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Powder Metallurgy: Materials and Processing

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Metals and Alloys".

Deadline for manuscript submissions: closed (10 March 2023) | Viewed by 34344

Special Issue Editors

Dr. Dina V. Dudina

E-Mail Website
Guest Editor
Lavrentyev Institute of Hydrodynamics, Siberian Branch of the Russian Academy of Sciences, Lavrentyev Ave. 15, 630090 Novosibirsk, Russia
Interests: powder metallurgy; field-assisted sintering; metal matrix composites; powder processing; thermal spraying
Special Issues, Collections and Topics in MDPI journals
Dr. Arina V. Ukhina

E-Mail Website
Guest Editor
Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, Kutateladze str. 18, 630090 Novosibirks, Russia
Interests: sintering; hot pressing; surface modification; metal–diamond composites; characterization of materials by X-ray diffraction
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

We would like to invite submissions to a Special Issue of Materials titled “Powder Metallurgy: Materials and Processing”, the focus of which is the fundamental and applied aspects of materials fabrication by powder metallurgy.

Powder metallurgy has a long and interesting history. The Egyptian iron artefacts were fabricated through a re-carburization process: iron oxide was heated in a reducing fire (charcoal), then iron agglomerates were shaped into dense objects by hot hammering and reheated to induce the interaction with carbon and form steel. In India, both metal powder fabrication and sintering were established by 400 AD. In the 19th century, the production of platinum by powder metallurgy was realized thanks to research conducted by P. G. Sobolevskii and W. H. Wollaston. The fabrication of malleable platinum was described by Sobolevskii in Gornyi Zhurnal (Mining Journal) in 1827. The essence of the process was in the pressing of the platinum sponge into disks followed by their heating under pressure. In 1908, Coolidge developed a long-lasting ductile tungsten filament. It was formed by direct-current sintering of a pressed powder followed by hot working and drawing into a wire.

The powder metallurgy routes offer flexibility for the materials microstructure design, as, during sintering, the major fraction of the material remains in the solid state. At present, with the availability of modern technological equipment and powerful analytical tools, in-depth investigations of the material formation mechanisms operating during sintering are possible. A wide range of materials, including alloys and composites, are currently produced by powder metallurgy to achieve new levels of properties and performance.

The topics to be covered in this Issue include, but are not limited to:

  • Selection of sintering parameters for achieving desired microstructures and properties;
  • Microstructure formation mechanisms in sintered materials, including reactively sintered materials;
  • The influence of the powder morphology and microstructure on their sintering behavior;
  • Characterization of interfaces in sintered materials;
  • Sintered metals, alloys, and composites with attractive mechanical and thermophysical properties;
  • Structural and functional materials produced by powder metallurgy—new approaches to microstructure control;
  • Advanced sintering methods, including spark plasma sintering;
  • Comparative investigations of materials obtained by different powder sintering/consolidation methods.

We hope to receive high-quality articles, communications, and reviews reporting advancements in the fascinating field of powder metallurgy.

Sincerely yours,

Dr. Dina Dudina
Dr. Arina V. Ukhina
Guest Editors

Manuscript Submission Information

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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 semimonthly 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 2600 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

  • powder metallurgy
  • conventional sintering
  • spark plasma sintering
  • hot pressing
  • microstructure
  • grain growth
  • interface
  • grain boundary
  • metals
  • alloys
  • composites

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Editorial

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3 pages, 187 KiB  
Editorial
Powder Metallurgy: Materials and Processing
by Dina V. Dudina and Arina V. Ukhina
Materials 2023, 16(13), 4575; https://doi.org/10.3390/ma16134575 - 25 Jun 2023
Viewed by 1183
Abstract
This Special Issue (SI) of Materials, “Powder Metallurgy: Materials and Processing”, focuses on the fundamental and applied aspects of materials fabrication by powder metallurgy [...] Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)

