Special Issue "Spark Plasma Sintering of Metals and Metal Matrix Nanocomposites"

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Powder Metallurgy".

Deadline for manuscript submissions: 31 March 2021.

Special Issue Editor

Dr. Andrea García-Junceda
Website
Guest Editor
European Commission, DG Joint Research Centre, Nuclear Safety and Security Directorate, Westerduinweg 3, 1755 LE Petten, The Netherlands
Interests: advanced metallic materials design; powder metallurgy; microstructural and mechanical characterization.

Special Issue Information

Dear Colleagues,

Spark plasma sintering (SPS) is a rapid sintering technique combining the simultaneous use of a pulsed direct current with a uniaxial pressure to consolidate powder materials. This technique has attracted considerable attention in the last two decades due to the advantages that it offers over other more conventional sintering process. The main improvements of SPS are the shorter sintering times needed to obtain highly dense bulk materials with limited grain growth. Therefore, this technique is particularly suitable to process nanostructured materials with good densification and outstanding mechanical properties. In recent years, it has been widely applied to sinter many different advanced materials such as intermetallic compounds, hard metals, ceramics, metal matrix composites (MMC), and metallic alloys.

This Special Issue will address and gather the advances achieved in different metals and metal matrix nanocomposites processed by SPS, from both experimental and theoretical (modelling and simulation) perspectives. In particular, articles from the academic community or industry including advanced microstructural and mechanical characterization techniques (SEM, TEM, FIB, EBSD, TKD, EELS, AFM, APT, tomography, nanoindentation tests, in situ mechanical tests, small punch tests, etc.) assessing processing–structure–properties relationships are welcome. Articles related to the sintering of parts with a complex shape are also desirable.

Dr. Andrea García-Junceda
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. Metals 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 1800 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

  • Spark plasma sintering
  • FAST
  • Consolidation
  • Powder metallurgy
  • Metals
  • Metal matrix nanocomposites
  • Characterization
  • Modelling
  • Simulation.

Published Papers (6 papers)

