Advances in Powder Metallurgy

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

Deadline for manuscript submissions: closed (31 August 2021) | Viewed by 29864

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Guest Editor
Faculty of Mechanical Engineering and Management, Institute of Materials Science and Engineering, Poznan University of Technology, 60-965 Poznan, Poland
Interests: mechanochemical material synthesis; innovative approach in powder sintering; nano objects synthesis and sintering; metal-based nanocomposites; surface functionalization
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Special Issue Information

Dear Colleagues,

The increasing market share of sintered materials that at the same time reduce the use of traditional manufacturing technologies remains a clearly noticeable trend and evident source of development of new materials and technologies. Advances in Powder Metallurgy, which include control and characterization of the material in all processing steps with its final properties analysis, are the scope for this Special Issue. From the beginning, powder metallurgy methods have been used for the manufacturing of materials where other technologies of properties shaping cannot be applied. The advantages of the method quickly brought new consumers, expanding its potential application to the group of the metals, their alloys, and composite structures. The high purity of powders controlled at the stage of their production, together with the possibility of affecting their size and morphology that determines the end properties of products, have made powder metallurgy in new material markets highly attractive. For the abovementioned reasons, the process of the sinters production by itself is not meaningless, instead staying significant for the final obtained material structure. The process, realized either in stages or all at once and based on force value control and temperature field operation as well as other factors that include an influence of innovative current flow, microwave radiation or lasers in incremental technologies assisted processes, allows obtaining fully compacted materials without requiring an additional post-processing operation.

In this Special Issue, we welcome articles that focus on material preparation methods and their influence on the final products’ performance both from the powder stage and/or compaction stadium. Fully controllable fast and low-cost processes especially remain of interest, with a high implementation potential in advanced powder metallurgy that allows producing high-performance products.

Dr. Andrzej Miklaszewski
Guest Editor

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Keywords

  • powder metallurgy
  • mechanical alloying
  • hot pressing
  • isostatic sintering
  • field-assisted sintering
  • microwave-assisted sintering
  • laser-assisted sintering
  • structural characterization

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Published Papers (12 papers)