Research

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14 pages, 3421 KiB  
Article
Combustion Synthesis of Magnesium-Aluminum Oxynitride MgAlON with Tunable Composition
by Tigran Akopdzhanyan, Danil Abzalov, Dmitry Moskovskikh, Mohammad Abedi and Valentin Romanovski
Materials 2023, 16(10), 3648; https://doi.org/10.3390/ma16103648 - 10 May 2023
Cited by 5 | Viewed by 1470
Abstract
Magnesium-aluminum oxynitride MgAlON has garnered significant attention in recent years due to its unique properties and potential applications. Herein, we report a systematic study on the synthesis of MgAlON with tunable composition by employing the combustion method. The Al/Al2O3/MgO [...] Read more.
Magnesium-aluminum oxynitride MgAlON has garnered significant attention in recent years due to its unique properties and potential applications. Herein, we report a systematic study on the synthesis of MgAlON with tunable composition by employing the combustion method. The Al/Al2O3/MgO mixture was combusted in nitrogen gas, and the effects of Al nitriding and oxidation by Mg(ClO4)2 on the exothermicity of the mixture, combustion kinetics, and phase composition of combustion products were investigated. Our results demonstrate that the MgAlON lattice parameter can be controlled by varying the AlON/MgAl2O4 ratio in the mixture, which corresponds to the MgO content in the combustion products. This work provides a new pathway for tailoring the properties of MgAlON, which may have significant implications in various technological applications. In particular, we reveal the dependence of the MgAlON lattice parameter on the AlON/MgAl2O4 ratio. The limitation of the combustion temperature by 1650 °C resulted in obtaining submicron powders with a specific surface area of about 3.8 m/g2. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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15 pages, 2304 KiB  
Article
Fabrication and Arc Erosion Behavior of Ag-SnO2-ZnO Electrical Contact Materials
by Danny Guzmán, Felipe González, Diego Muranda, Claudio Aguilar, Alexis Guzmán, Álvaro Soliz, Lorena Lozada, Iñigo Iturriza and Felipe Castro
Materials 2023, 16(10), 3618; https://doi.org/10.3390/ma16103618 - 9 May 2023
Cited by 11 | Viewed by 2439
Abstract
This study investigated the synthesis of Ag-SnO2-ZnO by powder metallurgy methods and their subsequent electrical contact behavior. The pieces of Ag-SnO2-ZnO were prepared by ball milling and hot pressing. The arc erosion behavior of the material was evaluated using [...] Read more.
This study investigated the synthesis of Ag-SnO2-ZnO by powder metallurgy methods and their subsequent electrical contact behavior. The pieces of Ag-SnO2-ZnO were prepared by ball milling and hot pressing. The arc erosion behavior of the material was evaluated using homemade equipment. The microstructure and phase evolution of the materials were investigated through X-ray diffraction, energy-dispersive spectroscopy and scanning electron microscopy. The results showed that, although the mass loss of the Ag-SnO2-ZnO composite (9.08 mg) during the electrical contact test was higher than that of the commercial Ag-CdO (1.42 mg), its electrical conductivity remained constant (26.9 ± 1.5% IACS). This fact would be related to the reaction of Zn2SnO4’s formation on the material’s surface via electric arc. This reaction would play an important role in controlling the surface segregation and subsequent loss of electrical conductivity of this type of composite, thus enabling the development of a new electrical contact material to replace the non-environmentally friendly Ag-CdO composite. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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15 pages, 11064 KiB  
Article
Influence of Sintering Atmosphere, Temperature and the Solution-Annealing Treatment on the Properties of Precipitation-Hardening Sintered 17-4 PH Stainless Steel
by Jan Kazior
Materials 2023, 16(2), 760; https://doi.org/10.3390/ma16020760 - 12 Jan 2023
Cited by 6 | Viewed by 2717
Abstract
So far, unlike metal injection molding (MIM), conventional powder metallurgy technology (PM) has not been regarded as a method for producing structural elements from 17-4 PH powders, due to the problems of obtaining almost fully compacted shapes after sintering. Nevertheless, recent research demonstrates [...] Read more.
So far, unlike metal injection molding (MIM), conventional powder metallurgy technology (PM) has not been regarded as a method for producing structural elements from 17-4 PH powders, due to the problems of obtaining almost fully compacted shapes after sintering. Nevertheless, recent research demonstrates that it is possible to manufacture sintered parts with high strength by pressing and sintering. The purpose of the study was to determine the degree of densification of 17-4 PH sintered stainless steel during sintering at different temperatures and atmospheres. As a result of the study, it was pointed out that both the temperature and the sintering atmosphere play an essential role in the process of densification of the studied powders during sintering. The formation of delta ferrite and a more pronounced degree of spheroidization of the pores is activated by a higher sintering temperature. Furthermore, after solution-annealed and age-hardened treatment, sintered 17-4 PH stainless steel exhibits high strength with moderate ductility at a level that is difficult to achieve for other sintered stainless-steel grades, such as austenitic, ferritic and martensitic. In turn, the largest improvement in the pitting corrosion resistance in 0.5 M NaCl solution is reached by sintering at 1340 °C in hydrogen and after solid solution treatment. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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16 pages, 8155 KiB  
