Special Issue "Intermetallics"

A special issue of Crystals (ISSN 2073-4352).

Deadline for manuscript submissions: closed (30 November 2015)

Special Issue Editor

Guest Editor
Dr. Duc Nguyen-Manh

1 Theory and Modelling Department, Culham Centre for Fusion Energy, UK
2 Atomic Energy Authority, Abingdon, Oxfordshire, OX14 3DB, UK
Website | E-Mail
Interests: advanced materials for nuclear applications; phase stability and transformations in alloys; first-principles prediction of intermetallics; multi-scale modelling of materials; magnetic behaviour of iron-based steels; thermal-mechanical properties of materials under irradiation; electronic structure and chemical bonding of nano-materials; high-entropy alloys

Special Issue Information

Dear Colleagues,

This Special Issue aims to promote international exchange and to share the latest knowledge and developments in all fundamental aspects of intermetallic-based materials encompassing characterization, testing, modelling and technological application. Emphasis is placed on innovative approaches and advanced overviews to understand complex relationship between the structure and functionality of new materials with improved properties. Of specific interest are the modelling methodologies in all scales based on first-principles, linking theoretical understanding with experimental observations. The topics include, but are not limited to, the thermodynamic, defect, magnetic, and mechanical properties of complex intermetallics including high-entropy alloys used for structural applications, etc.

Dr. Duc Nguyen-Manh
Guest Editor

Manuscript Submission Information

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Keywords

  • Advanced and functional intermetallic
  • Defect and diffusion in intermetallic
  • Microstructural deformation in intermetallic
  • Structure and stability of high-temperature intermetallic
  • High-throughput modelling and prediction of intermetallic
  • Magnetic, mechanical properties of intermetallic
  • Single-phase in multi-component high-entropy alloys

Published Papers (6 papers)