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Research

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14 pages, 5096 KiB  
Article
Optimization of the Microwave-Assisted Carbothermical Reduction Process for Metals from Electric Arc Furnace Dust with Biochar
by Anton Anzulevich, Leonid Butko, Dmitrii Kalganov, Dmitrii Pavlov, Valentin Tolkachev, Alexander Fedii, Vasiliy Buchelnikov and Zhiwei Peng
Metals 2021, 11(11), 1765; https://doi.org/10.3390/met11111765 - 3 Nov 2021
Cited by 3 | Viewed by 1663
Abstract
The main purpose of this work was to extract valuable metals from EAF dust with the addition of biochar, using microwaves to control and optimize the carbothermical reduction process. To achieve better microwave penetration and the most homogeneous electromagnetic heat source distribution possible [...] Read more.
The main purpose of this work was to extract valuable metals from EAF dust with the addition of biochar, using microwaves to control and optimize the carbothermical reduction process. To achieve better microwave penetration and the most homogeneous electromagnetic heat source distribution possible in a sample, the content of EAF dust and biochar in centimeter-size spherical particles prepared by the pelletization process was considered to be radially heterogeneous. The content of EAF dust was determined experimentally and the effective permittivity, permeability, and thermal conductivity of the EAF dust as well as biochar–EAF powder mixture were determined using effective medium approximation. The microwave heating of a multilayered pellet of biochar-containing EAF dust was simulated and investigated. The influence of the distribution of the components within the pellet on the effectiveness of the microwave heating was investigated, as was the influence of the biochar conductivity. The interaction of the pellet with both plane waves in free space and with H10 mode waves in a single-mode waveguide was considered. The most optimal distribution of EAF dust and biochar within the pellet for the reduction process was determined. Full article
(This article belongs to the Special Issue Advances in Powder Metallurgy)
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11 pages, 50522 KiB  
Article
Manufacturing of Tool Steels by PBF-EB
by Alexander Kirchner, Burghardt Klöden, Marie Franke-Jurisch, Luis Inarra Rauh-Hain and Thomas Weißgärber
Metals 2021, 11(10), 1640; https://doi.org/10.3390/met11101640 - 14 Oct 2021
Cited by 4 | Viewed by 2685
Abstract
Additive manufacturing (AM) of metals is stimulating the tool making industry. Moreover, besides the production of lost forms, AM processes are now being used to directly generate tools, molds or parts, leading to massive time savings. In the case of material development for [...] Read more.
Additive manufacturing (AM) of metals is stimulating the tool making industry. Moreover, besides the production of lost forms, AM processes are now being used to directly generate tools, molds or parts, leading to massive time savings. In the case of material development for AM, the challenge is to operate with carbon-containing iron-based materials distinguished by high strength and hardness, as well as high corrosion resistance and thermal conductivity. Often, those materials are susceptible to crack formation during processing. Using Electron Beam Powder Bed Fusion (PBF-EB), the challenge of crack formation can be overcome by using high process temperatures in the range 800–900 °C. In this paper, results on the processing of a cold-working tool steel (X65MoCrWV3-2) and a hot-working steel (X37CrMoV5-1) will be presented. These include the processing window, processing strategies to minimize the density of cracks and properties with respect to microstructure and hardness. Full article
(This article belongs to the Special Issue Advances in Powder Metallurgy)
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14 pages, 3451 KiB  
Article
Structure Evolution of Ni36Al27Co37 Alloy in the Process of Mechanical Alloying and Plasma Spheroidization
by Alina K. Mazeeva, Artem Kim, Nikolay E. Ozerskoi, Aleksey I. Shamshurin, Nikolay G. Razumov, Denis V. Nazarov and Anatoliy A. Popovich
Metals 2021, 11(10), 1557; https://doi.org/10.3390/met11101557 - 29 Sep 2021
Cited by 2 | Viewed by 1631
Abstract
In this paper, a novel approach to obtain a ferromagnetic material for smart applications was implied. A combination of mechanical alloying (MA) and plasma spheroidization (PS) was applied to produce Ni36Al27Co37 spherical powder. Then its structure was systematically [...] Read more.
In this paper, a novel approach to obtain a ferromagnetic material for smart applications was implied. A combination of mechanical alloying (MA) and plasma spheroidization (PS) was applied to produce Ni36Al27Co37 spherical powder. Then its structure was systematically studied. It was shown that homogenization of the structure occurs due to mechanism of layered structure formation. The dependence of the lamella thickness on the energy dose input at MA was defined. It was found that 14.7 W⋅h/g is sufficient to obtain lamella thickness of 1 μm and less. The low-energy mode of a planetary mill with rotation speeds of the main disk/bowl of 150/−300 rpm makes it possible to achieve a uniform element distribution upon a minimal amount of impurity. During MA in an attritor Ni3Al-type intermetallic compounds are formed that result in more intensive degradation in particle size. Plasma spheroidization of the powder after MA allowed obtaining Ni36Al27Co37 spherical powder. The powder had a fine β + γ-structure. The particle size distribution remains almost unchanged compared to the MA stage. Coercivity of the powder is 79 Oe. The powder obtained meets the requirements of selective laser melting technology, but also can be utilized as a functional filler in various magnetic composites. Full article