Article
Evolution of the Microstructure and Phase Composition of the Products Formed in the Reaction between Iridium and W2B
by Denis A. Bannykh, Victor V. Lozanov, Tatyana A. Gavrilova, Anatoly I. Beskrovny and Natalya I. Baklanova
Materials 2022, 15(21), 7522; https://doi.org/10.3390/ma15217522 - 26 Oct 2022
Cited by 2 | Viewed by 1375
Abstract
In the present study, we perform a systematic examination of the products formed by mixing and heating of tungsten boride and iridium powders at different ratios in a broad temperature range using qualitative and quantitative X-ray analysis and time-of-flight neutron diffraction (TOF-ND), in [...] Read more.
In the present study, we perform a systematic examination of the products formed by mixing and heating of tungsten boride and iridium powders at different ratios in a broad temperature range using qualitative and quantitative X-ray analysis and time-of-flight neutron diffraction (TOF-ND), in combination with scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS) performed at different accelerating voltages. The well-known and unknown ternary W–Ir–B phases were detected. The Vickers microhardness value for the new ternary W2Ir5B2 boride was measured. Based on these findings, the ternary W2Ir5B2 boride can be considered hard. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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13 pages, 5101 KiB  
Communication
Cyclic Impact Compaction of an Ultra High Molecular Weight Polyethylene (UHMWPE) Powder and Properties of the Compacts
by Alexandr Shtertser, Boris Zlobin, Victor Kiselev, Sergei Shemelin, Arina Ukhina and Dina Dudina
Materials 2022, 15(19), 6706; https://doi.org/10.3390/ma15196706 - 27 Sep 2022
Cited by 4 | Viewed by 1623
Abstract
Experiments on Cyclic Impact Compaction (CIC) of UHMWPE powder GUR 4120 were carried out on a laboratory hydro-pneumatic impact device. This device provides impact energies of up to 1 kJ with a frequency of impacts of 9 s−1 and enables producing dense [...] Read more.
Experiments on Cyclic Impact Compaction (CIC) of UHMWPE powder GUR 4120 were carried out on a laboratory hydro-pneumatic impact device. This device provides impact energies of up to 1 kJ with a frequency of impacts of 9 s−1 and enables producing dense and robust compacts in the form of disks with a diameter of up to 60 mm and a height of up to 24 mm. The optimal parameters of the CIC were determined, which are the preheating temperature of the powder, the impact energy and the number of impacts. The strength, Brinell hardness and elongation of the resulting compacts with a diameter of 40 mm and a height of 15 mm were 37.5 MPa, 49.0 MPa and 470%, respectively. The possibility of activating UHMWPE powder by explosive loading was studied. It was found that the explosive pretreatment reduces the mechanical properties of the resultant compacts. The CIC method is suitable for the manufacture of UHMWPE-based composites with nano-additives, as evidenced by the successful production of compacts containing nanoscale detonation carbon as an additive. The results of the present study show that the CIC method is promising for the industrial production of small-sized UHMWPE parts. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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16 pages, 5696 KiB  
Article
Preparation and Study of Composite Materials of the NiAl-Cr-Mo-Nanoparticles (ZrO2, MgAl2O4) System
by Leonid Agureev, Valeriy Kostikov, Svetlana Savushkina, Zhanna Eremeeva and Maxim Lyakhovetsky
Materials 2022, 15(17), 5822; https://doi.org/10.3390/ma15175822 - 24 Aug 2022
Cited by 2 | Viewed by 1438
Abstract
Materials based on the NiAl-Cr-Mo system with zirconium oxide or aluminum-magnesium spinel nanoparticle small additions were obtained by spark plasma sintering. Thermodynamic modeling was carried out to predict the phase formation in the NiAl-Cr-Mo system and its change depending on temperature, considering the [...] Read more.
Materials based on the NiAl-Cr-Mo system with zirconium oxide or aluminum-magnesium spinel nanoparticle small additions were obtained by spark plasma sintering. Thermodynamic modeling was carried out to predict the phase formation in the NiAl-Cr-Mo system and its change depending on temperature, considering the presence of a small amount of carbon in the system. The phase composition and microstructure of materials were studied. NiAl (B2) and CrMo phases were found in the sintered samples. Bending strength measurements at different temperatures shows that nanoparticles of insoluble additives lead to an increase in bending strength, especially at high temperatures. A fractographic analysis of the sample’s fractures shows their hybrid nature and intercrystalline fracture, which is confirmed by the clearly visible matrix grains similar to cleavage. The maximum strength at 700 °C (475 MPa) was found for material with the addition of 0.1 wt.% zirconium oxide nanoparticles. In the study of internal friction, typical peaks of a nickel-aluminum alloy were found in the temperature ranges of 150–200 °C and 350–400 °C. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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11 pages, 6325 KiB  
