Metals

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16 pages, 14992 KiB

Open AccessArticle

Production of a Reinforced Refractory Multielement Alloy via High-Energy Ball Milling and Spark Plasma Sintering

by Cinzia Menapace, Khaja Naib Rasool Shaik, Lorena Emanuelli and Gloria Ischia

Metals 2023, 13(7), 1189; https://doi.org/10.3390/met13071189 - 27 Jun 2023

Cited by 1 | Viewed by 862

Refractory high entropy alloys have shown potential to be developed as structural materials for elevated temperature applications. In the present research, the multielement alloy Fe2TiVZrW0.5 was produced by high-energy ball milling of elemental powders in the air to promote the formation of reinforcing [...] Read more.

Refractory high entropy alloys have shown potential to be developed as structural materials for elevated temperature applications. In the present research, the multielement alloy Fe2TiVZrW0.5 was produced by high-energy ball milling of elemental powders in the air to promote the formation of reinforcing oxide and nitride particles followed by spark plasma sintering consolidation. The sintering temperature was optimized to achieve a full-density material that was characterized from the microstructural and mechanical points of view. Hardness and KIC were measured in the as-sintered condition as well as after thermal treatment at 1100 °C. TEM observations showed the presence of a fine distribution of ZrO₂ and Ti(V)-N in the microstructure mainly constituted by the bcc Fe-V and Fe-V-W phases. The fine distribution of ceramic particles in a metallic multielement matrix is responsible for the consistent hardness and thermal stability of this alloy. Full article

(This article belongs to the Special Issue High Energy Ball Milling and Consolidation of Nanocomposite Powders)

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14 pages, 4044 KiB

Open AccessArticle

Manufacturing of Novel Nanostructured TiCrC Carbides Using Mechanical Alloying and Spark Plasma Sintering

by Mohsen Mhadhbi, İlker Emin Dağ, Barış Avar, Mohamed Khitouni, Mohamed Ali Bousnina, Frédéric Schoenstein and Noureddine Jouini

Metals 2023, 13(6), 1040; https://doi.org/10.3390/met13061040 - 30 May 2023

Viewed by 1178

Abstract

Dense nanostructured carbides existing in ternary system Ti-Cr-C were elaborated thanks to a two-steps method. In the first step, nanostructured Ti_0.9Cr_0.1C carbides were prepared by high-energy planetary ball milling under various times (5, 10, and 20 h), starting from [...] Read more.

Dense nanostructured carbides existing in ternary system Ti-Cr-C were elaborated thanks to a two-steps method. In the first step, nanostructured Ti_0.9Cr_0.1C carbides were prepared by high-energy planetary ball milling under various times (5, 10, and 20 h), starting from an elemental powder mixture of titanium, chromium, and graphite. In the second step, these nanostructured powders were used to produce densified carbides thanks to the spark plasma sintering (SPS) process under a pressure of 80 MPa. The temperature was fixed at 1800 °C and the holding time was fixed at 5 min. Microstructural characteristics of the samples were investigated using X-ray diffraction (XRD). Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) was used to investigate the morphology and elemental composition of the samples obtained using SPS. The novelty of this work is to understand the effect of SPS on the microstructural and electrochemical properties of the nanostructured Ti_0.9Cr_0.1C carbides. The XRD results showed that, during sintering process, the (Ti,Cr)C carbide was decomposed into TiC, Cr₇C₃, and Cr₃C₂ phases. An amount of iron was detected as contamination during milling, especially in the case of a sample obtained from 20 h milled carbide. The bulk obtained from the milled powders for 5 and 20 h present similar relative densities of 98.43 and 98.51%, respectively. However, the 5 h milled sample shows slightly higher hardness (93.3 HRA compared to 91.5 HRA) because of the more homogeneous distribution of the (Ti,Cr)C phases and the low iron amount. According to the 0.0011 mm/year corrosion rate and 371.68 kΩ.cm² charge transfer resistance obtained from the potentiodynamic polarization and EIS tests, the 20 h carbide was the specimen with the highest corrosion resistance. Full article

(This article belongs to the Special Issue High Energy Ball Milling and Consolidation of Nanocomposite Powders)

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26 pages, 10243 KiB

Open AccessArticle

Development of Materials Based on the NiAlCrMoCo System Reinforced with ZrO₂ Nanoparticles

by Leonid Agureev, Svetlana Savushkina, Ivan Laptev, Elena Vysotina and Maxim Lyakhovetsky

Metals 2022, 12(12), 2014; https://doi.org/10.3390/met12122014 - 24 Nov 2022

Viewed by 1056

Abstract

This paper describes thermodynamic modeling of the NiAl–CrMoCo system with the calculation of the equilibrium composition and thermodynamic parameters of the system. NiAl-Cr-Mo-Co alloy samples of equiatomic composition, including those with a small addition of zirconium oxide nanoparticles, were obtained by spark plasma [...] Read more.