(This article belongs to the Special Issue Advances in Powder Metallurgy)
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13 pages, 5115 KiB  
Article
Effect of Bimodal Grain Structure on the Microstructural and Mechanical Evolution of Al-Mg/CNTs Composite
by Behzad Sadeghi and Pasquale Cavaliere
Metals 2021, 11(10), 1524; https://doi.org/10.3390/met11101524 - 26 Sep 2021
Cited by 9 | Viewed by 2017
Abstract
The Al-Mg alloy structure reinforced with carbon nanotubes was evaluated after the composites production through a modified flake metallurgy technique followed by hot extrusion. The obtained bimodal microstructure of the matrix allowed to identify the microstructural mechanisms leading to high strength; uniform elongation [...] Read more.
The Al-Mg alloy structure reinforced with carbon nanotubes was evaluated after the composites production through a modified flake metallurgy technique followed by hot extrusion. The obtained bimodal microstructure of the matrix allowed to identify the microstructural mechanisms leading to high strength; uniform elongation and strain hardening ability of the produced composites. The presence of Mg transformed the native Al2O3 layer into spinel MgAl2O4 nano-phases dispersed both inside CG and UFGs and on the interfaces, improving the interfacial bonding of Al-Al as well as Al-CNT. The effect of the reinforcing phases percentages on the dislocations mechanisms evolution was evaluated through stress relaxation tests leading to the underlying of the effect of reinforcing phases on the modification of the interphase influence zone Full article
(This article belongs to the Special Issue Advances in Powder Metallurgy)
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17 pages, 3425 KiB  
Article
Effect of CoCrMo Addition on Ti6Al4V/xCoCrMo Biomedical Composites Processed by Powder Metallurgy
by Elena Mihalcea, Luis Olmos, Héctor Vergara-Hernández, Omar Jimenez, Jorge Chávez and Dante Arteaga
Metals 2021, 11(10), 1523; https://doi.org/10.3390/met11101523 - 26 Sep 2021
Cited by 2 | Viewed by 1472
Abstract
A detailed experimental and numerical investigation was performed on a Ti6Al4V/xCoCrMo biomedical composite for bone implant applications. The aim was to understand the effect generated by the addition of different volume fractions of CoCrMo particles on a Ti6Al4V matrix composite processed by powder [...] Read more.
A detailed experimental and numerical investigation was performed on a Ti6Al4V/xCoCrMo biomedical composite for bone implant applications. The aim was to understand the effect generated by the addition of different volume fractions of CoCrMo particles on a Ti6Al4V matrix composite processed by powder metallurgy. Distribution of CoCrMo particles inside a matrix was observed by computed microtomography. Three-dimensional image analysis allowed for the deduction that the mechanism that permitted percolation within the powder mixture was the cluster formation at 30 vol.% of CoCrMo and at a coordination number of Co–Co contacts of 2.8, which confirms existing models. Densification during powder compaction was driven by larger indentations at the Ti–Co contacts for lower quantities of CoCrMo than for those reaching percolation. Sintering was studied by dilatometry tests at 1130 °C, and results indicated that solid-state sintering generated the formation of a rigid skeleton. This endured the stress generated by the eutectic reaction liquid, which filled the interparticle porosity, resulting in relative densities above 90%. Microstructure was analyzed by SEM and X-ray diffraction, and results showed a Ti6Al4V matrix surrounded by a Ti2Co eutectic phase. In addition, the hardness of composites increased up to three times compared to the Ti6Al4V alloy. It was concluded that the best properties were obtained from 20 vol.% of CoCrMo. Full article
(This article belongs to the Special Issue Advances in Powder Metallurgy)
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7 pages, 2487 KiB  
Article
Evaluation of Harmonic Structure Obtained in Mechanically Milled Powders and Pulse Plasma Sintered Compacts of Austenitic Steel
by Dariusz Oleszak, Aleksandra Sadurska and Grzegorz Cieślak
Metals 2021, 11(3), 386; https://doi.org/10.3390/met11030386 - 26 Feb 2021
Cited by 1 | Viewed by 1313
Abstract
The paper describes an attempt to obtain harmonic structure (HS) in AISI308L steel. Harmonic structure is the term related to the microstructure fabricated by mechanical milling of metallic powders under soft milling conditions, resulting in the formation of plastically deformed, grain-refined shell and [...] Read more.