Article
Elaboration and Characterization of WMoTaNb High Entropy Alloy Prepared by Powder Metallurgy Processes
by Mathias Moser, Sarah Dine, Dominique Vrel, Loïc Perrière, Rémy Pirès-Brazuna, Hervé Couque and Frédéric Bernard
Materials 2022, 15(15), 5416; https://doi.org/10.3390/ma15155416 - 5 Aug 2022
Cited by 4 | Viewed by 2087
Abstract
This work concerns the sintering of tungsten-based (i.e WMoTaNb) high entropy alloy (HEA) powders using the spark plasma sintering (SPS) technique and their mechanical properties. The synthesis was performed by a self-propagating high-temperature synthesis (SHS) type reaction in which the mixture of metallic [...] Read more.
This work concerns the sintering of tungsten-based (i.e WMoTaNb) high entropy alloy (HEA) powders using the spark plasma sintering (SPS) technique and their mechanical properties. The synthesis was performed by a self-propagating high-temperature synthesis (SHS) type reaction in which the mixture of metallic oxides (WO3, MoO3 …) is reduced by magnesium. For this, a specific reactor has been developed. Different conditions including the addition of a moderator were tested. These powders are then densified by SPS technology which allows for keeping the initial microstructure of the powder. The optimization of sintering conditions was performed with the objective to control simultaneously the chemical composition, the grain growth and the densification stages. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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11 pages, 1387 KiB  
Article
On the Sintering Behavior of Nb2O5 and Ta2O5 Mixed Oxide Powders
by Maureen P. Chorney, Kunal Mondal, Jerome P. Downey and Prabhat K. Tripathy
Materials 2022, 15(14), 5036; https://doi.org/10.3390/ma15145036 - 20 Jul 2022
Cited by 1 | Viewed by 1826
Abstract
A mixed oxide system consisting of Nb2O5 and Ta2O5, was subjected to annealing in air/hydrogen up to 950 °C for 1–4 h to study its sintering behavior. The thermogravimetric–differential scanning calorimetry (TGA–DSC) thermograms indicated the formation of [...] Read more.
A mixed oxide system consisting of Nb2O5 and Ta2O5, was subjected to annealing in air/hydrogen up to 950 °C for 1–4 h to study its sintering behavior. The thermogravimetric–differential scanning calorimetry (TGA–DSC) thermograms indicated the formation of multiple endothermic peaks at temperatures higher than 925 °C. Subsequently, a 30% Ta2O5 and 70% Nb2O5 (mol%) pellet resulted in good sintering behavior at both 900 and 950 °C. The scanning electron microscope (SEM) images corroborated these observations with necking and particle coarsening. The sintered pellets contained a 20.4 and 20.8% mixed oxide (Nb4Ta2O15) phase, along with Ta2O5 and Nb2O5, at both 900 and 950 °C, indicating the possibility of the formation of a solid solution phase. In situ high-temperature X-ray diffraction (XRD) scans also confirmed the formation of the ternary oxide phase at 6 and 19.8% at 890 and 950 °C, respectively. The Hume–Rothery rules could explain the good sintering behavior of the Ta2O5 and Nb2O5 mixed oxides. An oxide composition of 30% Ta2O5 and 70% Nb2O5 (mol%) and a sintering temperature of 950 °C appeared adequate for fabricating well-sintered oxide precursors for subsequent electrochemical polarization studies in fused salts. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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13 pages, 5266 KiB  
Article
A Feasibility Study of High-Entropy Alloy Coating Deposition by Detonation Spraying Combined with Laser Melting
by Igor S. Batraev, Vladimir Yu. Ulianitsky, Alexey A. Sova, Marina N. Samodurova, Evgeny A. Trofimov, Kirill Yu. Pashkeev, Alexander G. Malikov, Dina V. Dudina and Arina V. Ukhina
Materials 2022, 15(13), 4532; https://doi.org/10.3390/ma15134532 - 27 Jun 2022
Cited by 9 | Viewed by 1957
Abstract
In this work, a new two-stage approach to the deposition of high-entropy alloy coatings is proposed. At the first stage, a composite precursor coating is formed by detonation spraying of the metal powder mixtures. At the second stage, the precursor coating is re-melted [...] Read more.
In this work, a new two-stage approach to the deposition of high-entropy alloy coatings is proposed. At the first stage, a composite precursor coating is formed by detonation spraying of the metal powder mixtures. At the second stage, the precursor coating is re-melted by a laser, and the formation of multi-component solid solution phases can be expected upon solidification. The feasibility of the proposed approach was validated using three different mixtures of Fe, Ni, Cu, Co and Al powders. It was shown that detonation spraying allows forming composite coatings with a uniform distribution of the lamellae of different metals. The results of the structural analysis of the laser-treated coatings suggest that complete alloying occurred in the melt and face-centered cubic solid solutions formed in the coatings upon cooling. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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23 pages, 8135 KiB  
