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Special Issue "Thermo-Mechanical Behaviour of Structural Lightweight Alloys"

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

Deadline for manuscript submissions: 31 October 2018

Special Issue Editor

Guest Editor
Prof. Dr. Guillermo Requena

Department of Metallic Structures and Hybrid Materials Systems, Institute for Materials Research, German Aerospace Centre, Linder Höhe, 51147, Cologne, Germany
Website | E-Mail
Interests: light alloys; metals for additive manufacturing; three-dimensional material characterization; synchrotron tomography; high energy synchrotron diffraction; aluminum alloys; titanium alloys; magnesium alloys; titanium aluminides; metal matrix composites; phase transformations; relationships microstructure-properties; thermo-mechanical behavior of metals

Special Issue Information

Dear Colleagues,

The need to reduce the ecological footprint of (water, land, air) vehicles in this era of climate change requires pushing the limits in the development of lightweight structures and materials.

The development and optimization of lightweight metals for structural components requires a thorough understanding of their thermo-mechanical behavior at several stages of the production chain, as well during service conditions. For instance, thermo-mechanical treatments play a decisive role in the processing of wrought products and are beginning to see the light for application in wire-based additive manufacturing technologies. During service, the response of lightweight alloys under the simultaneous influence of mechanical loads and temperature can determine the lifetime and performance of a multitude of structural components used for transportation such as in combustion engines or aircraft turbines.

The present Special Issue is dedicated to disseminate current efforts around the globe aiming at advancing in the understanding of the thermo-mechanical behavior of structural lightweight alloys under processing or service conditions. It is therefore my pleasure to invite you to submit contributions that may take into account this thematic from and experimental or theoretical point of view for Mg, Al, Ti, TiAl alloys, as well innovative composites based on these systems or new lightweight metals.

Prof. Guillermo Requena
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 papers will be 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. Materials 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 1600 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

  • Aluminum alloys
  • magnesium alloys
  • titanium alloys
  • titanium aluminides
  • lightweight metals
  • thermo-mechanical behavior

Published Papers (5 papers)

