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Symmetry
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Materials Science and Symmetry
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Materials Science and Symmetry

A special issue of Symmetry (ISSN 2073-8994). This special issue belongs to the section "Chemistry: Symmetry/Asymmetry".

Deadline for manuscript submissions: closed (30 September 2023) | Viewed by 5402

Special Issue Editor

Dr. Teik-Cheng Lim

E-Mail Website
Guest Editor
School of Science and Technology, Singapore University of Social Sciences, Clementi Road, Singapore, Singapore
Interests: auxetics; auxetic materials; plates and shells
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

From the traditional “heat it and beat it” and the “structure-property-processing” science to architected microstructures and programmable metamaterials, the field of materials science has progressed beyond what the pioneers had earlier imagined. Alongside this development, our understanding of materials science has been intrinsically linked to the microstructural geometry of both naturally occurring and artificially created materials. This Special Issue is thus launched to celebrate the area of materials science in all its sub-fields, in their broadest sense possible, with a special focus on the role of micro-lattice symmetry in governing the effective physical properties of new materials.

Dr. Teik-Cheng Lim
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • materials science
  • materials engineering
  • metamaterials
  • nanomaterials
  • symmetry

Published Papers (4 papers)

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Research

13 pages, 13685 KiB  
Article
Electron Microscopy Study of Structural Defects Formed in Additively Manufactured AlSi10Mg Alloy Processed by Equal Channel Angular Pressing
by Przemysław Snopiński
Symmetry 2023, 15(4), 860; https://doi.org/10.3390/sym15040860 - 04 Apr 2023
Cited by 4 | Viewed by 1192
Abstract
This study focused on electron microscopy studies of microstructural defects formed in an additively manufactured (AM) AlSi10Mg alloy as a result of post-deformation by equal channel angular pressing (ECAP), with the aim of elucidating the fundamental deformation mechanisms that govern the plasticity of [...] Read more.
This study focused on electron microscopy studies of microstructural defects formed in an additively manufactured (AM) AlSi10Mg alloy as a result of post-deformation by equal channel angular pressing (ECAP), with the aim of elucidating the fundamental deformation mechanisms that govern the plasticity of both the aluminium matrix and the silicon phase. This article focused on the process of grain refinement, metastable phase transformations, and microstructural defects such as stacking faults or amorphous areas that severely disrupt the face-centred cubic (FCC) crystal lattice symmetry. The findings presented in this study imply that deformation twinning, phase transformation, and amorphization are not mutually exclusive modes of Si phase deformation. Both can occur at an ECAP temperature of 150 °C. At a deformation temperature of 100 °C, amorphization is the dominant deformation mode of the Si phase. It was also discovered that dislocation slip was the predominant deformation mode of Al matrix at 150 °C, while at 100 °C, additionally stacking faults were formed within the Al matrix. The present findings provide not only a fundamental understanding of the deformation micro-mechanism of the SLMed AlSi10Mg alloy but also open a new horizon for the development of the next generation of structural materials. Full article
(This article belongs to the Special Issue Materials Science and Symmetry)
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14 pages, 4028 KiB  
Article
Synthesis, Molecular, and Supramolecular Structures of Two Azide-Bridged Cd(II) and Cu(II) Coordination Polymers
by Mezna Saleh Altowyan, Eman M. Fathalla, Jörg H. Albering, Assem Barakat, Morsy A. M. Abu-Youssef, Saied M. Soliman and Ahmed M. A. Badr
Symmetry 2023, 15(3), 619; https://doi.org/10.3390/sym15030619 - 01 Mar 2023
Cited by 1 | Viewed by 1318
Abstract
Two 1D coordination polymers were synthesized by reaction of two ligands, 2-amino-4-picoline (2A4Pic) and quinoline-6-carboxylic acid (Qu-6-COOH) with two metal (II) nitrate (M = Cd and Cu) in the presence of azide as a linker. The synthesized metal complexes [...] Read more.
Two 1D coordination polymers were synthesized by reaction of two ligands, 2-amino-4-picoline (2A4Pic) and quinoline-6-carboxylic acid (Qu-6-COOH) with two metal (II) nitrate (M = Cd and Cu) in the presence of azide as a linker. The synthesized metal complexes [Cd(2A4Pic)2(N3)2]n; (1) and [Cu(Qu-6-COO)(N3)(H2O)]n; (2) were isolated in single crystals and their X-ray structures revealed a 1D polymeric structure. Due to symmetry considerations, the asymmetric formula is half a [Cd(2A4Pic)2(N3)2] unit for 1 and one [Cu(Qu-6-COO)(N3)(H2O)] unit for 2. In complex 1, the Cd(II) is hexa-coordinated with two 2A4Pic molecules and four μ(1,1) azide units. Hence, the CdN6 coordination environment has a slightly distorted octahedral geometry. In 2, the Cu(II) is hexa-coordinated with three different ligands (Qu-6-COO¯, H2O and μ(1,1) N3¯) where all are connectors between the crystallographically related Cu(II) sites. Additionally, complex 2 distorted CuN2O4 octahedral geometry. In both complexes, the polymer arrays are connected by N…H hydrogen bonds and π–π stacking interactions. Based on Hirshfeld analysis, the percentages of N…H contacts are 43.1 and 27.4% for 1 and 2, respectively, while %C...C are 5.6 and 9.3%, respectively. Analysis of Cu-N, Cu-O, and Cd-N bonds using DFT calculations showed predominantly closed-shell coordination interactions with little covalent characters. Additionally, the negatively charged ligand groups were found to compensate the positive charge of the central metal ion to a larger extent than the electrically neutral ligands. Full article