Article
The Influence of Nanographite Addition on the Compaction Process and Properties of AISI 316L Sintered Stainless Steel
by Barbara Kozub, Marimuthu Uthayakumar and Jan Kazior
Materials 2022, 15(10), 3629; https://doi.org/10.3390/ma15103629 - 19 May 2022
Cited by 3 | Viewed by 1481
Abstract
This paper presents the effect of graphite addition on the pressing process and selected mechanical properties of AISI 316L austenitic stainless steel. The graphite powders used in this study differed in the value of the specific surface area of the particles, which were [...] Read more.
This paper presents the effect of graphite addition on the pressing process and selected mechanical properties of AISI 316L austenitic stainless steel. The graphite powders used in this study differed in the value of the specific surface area of the particles, which were 15 (micropowder), 350, and 400 m2/g (nanopowder). Mixtures with the addition of lubricants—stearic acid and Kenolube—were also created, for comparison purposes. The scope of the tests included compressibility of blends, measurements of the ejection force while removing the compacts from the die, micro-structural studies, a static tensile test, a three-point bending test, a Kc impact test, Rockwell hardness, and Vickers microhardness measurements. The study demonstrated that the addition of graphite nanopowder to the studied steel acts as a lubricant, providing a significant improvement in lubricity during the pressing process. Moreover, the addition of nanographite allowed for a significant increase in the mechanical properties studied in this work; it was observed that, for the sinters made of mixtures with a higher graphite content and with a large specific surface area of its particles, better values for the tested properties were obtained. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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15 pages, 5871 KiB  
Article
Morphological and Structural Transformations of Fe-Pd Powder Alloys Formed by Galvanic Replacement, Annealing and Acid Treatment
by Sergey A. Petrov, Dina V. Dudina, Arina V. Ukhina and Boris B. Bokhonov
Materials 2022, 15(10), 3571; https://doi.org/10.3390/ma15103571 - 17 May 2022
Cited by 4 | Viewed by 1805
Abstract
In this article, we report the preparation and structural features of Fe-Pd powder alloys formed by galvanic replacement, annealing and selective dissolution of iron via acid treatment. The alloys were studied by the X-ray diffraction phase analysis, Mössbauer spectroscopy, scanning electron microscopy, and [...] Read more.
In this article, we report the preparation and structural features of Fe-Pd powder alloys formed by galvanic replacement, annealing and selective dissolution of iron via acid treatment. The alloys were studied by the X-ray diffraction phase analysis, Mössbauer spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy. The Fe@Pd core–shell particles were obtained by a galvanic replacement reaction occurring upon treatment of a body-centered cubic (bcc) iron powder by a solution containing PdCl42− ions. It was found that the shells are a face-centered cubic (fcc) Pd(Fe) solid solution. HCl acid treatment of the Fe@Pd core–shell particles resulted in the formation of hollow Pd-based particles, as the bcc phase was selectively dissolved from the cores. Annealing of the Fe@Pd core–shell particles at 800 °C led to the formation of fcc Fe-Pd solid solution. Acid treatment of the Fe-Pd alloys formed by annealing of the core–shell particles allowed selectively dissolving iron from the bcc Fe-based phase (Fe(Pd) solid solution), while the fcc Fe-rich Fe-Pd solid solution remained stable (resistant to acid corrosion). It was demonstrated that the phase composition and the Fe/Pd ratio in the alloys (phases) can be tailored by applying annealing and/or acid treatment to the as-synthesized Fe@Pd core–shell particles. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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12 pages, 5466 KiB  
Article
Heat Treatment Influencing Porosity and Tensile Properties of Field Assisted Sintered AlSi7Mg0.6
by Sarah Johanna Hirsch, Lisa Winter, Thomas Grund and Thomas Lampke
Materials 2022, 15(7), 2503; https://doi.org/10.3390/ma15072503 - 29 Mar 2022
Cited by 9 | Viewed by 2195
Abstract
In this study, an attempt was made to improve the mechanical properties and in particular the strength of a precipitation-hardenable aluminum alloy while still maintaining high ductility. For this purpose, AlSi7Mg0.6 (A357) powder with an average particle diameter of d50 = 40 [...] Read more.