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Research

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Open AccessArticle PRINCEPS: A Computer-Based Approach to the Structural Description and Recognition of Trends within Structural Databases, and Its Application to the Ce-Ni-Si System
Crystals 2016, 6(4), 35; doi:10.3390/cryst6040035
Received: 6 December 2015 / Revised: 17 March 2016 / Accepted: 22 March 2016 / Published: 1 April 2016
Cited by 1 | PDF Full-text (10151 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Intermetallic crystal structures offer an enormous structural diversity, with an endless array of structural motifs whose connection to stability and physical properties are often mysterious. Making sense of the often complex crystal structures that arise here, developing a clear structural description, and identifying
[...] Read more.
Intermetallic crystal structures offer an enormous structural diversity, with an endless array of structural motifs whose connection to stability and physical properties are often mysterious. Making sense of the often complex crystal structures that arise here, developing a clear structural description, and identifying connections to other phases can be laborious and require an encyclopedic knowledge of structure types. In this Article, we present PRINCEPS, an algorithm based on a new coordination environment projection scheme that facilitates the structural analysis and comparison of such crystal structures. We demonstrate the potential of this approach by applying it to the complex Ce-Ni-Si ternary system, whose 17 binary and 21 ternary phases would present a daunting challenge to one seeking to understand the system by manual inspection (but has nonetheless been well-described through the heroic efforts of previous researchers). With the help of PRINCEPS, most of the ternary phases in this system can be rationalized as intergrowths of simple structural fragments, and grouped into a handful of structural series (with some outliers). These results illustrate how the PRINCEPS approach can be used to organize a vast collection of crystal structures into structurally meaningful families, and guide the description of complex atomic arrangements. Full article
(This article belongs to the Special Issue Intermetallics)
Open AccessArticle Crystal-Structure Analysis with Moments of the Density-of-States: Application to Intermetallic Topologically Close-Packed Phases
Crystals 2016, 6(2), 18; doi:10.3390/cryst6020018
Received: 5 November 2015 / Revised: 22 January 2016 / Accepted: 25 January 2016 / Published: 2 February 2016
Cited by 3 | PDF Full-text (1608 KB) | HTML Full-text | XML Full-text
Abstract
The moments of the electronic density-of-states provide a robust and transparent means for the characterization of crystal structures. Using d-valent canonical tight-binding, we compute the moments of the crystal structures of topologically close-packed (TCP) phases as obtained from density-functional theory (DFT) calculations. We
[...] Read more.
The moments of the electronic density-of-states provide a robust and transparent means for the characterization of crystal structures. Using d-valent canonical tight-binding, we compute the moments of the crystal structures of topologically close-packed (TCP) phases as obtained from density-functional theory (DFT) calculations. We apply the moments to establish a measure for the difference between two crystal structures and to characterize volume changes and internal relaxations. The second moment provides access to volume variations of the unit cell and of the atomic coordination polyhedra. Higher moments reveal changes in the longer-ranged coordination shells due to internal relaxations. Normalization of the higher moments leads to constant (A15,C15) or very similar (χ, C14, C36, μ, and σ) higher moments of the DFT-relaxed TCP phases across the 4d and 5d transition-metal series. The identification and analysis of internal relaxations is demonstrated for atomic-size differences in the V-Ta system and for different magnetic orderings in the C14-Fe 2 Nb Laves phase. Full article
(This article belongs to the Special Issue Intermetallics)
Open AccessArticle Formation Mechanism of Porous Cu3Sn Intermetallic Compounds by High Current Stressing at High Temperatures in Low-Bump-Height Solder Joints
Crystals 2016, 6(1), 12; doi:10.3390/cryst6010012
Received: 22 November 2015 / Revised: 4 January 2016 / Accepted: 11 January 2016 / Published: 16 January 2016
Cited by 7 | PDF Full-text (3311 KB) | HTML Full-text | XML Full-text
Abstract
Electromigration tests of SnAg solder bump samples with 15 μm bump height and Cu under-bump-metallization (UBM) were performed. The test conditions were 1.45 × 104 A/cm2 at 185 °C and 1.20 × 104 A/cm2 at 0 °C. A porous
[...] Read more.
Electromigration tests of SnAg solder bump samples with 15 μm bump height and Cu under-bump-metallization (UBM) were performed. The test conditions were 1.45 × 104 A/cm2 at 185 °C and 1.20 × 104 A/cm2 at 0 °C. A porous Cu3Sn intermetallic compound (IMC) structure was observed to form within the bumps after several hundred hours of current stressing. In direct comparison, annealing alone at 185 °C will take more than 1000 h for porous Cu3Sn to form, and it will not form at 170 °C even after 2000 h. Here we propose a mechanism to explain the formation of this porous structure assisted by electromigration. The results show that the SnAg bump with low bump height will become porous-type Cu3Sn when stressing with high current density and high temperature. Polarity effects on porous Cu3Sn formation is discussed. Full article
(This article belongs to the Special Issue Intermetallics)
Open AccessArticle Enthalpies of Formation of Transition Metal Diborides: A First Principles Study
Crystals 2015, 5(4), 562-582; doi:10.3390/cryst5040562
Received: 31 August 2015 / Accepted: 9 November 2015 / Published: 19 November 2015
PDF Full-text (3446 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The enthalpies of formation of transition metals diborides in various structures have been obtained from density functional theory (DFT) calculations in order to determine the ground state at T = 0 K and p = 0. The evolution of the enthalpies of formation
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The enthalpies of formation of transition metals diborides in various structures have been obtained from density functional theory (DFT) calculations in order to determine the ground state at T = 0 K and p = 0. The evolution of the enthalpies of formation along the 3D, 4D, and 5D series has been correlated to the considered crystal structures. In the whole, the calculated values of the enthalpies of formation of the diborides in their ground state are in good agreement with the experimental ones when available. The calculated values of the lattice parameters at T = 0 K of the ground state agree well with the experimental values. The total and partial electronic densities of states have been computed. Special features of the transition metal electronic partial density of states have been evidenced and correlated to the local environment of the atoms. Full article
(This article belongs to the Special Issue Intermetallics)

