, attract interests due to their physical, magnetic and catalytic properties. For a better understanding of their hydrogenation properties, both ordered FePd3 and disordered Fe0.25Pd0.75 are studied by several in situ methods, such as thermal analysis, X-ray powder diffraction and neutron powder diffraction, at moderate hydrogen pressures up to 8.0 MPa. FePd3 absorbs small amounts of hydrogen at room temperature and follows Sieverts’ law of hydrogen solubility in metals. [Pd6] octahedral voids are filled up to 4.7(9)% in a statistical manner at 8.00(2) MPa, yielding the hydride FePd3H0.047(9). This is accompanied by decreasing long-range order of Fe and Pd atoms (site occupancy factor of Fe at Wyckoff position 1a decreasing from 0.875(3) to 0.794(4)). This trend is also observed during heating, while the ordered magnetic moment decreases up to the Curie temperature of 495(8) K. The temperature dependences of the magnetic moments of iron atoms in FePd3 under isobaric conditions (p(D2) = 8.2(2) MPa) are consistent with a 3D Ising or Heisenberg model (critical parameter β = 0.28(5)). The atomic and magnetic order and hydrogen content of FePd3 show a complex interplay. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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8 pages, 1190 KiB  
Article
Field-Induced Transition in (Nd,Dy)2Fe14B in Ultrahigh Magnetic Fields
by N. V. Kostyuchenko, I. S. Tereshina, A. I. Bykov, S. V. Galanova, R. V. Kozabaranov, A. S. Korshunov, I. S. Strelkov, I. V. Makarov, A. V. Filippov, Yu. B. Kudasov, D. A. Maslov, V. V. Platonov, O. M. Surdin, P. B. Repin, V. D. Selemir and A. K. Zvezdin
Crystals 2022, 12(11), 1615; https://doi.org/10.3390/cryst12111615 - 11 Nov 2022
Viewed by 1388
Abstract
We demonstrate the peculiarities of the magnetization process in the ferrimagnetic intermetallic compound (Nd0.5Dy0.5)2Fe14B, which has been studied theoretically and experimentally using ultrahigh magnetic fields. We observe phase transition induced by external ultrahigh magnetic fields [...] Read more.
We demonstrate the peculiarities of the magnetization process in the ferrimagnetic intermetallic compound (Nd0.5Dy0.5)2Fe14B, which has been studied theoretically and experimentally using ultrahigh magnetic fields. We observe phase transition induced by external ultrahigh magnetic fields (up to 170 T) and also describe the magnetization process analytically in terms of critical transition fields. In this work, the first and second critical fields of the field-induced magnetic transitions, Hc1 and Hc2, were estimated, and the results were verified against experimental data for Hc1. Critical field Hc2 predicting the place of transition to the forced-ferromagnetic state was estimated for the first time for (Nd0.5Dy0.5)2Fe14B compound. A comparison of the magnetization behavior for (Nd0.5Dy0.5)2Fe14B with the basic systems Nd2Fe14B and Dy2Fe14B is also performed. We demonstrate that, in the Dy2Fe14B compound, the field-induced transition type is changed from the first to the second order due to the replacement of the Nd atom by Dy one. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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21 pages, 5864 KiB  
Article
The Structural, Electronic, Magnetic and Elastic Properties of Full-Heusler Co2CrAl and Cr2MnSb: An Ab Initio Study
by Sara J. Yahya, Mohammed S. Abu-Jafar, Said Al Azar, Ahmad A. Mousa, Rabah Khenata, Doha Abu-Baker and Mahmoud Farout
Crystals 2022, 12(11), 1580; https://doi.org/10.3390/cryst12111580 - 6 Nov 2022
Cited by 3 | Viewed by 2748
Abstract
In this paper, the full-potential, linearized augmented plane wave (FP-LAPW) method was employed in investigating full-Heusler Co2CrA1’s structural, elastic, magnetic and electronic properties. The FP-LAPW method was employed in computing the structural parameters (bulk modulus, lattice parameters, c/a and first pressure [...] Read more.