In this study, an attempt was made to improve the mechanical properties and in particular the strength of a precipitation-hardenable aluminum alloy while still maintaining high ductility. For this purpose, AlSi7Mg0.6 (A357) powder with an average particle diameter of d50 = 40 µm was consolidated using field assisted sintering technique (FAST), and two material conditions were compared: an as-sintered and an underaging heat treated condition (T61). Mechanical properties were determined using tensile tests and hardness measurements. In addition, the microstructure was investigated by optical microscopy. Further, porosity and density were analyzed after the different heat treatments. By the underaging heat treatment, the surface hardness was increased by 100% and the yield strength was increased by 80% compared to the as-sintered material. However, the elongation to failure dropped to one third of that of the as-sintered material. Presumably, this effect was a result of an increased porosity due to the heat treatment. It is assumed that the observed pores were generated by artefacts from the FAST process used to manufacture the samples. The internal gas pressure and equilibrium diffusion supported by heat treatment temperature, and the reduction in surface energy caused by coalescent micropores, led to the enlargement of previously undetectable inhomogeneities in the as-sintered material that resulted in pores in the heat-treated sintered alloy. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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16 pages, 4042 KiB  
Article
Elimination of Composition Segregation in 33Al–45Cu–22Fe (at.%) Powder by Two-Stage High-Energy Mechanical Alloying
by Serguei Tikhov, Konstantin Valeev, Svetlana Cherepanova, Vladimir Zaikovskii, Aleksei Salanov, Vladislav Sadykov, Dina Dudina, Oleg Lomovsky, Sergey Petrov, Oleg Smorygo and Amol Gokhale
Materials 2022, 15(6), 2087; https://doi.org/10.3390/ma15062087 - 11 Mar 2022
Cited by 7 | Viewed by 2066
Abstract
In the present work, complex powder alloys containing spinel as a minor phase were produced by mechanical alloying in a high-energy planetary ball mill from a 33Al–45Cu–22Fe (at.%) powder blend. These alloys show characteristics suitable for the synthesis of promising catalysts. The alloying [...] Read more.
In the present work, complex powder alloys containing spinel as a minor phase were produced by mechanical alloying in a high-energy planetary ball mill from a 33Al–45Cu–22Fe (at.%) powder blend. These alloys show characteristics suitable for the synthesis of promising catalysts. The alloying was conducted in two stages: at the first stage, a Cu+Fe powder mixture was ball-milled for 90 min; at the second stage, Al was added, and the milling process was continued for another 24 min. The main products of mechanical alloying formed at each stage were studied using X-ray diffraction phase analysis, Mössbauer spectroscopy, transmission electron microscopy, and energy-dispersive spectroscopy. At the end of the first stage, crystalline iron was not found. The main product of the first stage was a metastable Cu(Fe) solid solution with a face-centered cubic structure. At the second stage, the Cu(Fe) solid solution transformed to Cu(Al), several Fe-containing amorphous phases, and a spinel phase. The products of the two-stage process were different from those of the single-stage mechanical alloying of the ternary elemental powder mixture; the formation of undesirable intermediate phases was avoided, which ensured excellent composition uniformity. A sequence of solid-state reactions occurring during mechanical alloying was proposed. Mesopores and a spinel phase were the features of the two-stage milled material (both are desirable for the target catalyst). Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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10 pages, 6702 KiB  
Article
In Situ Ti6Al4V/TiB Composites Prepared by Hydrogen-Assisted Sintering of Blends Containing TiH2 and Ball-Milled Ti+TiB2 Powders
by Yuchao Song, Fucheng Qiu, Dmytro Savvakin, Xiaofeng Xu, Oleksandr Stasiuk, Orest Ivasishin and Tuo Cheng
Materials 2022, 15(3), 1049; https://doi.org/10.3390/ma15031049 - 29 Jan 2022
Cited by 7 | Viewed by 1860
Abstract
In the present study, 98.6–99.5% dense in situ reinforced Ti6Al4V/TiB composites were manufactured with a newly developed approach based on hydrogen-assisted blended elemental powder metallurgy (BEPM). The approach includes the activation milling of titanium powder produced with hydrogenation-dehydrogenation (HDH-Ti powder) with finer TiB [...] Read more.
In the present study, 98.6–99.5% dense in situ reinforced Ti6Al4V/TiB composites were manufactured with a newly developed approach based on hydrogen-assisted blended elemental powder metallurgy (BEPM). The approach includes the activation milling of titanium powder produced with hydrogenation-dehydrogenation (HDH-Ti powder) with finer TiB2 additives, following blending with TiH2 and master alloy (MA) powders, and final press-and-sinter operations. Scanning electron microscope (SEM) observations prove the formation of microstructures with improved density and homogeneous distribution of TiB reinforcements in a sintered Ti6Al4V matrix. Hardness and compressive tests validated the high mechanical characteristics of produced composites. The effect of preliminary milling time over 2–6 h and the ratio of hydrogenated and non-hydrogenated titanium powders used (TiH2 vs. HDH Ti) on microstructure and mechanical properties were studied to further optimize the processing parameters. Test results indicate the above approach can be regarded as a promising route for the cost-effective manufacturing of Ti6Al4V/TiB composite with reduced porosity, tailored microstructure uniformity, acceptable impurity level and, hence, mechanical characteristics sufficient for practice applications. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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Review