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Research

Open AccessFeature PaperArticle
Magnetic Field Generated during Electric Current-Assisted Sintering: From Health and Safety Issues to Lorentz Force Effects
Metals 2020, 10(12), 1653; https://doi.org/10.3390/met10121653 - 08 Dec 2020
Abstract
In the past decade, a renewed interest on electromagnetic processing of materials has motivated several investigations on the interaction between matter, electric and magnetic fields. These effects are primarily reconducted to the Joule heating and very little attention has been dedicated to the [...] Read more.
In the past decade, a renewed interest on electromagnetic processing of materials has motivated several investigations on the interaction between matter, electric and magnetic fields. These effects are primarily reconducted to the Joule heating and very little attention has been dedicated to the magnetic field contributions. The magnetic field generated during electric current-assisted sintering has not been widely investigated. Magnetism could have significant effects on sintering as it generates significant magnetic forces, resulting in inductive electrical loads and preferential heating induced by overlapping magnetic fields (i.e., proximity effect). This work summarizes the magnetic field effects in electric current-assisted processing; it focuses on health and safety issues associated with large currents (up to 0.4 MA); using FEM simulations, it computes the self-generated magnetic field during spark plasma sintering (SPS) to consolidate materials with variable magnetic permeability; and it quantifies the Lorentz force acting at interparticle contact points. The results encourage one to pay more attention to magnetic field-related effects in order to engineer and exploit their potentials. Full article
(This article belongs to the Special Issue Spark Plasma Sintering of Metals and Metal Matrix Nanocomposites)
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Open AccessArticle
Microstructure Evolution and Mechanical Properties of Spark Plasma Sintered Manganese Addition on Ti-48Al-2Cr-2Nb Alloys
Metals 2020, 10(12), 1577; https://doi.org/10.3390/met10121577 - 25 Nov 2020
Abstract
Titanium aluminide (TiAl) is one of the most promising materials for aerospace applications. It is a suitable replacement for nickel-based superalloys predominantly used in these applications. Titanium aluminide with superior processability is the main task in carrying out this work. A less brittle [...] Read more.
Titanium aluminide (TiAl) is one of the most promising materials for aerospace applications. It is a suitable replacement for nickel-based superalloys predominantly used in these applications. Titanium aluminide with superior processability is the main task in carrying out this work. A less brittle TiAl alloy was fabricated using spark plasma sintering by adding the nominal composition (2.5, 5, and 7.5 wt.%) of manganese (Mn) to Ti-48Al-2Cr-2Nb. The samples were sintered at 1150 °C using spark plasma sintering (SPS), which helped produce highly dense models with fine grain sizes at the high heating rate (here, 100 °C per minute). The effects produced by Mn additions on the densification, mechanical properties (yield strength, hardness, and % elongation), and microstructure of the Ti aluminide alloys are studied. Scanning electron microscopy (SEM) has been used to explore the sintered samples’ microstructures. The alloyed materials are entirely dissolved in the gamma matrix due to the manganese approaching its melting point. XRD and SEM analysis confirmed the new intermetallic related to Mn neither with titanium nor aluminum. The enhancement of % elongation at break is evident for the little improvement in the ductility of TiAl by the addition of Mn. The samples’ tensile fracture nature is also evidence for enhancement in the alloy’s % elongation. Full article
(This article belongs to the Special Issue Spark Plasma Sintering of Metals and Metal Matrix Nanocomposites)
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Open AccessArticle
Development of New 14 Cr ODS Steels by Using New Oxides Formers and B as an Inhibitor of the Grain Growth
Metals 2020, 10(10), 1344; https://doi.org/10.3390/met10101344 - 08 Oct 2020
Abstract
In this work, new oxide dispersion strengthened (ODS) ferritic steels have been produced by powder metallurgy using an alternative processing route and characterized afterwards by comparing them with a base ODS steel with Y2O3 and Ti additions. Different alloying elements [...] Read more.
In this work, new oxide dispersion strengthened (ODS) ferritic steels have been produced by powder metallurgy using an alternative processing route and characterized afterwards by comparing them with a base ODS steel with Y2O3 and Ti additions. Different alloying elements like boron (B), which is known as an inhibitor of grain growth obtained by pinning grain boundaries, and complex oxide compounds (Y-Ti-Zr-O) have been introduced to the 14Cr prealloyed powder by using mechanical alloying (MA) and were further consolidated by spark employing plasma sintering (SPS). Techniques such as x-ray diffraction (XRD), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) were used to study the obtained microstructures. Micro-tensile tests and microhardness measurements were carried out at room temperature to analyze the mechanical properties of the differently developed microstructures, which was considered to result in a better strength in the ODS steels containing the complex oxide Y-Ti-Zr-O. In addition, small punch (SP) tests were performed to evaluate the response of the material under high temperatures conditions, under which promising mechanical properties were attained by the materials containing Y-Ti-Zr-O (14Al-X-ODS and 14Al-X-ODS-B) in comparison with the other commercial steel, GETMAT. The differences in mechanical strength can be attributed to the precipitate’s density, nature, size, and to the density of dislocations in each ODS steel. Full article