In this paper, the full-potential, linearized augmented plane wave (FP-LAPW) method was employed in investigating full-Heusler Co2CrA1’s structural, elastic, magnetic and electronic properties. The FP-LAPW method was employed in computing the structural parameters (bulk modulus, lattice parameters, c/a and first pressure derivatives). The optimized structural parameters were determined by generalized gradient approximation (GGA) for the exchange-correlation potential, Vxc. Estimating the energy gaps for these compounds was accomplished through modified Becke–Johnson potential (mBJ). It was found that the conventional Heusler compound Co2CrA1 with mBJ and CGA approaches had a half-metallic character, and its spin-down configuration had an energy gap. It was also found that the conventional and inverse Heusler Cr2MnSb and tetragonal (139) (Co2CrA1, Cr2MnSb) compounds with a half-metallic character had direct energy gaps in the spin-down configuration. To a certain degree, the total magnetic moments for the two compounds were compatible with the theoretical and experimental results already attained. Mechanically, we found that the conventional and inverse full-Heusler compound Co2CrAl was stable, but the inverse Cr2MnSb was unstable in the ferromagnetic state. The conventional Heusler compound Cr2MnSb was mechanically stable in the ferromagnetic state. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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8 pages, 1910 KiB  
Article
Morphology and Growth Mechanism of β-Rhombohedral Boron and Pentagonal Twins in Cu Alloy
by Junqing Han, Wentao Yuan, Yihan Wen, Zuoshan Wei, Tong Gao, Yuying Wu and Xiangfa Liu
Crystals 2022, 12(11), 1516; https://doi.org/10.3390/cryst12111516 - 25 Oct 2022
Viewed by 2116
Abstract
In this work, boron particles with β-rhombohedral structure were prepared in Cu-4B alloy. The morphology and growth mechanism of β-B and pentagonal twins were analyzed. Results show that boron crystals possessed an approximate octahedral structure which consisted of two planes belonging to {001} [...] Read more.
In this work, boron particles with β-rhombohedral structure were prepared in Cu-4B alloy. The morphology and growth mechanism of β-B and pentagonal twins were analyzed. Results show that boron crystals possessed an approximate octahedral structure which consisted of two planes belonging to {001} facet and a rhombohedron formed by {101} planes. The morphology of the boron crystal was determined by the position and size of {001} planes. During growth, parts of boron crystal formed twins to reduce surface energy. Five particular single crystals can shape a pentagonal twin. The morphological distinction between pentagonal twins mainly came from the difference in morphology of single crystal. When the {001} exposed planes were large and showed a hexagonal shape, the boron crystal often formed parallel groupings and polysynthetic twins to reduce surface energy. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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Review

Jump to: Research

21 pages, 5931 KiB  
Review
An Overview on Synthesis, Processing and Applications of Nickel Aluminides: From Fundamentals to Current Prospects
by Santosh Sampath, Vignesh Pandian Ravi and Srivatsan Sundararajan
Crystals 2023, 13(3), 435; https://doi.org/10.3390/cryst13030435 - 2 Mar 2023
Cited by 11 | Viewed by 3707
Abstract
Nickel aluminides have desirable properties for use in high-temperature applications. Nickel aluminides have certain desirable qualities, but for almost a decade in the 1990s, those benefits were overshadowed by the challenges of processing and machining at room temperature. Manufacturing improvements, increased knowledge of [...] Read more.
Nickel aluminides have desirable properties for use in high-temperature applications. Nickel aluminides have certain desirable qualities, but for almost a decade in the 1990s, those benefits were overshadowed by the challenges of processing and machining at room temperature. Manufacturing improvements, increased knowledge of aluminide microstructure and deformation processes, and developments in micro-alloying have all contributed to the development of nickel aluminides. Key developments in nickel aluminides, such as their microstructure, alloy addition and alloy development, are given and discussed at length. Methods of production from the past, such as ingot metallurgy and investment casting and melting are addressed, and developments in powder metallurgy-based production methods are introduced. Finally, the difficulties of producing nickel aluminides and possible solutions are examined. This paper gives an overview of the fundamentals, preparation, processing, applications and current trends in nickel aluminides. Full article
(This article belongs to the Special Issue Intermetallic Compound (Volume II))
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