This paper describes thermodynamic modeling of the NiAl–CrMoCo system with the calculation of the equilibrium composition and thermodynamic parameters of the system. NiAl-Cr-Mo-Co alloy samples of equiatomic composition, including those with a small addition of zirconium oxide nanoparticles, were obtained by spark plasma sintering of mechanically alloyed powders. It was found that the material had a two-phase structure with wedge-shaped regions enriched in cobalt and molybdenum with a gradient distribution. In addition, in the regions enriched with (Cr, Mo) phase, a lamellar σ phase was found. Fractographic analysis showed a positive effect of the fine-grained wedge-shaped regions on the damping of crack propagation. The alloy with the addition of zirconium oxide nanoparticles had a bending strength and an elastic modulus of 611 MPa and 295 GPa at 25 °C, and 604 MPa and 260 GPa at 750 °C, respectively, when tested in vacuum. Full article

(This article belongs to the Special Issue High Energy Ball Milling and Consolidation of Nanocomposite Powders)

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10 pages, 2069 KiB

Open AccessArticle

Effect of Ball Size on the Microstructure and Morphology of Mg Powders Processed by High-Energy Ball Milling

by Jesus Rios, Alex Restrepo, Alejandro Zuleta, Francisco Bolívar, Juan Castaño, Esteban Correa and Félix Echeverria

Metals 2021, 11(10), 1621; https://doi.org/10.3390/met11101621 - 13 Oct 2021

Cited by 11 | Viewed by 3077

Abstract

Commercial powders of pure magnesium were processed by high-energy ball milling. The microstructural and morphological evolution of the powders was studied using scanning electron microscopy (SEM), energy dispersive spectrometry (EDX) and X-ray diffraction (XRD). From the results obtained, it was determined that the [...] Read more.

Commercial powders of pure magnesium were processed by high-energy ball milling. The microstructural and morphological evolution of the powders was studied using scanning electron microscopy (SEM), energy dispersive spectrometry (EDX) and X-ray diffraction (XRD). From the results obtained, it was determined that the ball size is the most influential milling parameter. This was because balls of 1 mm diameter were used after a previous stage of milling with larger balls (i.e., 10 and 3 mm). The powder particles presented an unusual morphology with respect to those observed in the Mg-milling literature and recrystallization phenomena. Moreover, the result strongly varied depending on the ball-to-powder weight ratio (BPR) used during the milling process. Full article

(This article belongs to the Special Issue High Energy Ball Milling and Consolidation of Nanocomposite Powders)

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13 pages, 2466 KiB

Open AccessArticle

Investigation of the Cause-Effect Relationships between the Exothermic Reaction and the Microstructures of Reactive Ni-Al Particles Produced by High Energy Planetary Ball Milling

by Christian Bernauer, Sandra Grohmann, Philipp Angermann, Daniel Dickes, Florian Holzberger, Pierre Amend and Michael F. Zaeh

Metals 2021, 11(6), 876; https://doi.org/10.3390/met11060876 - 27 May 2021

Cited by 4 | Viewed by 2099

Abstract

Reactive particles consisting of nickel and aluminum represent an adaptable heat source for joining applications, since each individual particle is capable of undergoing a self-sustaining exothermic reaction. Of particular interest are particles with intrinsic lamellar microstructures, as they provide large contact areas between [...] Read more.

Reactive particles consisting of nickel and aluminum represent an adaptable heat source for joining applications, since each individual particle is capable of undergoing a self-sustaining exothermic reaction. Of particular interest are particles with intrinsic lamellar microstructures, as they provide large contact areas between the reactants nickel and aluminum. In this work, the exothermic reaction as well as the microstructure of such lamellar reactive particles produced by high energy planetary ball milling were investigated. Based on statistically designed experiments regarding the milling parameters, the heat of reaction was examined by means of differential scanning calorimetry (DSC). A statistical model was derived from the results to predict the heat of reaction as a function of the milling parameters used. This model can be applied to adjust the heat of reaction of the reactive particles depending on the thermal properties of the joining partners. The fabricated microstructures were evaluated by means of scanning electron microscopy (SEM). Through the development of a dedicated SEM image evaluation algorithm, a computational quantification of the contact area between nickel and aluminum was enabled for the first time. A weak correlation between the contact area and the heat of reaction could be demonstrated. It is assumed that the quantification of the contact areas can be further improved by a higher number of SEM images per sample. The findings obtained provide an essential contribution to enable reactive particles as a tailored heat source for joining applications. Full article