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Research

Open AccessFeature PaperArticle The Effect of Zn Content on the Mechanical Properties of Mg-4Nd-xZn Alloys (x = 0, 3, 5 and 8 wt.%)
Materials 2018, 11(7), 1103; https://doi.org/10.3390/ma11071103
Received: 30 April 2018 / Revised: 19 June 2018 / Accepted: 25 June 2018 / Published: 28 June 2018
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Abstract
The mechanical properties of as-cast Mg-4Nd-xZn (x = 0, 3, 5 or 8 wt.%) alloys were investigated both in situ and ex situ in as-cast and solution-treated conditions. The additions of 3 or 5 wt.% Zn in the base Mg-4Nd alloy did not
[...] Read more.
The mechanical properties of as-cast Mg-4Nd-xZn (x = 0, 3, 5 or 8 wt.%) alloys were investigated both in situ and ex situ in as-cast and solution-treated conditions. The additions of 3 or 5 wt.% Zn in the base Mg-4Nd alloy did not improve yield strength in comparison to the binary Mg-4Nd alloy. Mechanical properties were shown to improve only with the relatively high concentration of 8 wt.% Zn to Mg-4Nd. The change in intermetallic morphology from a continuous intermetallic to a lamella-like intermetallic was the primary reason for the decreased mechanical properties in Mg-4Nd-3Zn and Mg-4Nd-5Zn compared with Mg-4Nd and Mg-4Nd-8Zn. The dissolution of intermetallic at grain boundaries following heat treatment further indicated the importance of grain boundary reinforcement as shown in both in situ and ex situ compression testing. Azimuthal angle-time plots indicated little grain rotation most noticeably in Mg-4Nd, which also indicated the influence of a strong intermetallic network along the grain boundaries. Full article
(This article belongs to the Special Issue Thermo-Mechanical Behaviour of Structural Lightweight Alloys)
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Open AccessArticle Maintaining High Strength in Mg-LPSO Alloys with Low Yttrium Content Using Severe Plastic Deformation
Materials 2018, 11(5), 733; https://doi.org/10.3390/ma11050733
Received: 5 April 2018 / Revised: 27 April 2018 / Accepted: 2 May 2018 / Published: 5 May 2018
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Abstract
Alternative processing routes such as powder metallurgy, the extrusion of recycled chips, or equal channel angular pressing (ECAP) have been considered for effective methods of maintaining the high mechanical strength of Mg-Y-Zn alloys containing long-period stacking ordered structures with respect to the alloy
[...] Read more.
Alternative processing routes such as powder metallurgy, the extrusion of recycled chips, or equal channel angular pressing (ECAP) have been considered for effective methods of maintaining the high mechanical strength of Mg-Y-Zn alloys containing long-period stacking ordered structures with respect to the alloy processed by the conventional extrusion of as-cast ingots with the advantage of minimizing the yttrium content. A yield stress similar to that found for extruded Mg97Y2Zn1 alloy can be attained with only half of the usual yttrium and zinc additions thanks to the grain refinement induced by ECAP processing. The properties of Mg98.5Y1Zn0.5 subjected to ECAP are maintained up to 200 °C, but superplastic behavior is found above this temperature when the alloy is processed through a powder metallurgy route. Full article
(This article belongs to the Special Issue Thermo-Mechanical Behaviour of Structural Lightweight Alloys)
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Open AccessArticle Microstructure, Mechanical Properties, and Corrosion Resistance of Thermomechanically Processed AlZn6Mg0.8Zr Alloy
Materials 2018, 11(4), 570; https://doi.org/10.3390/ma11040570
Received: 7 March 2018 / Revised: 3 April 2018 / Accepted: 4 April 2018 / Published: 7 April 2018
Cited by 1 | PDF Full-text (27396 KB) | HTML Full-text | XML Full-text
Abstract
The paper presents results of the investigations on the effect of low-temperature thermomechanical treatment (LTTT) on the microstructure of AlZn6Mg0.8Zr alloy (7000 series) and its mechanical properties as well as electrochemical and stress corrosion resistance. For comparison of the LTTT effect, the alloy
[...] Read more.
The paper presents results of the investigations on the effect of low-temperature thermomechanical treatment (LTTT) on the microstructure of AlZn6Mg0.8Zr alloy (7000 series) and its mechanical properties as well as electrochemical and stress corrosion resistance. For comparison of the LTTT effect, the alloy was subjected to conventional precipitation hardening. Comparative studies were conducted in the fields of metallographic examinations and static tensile tests. It was found that mechanical properties after the LTTT were better in comparison to after conventional heat treatment (CHT). The tested alloy after low-temperature thermomechanical treatment with increasing plastic deformation shows decreased electrochemical corrosion resistance during potentiodynamic tests. The alloy after low-temperature thermomechanical treatment with deformation degree in the range of 10 to 30% is characterized by a high resistance to stress corrosion specified by the level of PSCC indices. Full article
(This article belongs to the Special Issue Thermo-Mechanical Behaviour of Structural Lightweight Alloys)
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Open AccessArticle Strengthening of Aluminum Wires Treated with A206/Alumina Nanocomposites
Materials 2018, 11(3), 413; https://doi.org/10.3390/ma11030413
Received: 9 February 2018 / Revised: 28 February 2018 / Accepted: 9 March 2018 / Published: 10 March 2018
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Abstract
This study sought to characterize aluminum nanocomposite wires that were fabricated through a cold-rolling process, having potential applications in TIG (tungsten inert gas) welding of aluminum. A206 (Al-4.5Cu-0.25Mg) master nanocomposites with 5 wt % γAl2O3 nanoparticles were first manufactured through