Review

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Open AccessReview A Review on the Properties of Iron Aluminide Intermetallics
Crystals 2016, 6(1), 10; doi:10.3390/cryst6010010
Received: 31 August 2015 / Revised: 19 December 2015 / Accepted: 4 January 2016 / Published: 14 January 2016
Cited by 10 | PDF Full-text (6813 KB) | HTML Full-text | XML Full-text
Abstract
Iron aluminides have been among the most studied intermetallics since the 1930s, when their excellent oxidation resistance was first noticed. Their low cost of production, low density, high strength-to-weight ratios, good wear resistance, ease of fabrication and resistance to high temperature oxidation and
[...] Read more.
Iron aluminides have been among the most studied intermetallics since the 1930s, when their excellent oxidation resistance was first noticed. Their low cost of production, low density, high strength-to-weight ratios, good wear resistance, ease of fabrication and resistance to high temperature oxidation and sulfurization make them very attractive as a substitute for routine stainless steel in industrial applications. Furthermore, iron aluminides allow for the conservation of less accessible and expensive elements such as nickel and molybdenum. These advantages have led to the consideration of many applications, such as brake disks for windmills and trucks, filtration systems in refineries and fossil power plants, transfer rolls for hot-rolled steel strips, and ethylene crackers and air deflectors for burning high-sulfur coal. A wide application for iron aluminides in industry strictly depends on the fundamental understanding of the influence of (i) alloy composition; (ii) microstructure; and (iii) number (type) of defects on the thermo-mechanical properties. Additionally, environmental degradation of the alloys, consisting of hydrogen embrittlement, anodic or cathodic dissolution, localized corrosion and oxidation resistance, in different environments should be well known. Recently, some progress in the development of new micro- and nano-mechanical testing methods in addition to the fabrication techniques of micro- and nano-scaled samples has enabled scientists to resolve more clearly the effects of alloying elements, environmental items and crystal structure on the deformation behavior of alloys. In this paper, we will review the extensive work which has been done during the last decades to address each of the points mentioned above. Full article
(This article belongs to the Special Issue Intermetallics)
Open AccessReview Dendrite Growth Kinetics in Undercooled Melts of Intermetallic Compounds
Crystals 2015, 5(3), 355-375; doi:10.3390/cryst5030355
Received: 2 June 2015 / Revised: 6 August 2015 / Accepted: 27 August 2015 / Published: 7 September 2015
Cited by 9 | PDF Full-text (3485 KB) | HTML Full-text | XML Full-text
Abstract
Solidification needs an undercooling to drive the solidification front. If large undercoolings are achieved, metastable solid materials are solidified from the undercooled melt. Containerless processing provides the conditions to achieve large undercoolings since heterogeneous nucleation on container walls is completely avoided. In the
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Solidification needs an undercooling to drive the solidification front. If large undercoolings are achieved, metastable solid materials are solidified from the undercooled melt. Containerless processing provides the conditions to achieve large undercoolings since heterogeneous nucleation on container walls is completely avoided. In the present contribution both electromagnetic and electrostatic levitation are applied. The velocity of rapidly advancing dendrites is measured as a function of undercooling by a High-Speed-Camera. The dendrite growth dynamics is investigated in undercooled melts of intermetallic compounds. The Al50Ni50 alloy is studied with respect to disorder trapping that leads to a disordered superlattice structure if the melt is undercooled beyond a critical undercooling. Disorder trapping is evidenced by in situ energy dispersive diffraction using synchrotron radiation of high intensity to record full diffraction pattern on levitated samples within a short time interval. Experiments on Ni2B using different processing techniques of varying the level of convection reveal convection-induced faceting of rapidly growing dendrites. Eventually, the growth velocity is measured in an undercooled melt of glass forming Cu50Zr50 alloy. A maximum in the growth velocity–undercooling relation is proved. This is understood by the fact that the temperature dependent diffusion coefficient counteracts the thermodynamic driving force for rapid growth if the temperature of the undercooled melt is approaching the temperature regime above the glass transition temperature. The analysis of this result allows for determining the activation energy of atomic attachment kinetics at the solid–liquid interface that is comparable to the activation energy of atomic diffusion as determined by independent measurements of the atomic diffusion in undercooled Cu50Zr50 alloy melt. Full article
(This article belongs to the Special Issue Intermetallics)

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