(This article belongs to the Special Issue High Energy Ball Milling and Consolidation of Nanocomposite Powders)

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14 pages, 6945 KiB

Open AccessFeature PaperArticle

Influence of Alumina Nanofibers Sintered by the Spark Plasma Method on Nickel Mechanical Properties

by Leonid Agureev, Valeriy Kostikov, Zhanna Eremeeva, Svetlana Savushkina, Boris Ivanov, Dmitriy Khmelenin, Gleb Belov and Yuri Solyaev

Metals 2021, 11(4), 548; https://doi.org/10.3390/met11040548 - 28 Mar 2021

Cited by 2 | Viewed by 1857

Abstract

The article presents the study of alumina nanoparticles’ (nanofibers) concentration effect on the strength properties of pure nickel. The samples were obtained by spark plasma sintering of previously mechanically activated metal powders. The dependence of the grain size and the relative density of [...] Read more.

The article presents the study of alumina nanoparticles’ (nanofibers) concentration effect on the strength properties of pure nickel. The samples were obtained by spark plasma sintering of previously mechanically activated metal powders. The dependence of the grain size and the relative density of compacts on the number of nanofibers was investigated. It was found that with an increase in the concentration of nanofibers, the average size of the matrix particles decreased. The effects of the nanoparticle concentration (0.01–0.1 wt.%) on the elastic modulus and tensile strength were determined for materials at 25 °C, 400 °C, and 750 °C. It was shown that with an increase in the concentration of nanofibers, a 10–40% increase in the elastic modulus and ultimate tensile strength occurred. A comparison of the mechanical properties of nickel in a wide range of temperatures, obtained in this work with materials made by various technologies, is carried out. A description of nanofibers’ mechanisms of influence on the structure and mechanical properties of nickel is given. The possible impact of impurity phases on the properties of nickel is estimated. The tendency of changes in the mechanical properties of nickel, depending on the concentration of nanofibers, is shown. Full article

(This article belongs to the Special Issue High Energy Ball Milling and Consolidation of Nanocomposite Powders)

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16 pages, 4071 KiB

Open AccessArticle

Comparison of Conventional and Flash Spark Plasma Sintering of Cu–Cr Pseudo-Alloys: Kinetics, Structure, Properties

by Kirill V. Kuskov, Mohammad Abedi, Dmitry O. Moskovskikh, Illia Serhiienko and Alexander S. Mukasyan

Metals 2021, 11(1), 141; https://doi.org/10.3390/met11010141 - 12 Jan 2021

Cited by 22 | Viewed by 2485

Abstract

Spark plasma sintering (SPS) is widely used for the consolidation of different materials. Copper-based pseudo alloys have found a variety of applications including as electrodes in vacuum interrupters of high-voltage electric circuits. How does the kinetics of SPS consolidation for such alloys depend [...] Read more.

Spark plasma sintering (SPS) is widely used for the consolidation of different materials. Copper-based pseudo alloys have found a variety of applications including as electrodes in vacuum interrupters of high-voltage electric circuits. How does the kinetics of SPS consolidation for such alloys depend on the heating rate? Do SPS kinetics depend on the microstructure of the media to be sintered? These questions were addressed by the investigation of SPS kinetics in the heating rate range of 0.1 to 50 K/s. The latter conditions were achieved through flash spark plasma sintering (FSPS). We also compared the sintering kinetics for the conventional copper–chromium mixture and for the mechanically induced copper/chromium nanostructured particles. It was shown that, under FSPS conditions, the observed maximum consolidation rates were 20–30 times higher than that for conventional SPS with a heating rate of 100 K/min. Under the investigated conditions, the sintering rate for mechanically induced composite Cu/Cr particles was 2–4 times higher compared to the conventional Cu + Cr mixtures. The apparent sintering activation energy for the Cu/Cr powder was twice less than that for Cu–Cr mixture. It was concluded that the FSPS of nanostructured powders is an efficient approach for the fabrication of pseudo-alloys. Full article

(This article belongs to the Special Issue High Energy Ball Milling and Consolidation of Nanocomposite Powders)

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13 pages, 6165 KiB

Open AccessArticle

Characterization of Multiphase Oxide Layer Formation on Micro and Nanoscale Iron Particles

by Elena V. Zakharova, Ella L. Dzidziguri, Elena N. Sidorova, Andrey A. Vasiliev, Ivan A. Pelevin, Dmitriy Yu. Ozherelkov, Anton Yu. Nalivaiko and Alexander A. Gromov

Metals 2021, 11(1), 12; https://doi.org/10.3390/met11010012 - 23 Dec 2020

Cited by 5 | Viewed by 1521

Abstract

The article presents a detailed study and characterization of the oxide layers on the surface of iron particles of various sizes. Ten iron samples with a size range from a few nm to 50 µm were studied in detail using SEM, TEM, XRD, [...] Read more.