[...] Read more.
This study sought to characterize aluminum nanocomposite wires that were fabricated through a cold-rolling process, having potential applications in TIG (tungsten inert gas) welding of aluminum. A206 (Al-4.5Cu-0.25Mg) master nanocomposites with 5 wt % γAl2O3 nanoparticles were first manufactured through a hybrid process combining semi-solid mixing and ultrasonic processing. A206/1 wt % γAl2O3 nanocomposites were fabricated by diluting the prepared master nanocomposites with a monolithic A206 alloy, which was then added to a pure aluminum melt. The fabricated Al–γAl2O3 nanocomposite billet was cold-rolled to produce an Al nanocomposite wire with a 1 mm diameter and a transverse area reduction of 96%. Containing different levels of nanocomposites, the fabricated samples were mechanically and electrically characterized. The results demonstrate a significantly higher strength of the aluminum wires with the nanocomposite addition. Further, the addition of alumina nanoparticles affected the wires’ electrical conductivity compared with that of pure aluminum and aluminum–copper alloys. The overall properties of the new material demonstrate that these wires could be an appealing alternative for fillers intended for aluminum welding. Full article
(This article belongs to the Special Issue Thermo-Mechanical Behaviour of Structural Lightweight Alloys)
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Open AccessArticle Achieving High Strength and Good Ductility in As-Extruded Mg–Gd–Y–Zn Alloys by Ce Micro-Alloying
Materials 2018, 11(1), 102; https://doi.org/10.3390/ma11010102
Received: 10 December 2017 / Revised: 1 January 2018 / Accepted: 3 January 2018 / Published: 10 January 2018
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Abstract
In this study, the effect of Ce additions on microstructure evolution of Mg–7Gd–3.5Y–0.3Zn (wt %) alloys during the casting, homogenization, aging and extrusion processing are investigated, and novel mechanical properties are also obtained. The results show that Ce addition promotes the formation of
[...] Read more.
In this study, the effect of Ce additions on microstructure evolution of Mg–7Gd–3.5Y–0.3Zn (wt %) alloys during the casting, homogenization, aging and extrusion processing are investigated, and novel mechanical properties are also obtained. The results show that Ce addition promotes the formation of long period stacking ordered (LPSO) phases in the as-cast Mg–Gd–Y–Zn–Ce alloys. A high content of Ce addition would reduce the maximum solubility of Gd and Y in the Mg matrix, which leads to the higher density of Mg12Ce phases in the as-homogenized alloys. The major second phases observed in the as-extruded alloys are micron-sized bulk LPSO phases, nano-sized stripe LPSO phases, and broken Mg12Ce and Mg5RE phases. Recrystallized grain size of the as-extruded 0.2Ce, 0.5Ce and 1.0Ce alloys can be refined to ~4.3 μm, ~1.0 μm and ~8.4 μm, respectively, which is caused by the synthesized effect of both micron phases and nano phases. The strength and ductility of as-extruded samples firstly increase and then decrease with increasing Ce content. As-extruded 0.5Ce alloy exhibits optimal mechanical properties, with ultimate strength of 365 MPa and ductility of ~15% simultaneously. Full article
(This article belongs to the Special Issue Thermo-Mechanical Behaviour of Structural Lightweight Alloys)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Microstructure evolution in wrought aluminium alloys during thermomechanical loads
Authors: Cecilia Poletti et al.
Abstract: Thermal and thermomechanical loads during processing of age hardenable wrought aluminium alloys induce microstructural changes that involve the movement of dislocations, their arrangement and annihilation, the movement of boundaries, and the formation/dissolution of phases. Experiments are carried out and designed to isolate thermomechanical steps along typical production routes to understand and describe physical phenomena and their interactions. In this work we physically simulate the thermomechanical process by means of cold and hot compression and torsion tests using a Gleeble ® 3800 machine to produce flow data as well as deformed samples for metallography. We use electron back scattered diffraction and synchrotron in situ experiments to obtain crystallographic information during and after plastic deformation and heat treatments. Our developed models based on dislocation densities and misorientation evolutions can describe strain hardening, dynamic recovery, continuous dynamic recrystallization and static recrystallization. The microstructure after the initial stages of the plastic deformation is composed by cells. As the deformation proceeds, both the amount of dislocation at the cell walls and the misorienation among neighbouring cells/grains increase. We use two approaches to model the subgrain structure. In the first approach, valid for moderated strains, it is assumed that the misorientation reaches a saturation after hardening. The second approach results in a continuous increment of the misorientation until a maximum value is reached, allowing the formation new high angle grain boundaries by continuous dynamic recrystallization, thus refining the microstructure at large strains. Finally, the precipitates and other intermetallic particles retard the movement of dislocations and boundaries in general. Considering this, it was demonstrated that they have special impact in the static recrystallization during subsequent heat treatments.

Title: Development of Mechanical Properties During and After Welding
Authors: Michael Reich et al.

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