(This article belongs to the Special Issue Spark Plasma Sintering of Metals and Metal Matrix Nanocomposites)
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Open AccessArticle
Spark Plasma Sintering and Characterization of Al-TiB2 Composites
Metals 2020, 10(9), 1110; https://doi.org/10.3390/met10091110 - 19 Aug 2020
Cited by 1
Abstract
In this study, Al-TiB2 compacts fabricated by spark plasma sintering methods at different temperatures were characterized for densification, microstructural development, and mechanical properties. Sintering parameters used were temperatures of 500 °C and 550 °C under the pressure of 30 MPa. A very [...] Read more.
In this study, Al-TiB2 compacts fabricated by spark plasma sintering methods at different temperatures were characterized for densification, microstructural development, and mechanical properties. Sintering parameters used were temperatures of 500 °C and 550 °C under the pressure of 30 MPa. A very dense microstructure with uniform phase distribution and porosity was produced in the sample sintered at 550 °C with 2.5 wt% TiB2. The same sample exhibited excellent hardness value, and a high-tensile strength attributed to full metallurgical bonding, presence of sub-micron sized grains, and their uniform distribution. These results show that the TiB2 addition enhanced the composite’s hardness, sintered density, and tensile strength. In all the sintered samples, the fractographs revealed a mixed-mode fracture (ductile and brittle). Full article
(This article belongs to the Special Issue Spark Plasma Sintering of Metals and Metal Matrix Nanocomposites)
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Open AccessArticle
The Effect of the Processing Parameters on the Properties of the Liquid Phase Spark Plasma Sintered 80Fe-20(Al + MWCNT) Magnetic Metal Matrix Nanocomposites
Metals 2020, 10(7), 962; https://doi.org/10.3390/met10070962 - 16 Jul 2020
Abstract
In this paper, the liquid phase sintering was performed using spark plasma sintering to produce iron (Fe: 80 vol%)–aluminum (Al)–multi-walled carbon nanotubes (MWCNTs) magnetic hybrid metal matrix nanocomposites. The properties of the nanocomposites were investigated by considering different parameters of materials processing. The [...] Read more.
In this paper, the liquid phase sintering was performed using spark plasma sintering to produce iron (Fe: 80 vol%)–aluminum (Al)–multi-walled carbon nanotubes (MWCNTs) magnetic hybrid metal matrix nanocomposites. The properties of the nanocomposites were investigated by considering different parameters of materials processing. The reinforcement of MWCNT with a content of 0–2 vol% did not affect the saturation magnetization of the nanocomposites but increased the coercivity and reduced both the electrical resistivity and the mechanical transverse rupture strength. It was found that milling the powders for 24 h resulted in composite with high saturation magnetization (148.820 A·m2/kg) and high coercivity (2175.6 A/m) but further milling time had reduced the values of magnetic properties. The mixture of Fe nanoparticles and Fe microparticles in composites with a nanoparticles-to-microparticles volume ratio of 1:1 has led to the enhanced saturation magnetization up to 157.820 A·m2/kg and reduced the coercivity of 50.20% in comparison with the Fe nanoparticles based nanocomposites. That mixture exhibited good electrical resistivity but caused the reduction of mechanical strength. The post-sintering annealing has significantly improved the magnetic softness of the composites by reducing the coercivity up to 854.30 A/m and increased the saturation magnetization. Full article
(This article belongs to the Special Issue Spark Plasma Sintering of Metals and Metal Matrix Nanocomposites)
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Open AccessArticle
Effect of Small Variations in Zr Content on the Microstructure and Properties of Ferritic ODS Steels Consolidated by SPS
Metals 2020, 10(3), 348; https://doi.org/10.3390/met10030348 - 06 Mar 2020
Cited by 3
Abstract
Two different zirconium contents (0.45 and 0.60 wt.%) have been incorporated into a Fe-14Cr-5Al-3W-0.4Ti-0.25Y2O3 oxide dispersion-strengthened (ODS) steel in order to evaluate their effect on the final microstructure and mechanical properties. The powders with the targeted compositions were obtained by [...] Read more.
Two different zirconium contents (0.45 and 0.60 wt.%) have been incorporated into a Fe-14Cr-5Al-3W-0.4Ti-0.25Y2O3 oxide dispersion-strengthened (ODS) steel in order to evaluate their effect on the final microstructure and mechanical properties. The powders with the targeted compositions were obtained by mechanical alloying (MA), and subsequently processed by spark plasma sintering (SPS) at two different heating rates: 100 and 400 °C·min−1. Non-textured bimodal microstructures composed of micrometric and ultrafine grains were obtained. The increase in Zr content led to a higher percentage of Zr nano-oxides and larger regions of ultrafine grains. These ultrafine grains also seem to be promoted by higher heating rates. The effective pinning of the dislocations by the Zr dispersoids, and the refining of the microstructure, have significantly increased the strength exhibited by the ODS steels during the small punch tests, even at high temperatures (500 °C). Full article
(This article belongs to the Special Issue Spark Plasma Sintering of Metals and Metal Matrix Nanocomposites)
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