The paper describes an attempt to obtain harmonic structure (HS) in AISI308L steel. Harmonic structure is the term related to the microstructure fabricated by mechanical milling of metallic powders under soft milling conditions, resulting in the formation of plastically deformed, grain-refined shell and unchanged core. This microstructure can be preserved after successful powder compaction. The powders of AISI308L steel were milled under soft condition up to 50 h and then compacted by pulse plasma sintering at 900–1100 °C. For powders and compacts XRD, SEM and hardness measurements were applied as characterization techniques. The milling process resulted in austenite transformation into nanocrystalline ferrite and formation of grain refined outer layer. The applied pulse plasma sintering parameters allowed preservation of this microstructure and manufacturing of compacts with homogeneous distribution of elements, relative density above 95% and hardness in the range 167–185 HV, depending on sintering temperature. Simultaneously, the starting phase composition was restored, i.e., austenite with 12% contribution of ferrite. The crystallite size of austenite was about 20 nm and was significantly smaller then in starting powders. Full article
(This article belongs to the Special Issue Advances in Powder Metallurgy)
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12 pages, 6068 KiB  
Article
Accelerated Spheroidization of Cementite in Sintered Ultrahigh Carbon Steel by Warm Deformation
by Piotr Nikiel, Stefan Szczepanik and Grzegorz Korpała
Metals 2021, 11(2), 328; https://doi.org/10.3390/met11020328 - 13 Feb 2021
Cited by 4 | Viewed by 2545
Abstract
Evolution of microstructure and hardness in quenched ultrahigh carbon steel Fe-0.85Mo-0.6Si-1.4C by warm compression on a Bähr plastometer-dilatometer at 775 °C and at 0.001 to 1 s−1 strain rate range is reported. The material was prepared via powder metallurgy: cold pressing and [...] Read more.
Evolution of microstructure and hardness in quenched ultrahigh carbon steel Fe-0.85Mo-0.6Si-1.4C by warm compression on a Bähr plastometer-dilatometer at 775 °C and at 0.001 to 1 s−1 strain rate range is reported. The material was prepared via powder metallurgy: cold pressing and liquid phase sintering. Independent of strain rate, the initial martenstic microstructure was transformed to ferrite and spheroidized cementite. Strain rate had an effect on size and shape of spheroidized Fe3C precipitates: the higher the strain rate, the smaller the precipitates. Morphology of the spheroidized carbides influenced hardness, with the highest hardness, 362 HV10, for strain rate 1 s−1 and the lowest, 295 HV10, for the lowest strain rate 0.001 s−1. Resultant microstructure and ambient temperature mechanical properties were comparable to those of the material that had undergone a fully spheroidizing treatment with increased time and energy consumption, indicating that it can be dispensed with in industrial processing. All our results are consistent with the Hall–Petch relation developed for spheroidized steels. Full article
(This article belongs to the Special Issue Advances in Powder Metallurgy)
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17 pages, 10053 KiB  
Article
The Ultrafine-Grain Yttria-Stabilized Zirconia Reinforced β-Titanium Matrix Composites
by Daria Piechowiak, Andrzej Miklaszewski and Natalia Makuch-Dziarska
Metals 2021, 11(2), 240; https://doi.org/10.3390/met11020240 - 1 Feb 2021
Cited by 2 | Viewed by 2141
Abstract
Ti(β) alloys have become an important class in the biomedical field due to low Young’s modulus, excellent physical properties, and biocompatibility. However, their properties, like biocompatibility and, also, low wear resistance, can be still enhanced. To improve those properties, a composites approach can [...] Read more.
Ti(β) alloys have become an important class in the biomedical field due to low Young’s modulus, excellent physical properties, and biocompatibility. However, their properties, like biocompatibility and, also, low wear resistance, can be still enhanced. To improve those properties, a composites approach can be applied. This research shows a new approach of the composite structure fabrication by powder metallurgy methods which for a stabile yttria-stabilized zirconia (YSZ) reinforcement phase could be obtained in the ultra-fine grain range beta-titanium matrix. In this work, the composites based on ultrafine-grain Ti-xMo (x = 23 wt%, 27 wt%, 35 wt%) alloys with addition 3 wt%, 5 wt% or 10 wt% YSZ, and 1 wt% Y2O3 were fabricated by the mechanical alloying and hot-pressing approach. Obtained composites were characterized in terms of their phase composition, microstructure, Young’s modulus, hardness, surface free energy (SFE), and corrosion resistance. The structure of composites consists of phases based on Ti–Mo, Ti(α), and YSZ. The oxide (YSZ) powder tends to agglomerate during processing, which is revealed in composites based on Ti23Mo and Ti27Mo. However, composites based on Ti35Mo are characterized by a high degree of dispersibility and this influences significantly the hardness value of the composites obtained. Only in the case of composites based on Ti35Mo, the decrease in Young’ Modulus is observed. All composites possess a hydrophilic surface property and good corrosion resistance. Full article
(This article belongs to the Special Issue Advances in Powder Metallurgy)
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15 pages, 5194 KiB  
Article
Central Composite Experiment Design (CCD)-Response Surface Method (RSM) to Optimize the Sintering Process of Ti-6Al-4V Alloy
by Jing Xia, Shaopeng Liu, Bing Zhang and Yungui Chen