The article presents a detailed study and characterization of the oxide layers on the surface of iron particles of various sizes. Ten iron samples with a size range from a few nm to 50 µm were studied in detail using SEM, TEM, XRD, and TGA analysis. The composition of the multiphase oxide layers on the powder surface was investigated. The main components of the oxide layer were FeO, Fe₃O₄, and Fe₂O₃. By the obtained data, a model for the calculation of a multiphase oxide layer thickness on the surface of iron particles was proposed. The proposed model was validated and can be used for the characterization and certification of micro– and nanoscale iron particles. Full article

(This article belongs to the Special Issue High Energy Ball Milling and Consolidation of Nanocomposite Powders)

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11 pages, 3644 KiB

Open AccessArticle

High-Energy Ball Milling and Spark Plasma Sintering of the CoCrFeNiAl High-Entropy Alloy

by Alexander S. Rogachev, Nicholas A. Kochetov, Anna V. Panteleeva, Kirill V. Kuskov, Dmitry Yu. Kovalev, Alexander S. Shchukin, Sergey G. Vadchenko and Yury B. Scheck

Metals 2020, 10(11), 1489; https://doi.org/10.3390/met10111489 - 8 Nov 2020

Cited by 12 | Viewed by 2875

Abstract

Nanocrystalline powder of the CoCrFeNiAl high-entropy alloy was produced by high-energy ball milling (HEBM) and consolidated by spark plasma sintering (SPS). Microstructure and crystal structure transformations occurring in the course of HEBM and SPS processes were explored by Scanning Electron Microscopy (SEM), Energy [...] Read more.

Nanocrystalline powder of the CoCrFeNiAl high-entropy alloy was produced by high-energy ball milling (HEBM) and consolidated by spark plasma sintering (SPS). Microstructure and crystal structure transformations occurring in the course of HEBM and SPS processes were explored by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-Rays Diffraction (XRD) methods. Synthesized materials showed a microhardness of 4000–6000 MPa and electrical resistivity of 0.2 mΩ⋅cm at room temperature. Full article

(This article belongs to the Special Issue High Energy Ball Milling and Consolidation of Nanocomposite Powders)

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15 pages, 9512 KiB

Open AccessArticle

Refractory High-Entropy HfTaTiNbZr-Based Alloys by Combined Use of Ball Milling and Spark Plasma Sintering: Effect of Milling Intensity

by Natalia Shkodich, Alexey Sedegov, Kirill Kuskov, Sergey Busurin, Yury Scheck, Sergey Vadchenko and Dmitry Moskovskikh

Metals 2020, 10(9), 1268; https://doi.org/10.3390/met10091268 - 20 Sep 2020

Cited by 28 | Viewed by 3309

Abstract

For the first time, a powder of refractory body-centered cubic (bcc) HfTaTiNbZr-based high-entropy alloy (RHEA) was prepared by short-term (90 min) high-energy ball milling (HEBM) followed by spark plasma sintering (SPS) at 1300 °C for 10 min and the resultant bulk material was [...] Read more.

For the first time, a powder of refractory body-centered cubic (bcc) HfTaTiNbZr-based high-entropy alloy (RHEA) was prepared by short-term (90 min) high-energy ball milling (HEBM) followed by spark plasma sintering (SPS) at 1300 °C for 10 min and the resultant bulk material was characterized by XRD and SEM/EDX. The material showed ultra-high Vickers hardness (10.7 GPa) and a density of 9.87 ± 0.18 g/cm³ (98.7%). Our alloy was found to consist of HfZrTiTaNb-based solid solution with bcc structure as a main phase, a hexagonal closest packed (hcp) Hf/Zr-based solid solution, and Me₂Fe phases (Me = Hf, Zr) as minor admixtures. Principal elements of the HEA phase were uniformly distributed over the bulk of HfTaTiNbZr-based alloy. Similar alloys synthesized without milling or in the case of low-energy ball milling (LEBM, 10 h) consisted of a bcc HEA and a Hf/Zr-rich hcp solid solution; in this case, the Vickers hardness of such alloys was found to have a value of 6.4 GPa and 5.8 GPa, respectively. Full article

(This article belongs to the Special Issue High Energy Ball Milling and Consolidation of Nanocomposite Powders)

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