(This article belongs to the Special Issue Materials Science and Symmetry)
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19 pages, 2126 KiB  
Article
Metamaterial with Tunable Positive and Negative Hygrothermal Expansion Inspired by a Four-Fold Symmetrical Islamic Motif
by Teik-Cheng Lim
Symmetry 2023, 15(2), 462; https://doi.org/10.3390/sym15020462 - 09 Feb 2023
Cited by 3 | Viewed by 1395
Abstract
A metamaterial with controllable positive and negative thermal and hygroscopic expansions is investigated herein by inspiration from a range of Islamic geometric patterns. Constructing from eight pairs of pin-jointed Y-elements, each unit cell manifests eight rhombi that are arranged circumferentially, thereby manifesting four [...] Read more.
A metamaterial with controllable positive and negative thermal and hygroscopic expansions is investigated herein by inspiration from a range of Islamic geometric patterns. Constructing from eight pairs of pin-jointed Y-elements, each unit cell manifests eight rhombi that are arranged circumferentially, thereby manifesting four axes of symmetry. By attachment of bimaterial spiral springs of contrasting expansion coefficients to the far arms of the paired Y-elements, a change in the environment’s thermal or hygroscopic condition alters the offset angle of the paired Y-elements such that the unit cell of the metamaterial ranges from the eight-pointed star to the regular octagon. The effective coefficient of thermal expansion (CTE) and the coefficient of moisture expansion (CME) of this metamaterial were developed for small and large changes in environmental fluctuations using infinitesimal and finite models, respectively. Generated data indicates that the sign and magnitude of the effective thermal and hygroscopic expansion coefficients can be controlled by geometrical descriptors of the bimaterial spiral spring—such as its coil number and the ratio of its mean radius to its thickness—as well as the properties of the bimaterial’s layers such as their expansion coefficients, Young’s moduli and, in the case of effective hygroscopic expansion, their relative absorptivity. The obtained results suggest that the proposed metamaterial can be designed to perform as highly sensitive thermal and/or moisture sensors, as well as other functional materials or devices that take advantage of environmental changes as stimuli. Full article
(This article belongs to the Special Issue Materials Science and Symmetry)
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21 pages, 10174 KiB  
Article
Bonding of Dissimilar Metals in the Interlayer Region in Al-Based Composites: Molecular Dynamics
by Polina V. Polyakova, Julia A. Baimova and Radik R. Mulyukov
Symmetry 2023, 15(2), 328; https://doi.org/10.3390/sym15020328 - 24 Jan 2023
Cited by 2 | Viewed by 1062
Abstract
The aluminum–matrix composites possess are very important for future applications because they have unique mechanical properties. Here, molecular dynamics is used to analyze the bonding of dissimilar metals on the interface of Al/Mg, Al/Ti, and Al/Cu interfaces during deformation treatment–compression combined with shear [...] Read more.
The aluminum–matrix composites possess are very important for future applications because they have unique mechanical properties. Here, molecular dynamics is used to analyze the bonding of dissimilar metals on the interface of Al/Mg, Al/Ti, and Al/Cu interfaces during deformation treatment–compression combined with shear at room temperature. The terminal-mechanical treatment used in this simulation is a variant of the experimental technique applied to fabricate Al/Metal composites. It is found that there is a critical value of compressive and shear strain required to obtain the strong mixed Al/Metal interface. The diffusion depth of atoms of both components is dependent on the applied strain: (i) linear relationship for Al/Mg; (ii) logarithmic relationship for Al/Ti and Al/Cu. The mechanical behavior under tension and fracture analysis of the obtained interfaces are discussed in terms of atomic-level structural features which allow an understanding of the interconnection between the mechanical behavior and structure mixture near the interface. One of the important criteria for atomic mixing is the symmetry of the interface. After atomic mixing, Al/Ti composite has the highest ultimate tensile strength, Al/Cu—the average, and Al/Mg—the lowest between the considered interfaces, while the fracture strain of Al/Mg and Al/Ti composites are very close and higher than for Al/Cu. The obtained results are significant for the development of fabrication of Al/Metal interface by high-pressure torsion in practice. Full article
(This article belongs to the Special Issue Materials Science and Symmetry)
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