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29 pages, 12644 KiB  
Review
Metallic Glass-Reinforced Metal Matrix Composites: Design, Interfaces and Properties
by Konstantinos Georgarakis, Dina V. Dudina and Vyacheslav I. Kvashnin
Materials 2022, 15(23), 8278; https://doi.org/10.3390/ma15238278 - 22 Nov 2022
Cited by 13 | Viewed by 2658
Abstract
When metals are modified by second-phase particles or fibers, metal matrix composites (MMCs) are formed. In general, for a given metallic matrix, reinforcements differing in their chemical nature and particle size/morphology can be suitable while providing different levels of strengthening. This article focuses [...] Read more.
When metals are modified by second-phase particles or fibers, metal matrix composites (MMCs) are formed. In general, for a given metallic matrix, reinforcements differing in their chemical nature and particle size/morphology can be suitable while providing different levels of strengthening. This article focuses on MMCs reinforced with metallic glasses and amorphous alloys, which are considered as alternatives to ceramic reinforcements. Early works on metallic glass (amorphous alloy)-reinforced MMCs were conducted in 1982–2005. In the following years, a large number of composites have been obtained and tested. Metallic glass (amorphous alloy)-reinforced MMCs have been obtained with matrices of Al and its alloys, Mg and its alloys, Ti alloys, W, Cu and its alloys, Ni, and Fe. Research has been extended to new compositions, new design approaches and fabrication methods, the chemical interaction of the metallic glass with the metal matrix, the influence of the reaction products on the properties of the composites, strengthening mechanisms, and the functional properties of the composites. These aspects are covered in the present review. Problems to be tackled in future research on metallic glass (amorphous alloy)-reinforced MMCs are also identified. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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Other

13 pages, 3139 KiB  
Viewpoint
Core–Shell Particle Reinforcements—A New Trend in the Design and Development of Metal Matrix Composites
by Dina V. Dudina and Konstantinos Georgarakis
Materials 2022, 15(7), 2629; https://doi.org/10.3390/ma15072629 - 2 Apr 2022
Cited by 10 | Viewed by 2671
Abstract
Metal matrix composites (MMCs) are a constantly developing class of materials. Simultaneously achieving a high strength and a high ductility is a challenging task in the design of MMCs. This article aims to highlight a recent trend: the development of MMCs reinforced with [...] Read more.
Metal matrix composites (MMCs) are a constantly developing class of materials. Simultaneously achieving a high strength and a high ductility is a challenging task in the design of MMCs. This article aims to highlight a recent trend: the development of MMCs reinforced with particles of core–shell structure. The core–shell particles can be synthesized in situ upon a partial transformation of metal (alloy) particles introduced into a metal matrix. MMCs containing core–shell particles with cores of different compositions (metallic, intermetallic, glassy alloy, high-entropy alloy, metal-ceramic) are currently studied. For metal core–intermetallic shell particle-reinforced composites, the property gain by the core–shell approach is strengthening achieved without a loss in ductility. The propagation of cracks formed in the brittle intermetallic shell is hindered by both the metal matrix and the metal core, which constitutes a key advantage of the metal core–intermetallic shell particles over monolithic particles of intermetallic compounds for reinforcing purposes. The challenges of making a direct comparison between the core–shell particle-reinforced MMCs and MMCs of other microstructures and future research directions are discussed. Full article
(This article belongs to the Special Issue Powder Metallurgy: Materials and Processing)
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