Metals 2021, 11(2), 197; https://doi.org/10.3390/met11020197 - 22 Jan 2021
Cited by 3 | Viewed by 2515
Abstract
It is widely acknowledged that the blended elemental (BE) powder metallurgy (PM) Ti6Al4V alloy attracted unusual due to its low cost and comprehensive mechanical properties. However, the high porosity and mediocre mechanical properties of traditional vacuum sintering limited its application. To achieve better [...] Read more.
It is widely acknowledged that the blended elemental (BE) powder metallurgy (PM) Ti6Al4V alloy attracted unusual due to its low cost and comprehensive mechanical properties. However, the high porosity and mediocre mechanical properties of traditional vacuum sintering limited its application. To achieve better mechanical performance, the central composite designs (CCDs) method was employed to analyze the influence of sintering parameters, such as sintering temperature (St), heating rate (Hr), and holding time (Ht). The results indicated that St makes the most significant contribution to compressive strength and sintering density, accounting for 95.5% and 86.54% respectively. In addition, Ht makes the most significant contribution to compression ratio, which accounted for 89.35%. Through the analysis of response surface methodology (RSM), the optimum sintering parameters (St, Ht, Hr) could be considered to be 1300 °C, 148 min and 5 °C/min. In addition, verification experiments were carried out under the optimum conditions, and the experimental results were in good agreement with the predicted values, since the deviation of the predicted and experimental values was less than 4.9%. Therefore, the results of this study could certify the reliability of CCDs method, which would contribute to the development of titanium alloys with low cost and high mechanical properties. Full article
(This article belongs to the Special Issue Advances in Powder Metallurgy)
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14 pages, 3267 KiB  
Article
Effect of Sample Preparation Pressure on Transformation Law of Low-Valent Titanium Oxide in a Multi-Stage Reduction Process
by Shigang Fan, Zhihe Dou, Ting’an Zhang, Ji-sen Yan and Li-ping Niu
Metals 2020, 10(9), 1259; https://doi.org/10.3390/met10091259 - 18 Sep 2020
Cited by 1 | Viewed by 2043
Abstract
A novel method for preparing titanium powder by multi-stage reduction of TiO2 was proposed. Its core is the preparation of high-quality low-valent titanium oxide. In this paper, the effect mechanism of different sample preparation pressures on the preparation of low-valent titanium oxide [...] Read more.
A novel method for preparing titanium powder by multi-stage reduction of TiO2 was proposed. Its core is the preparation of high-quality low-valent titanium oxide. In this paper, the effect mechanism of different sample preparation pressures on the preparation of low-valent titanium oxide by the primary reduction (self-propagating high-temperature synthesis mode, SHS) of the Mg-TiO2 system was studied. The results show that the generation of Mg thermal fluid is the key link of the self-sustaining chemical reaction of the Mg-TiO2 system. Titanium exists inα-Ti and TiO at the end of combustion, and constitutes a non-stoichiometric low-valent titanium oxide. The sample preparation pressure determines the proportion of pores reserved for Mg diffusion in the compacts and the contact area of the reactants, thereby determining the partitioning behavior and heat transfer effect of Mg thermal fluid during the combustion process. When the sample preparation pressure is 75 MPa (relative density is 0.66 ± 0.01), the combustion effect is optimal, and the low-valent titanium oxide with oxygen content of 15.1% can be obtained. It was subjected to deep reduction to obtain a titanium powder product with an oxygen content of 0.27%. Full article
(This article belongs to the Special Issue Advances in Powder Metallurgy)
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12 pages, 7428 KiB  
Article
Effects of Powder Preparation and Sintering Temperature on Properties of Spark Plasma Sintered Ti-48Al-2Cr-8Nb Alloy
by Zhenhua Wang, Haoxuan Sun, Yulei Du and Juntang Yuan
Metals 2019, 9(8), 861; https://doi.org/10.3390/met9080861 - 7 Aug 2019
Cited by 11 | Viewed by 3440
Abstract
TiAl alloy has become a key element in aerospace and automotive engine development due to its favorable high temperature mechanical properties and low density. In this paper, high performance TiAl alloy was prepared using atomized Ti-48Al-2Cr-8Nb powder by spark plasma sintering. This paper [...] Read more.
TiAl alloy has become a key element in aerospace and automotive engine development due to its favorable high temperature mechanical properties and low density. In this paper, high performance TiAl alloy was prepared using atomized Ti-48Al-2Cr-8Nb powder by spark plasma sintering. This paper analyzed the variation of density, microstructure, Vickers hardness, and fracture strength of TiAl alloys prepared with spherical pre-alloyed powder (named as SP powder) and pre-alloyed powder after 12 h of ball milling (named as MP powder) at different sintering temperatures. The results indicate that the density, Vickers hardness, and room temperature (25 °C) bending strength of Ti-48Al-2Cr-8Nb alloy sintered using MP powder, are significantly higher than that of TiAl alloy sintered using SP powder. Specifically, the densification temperature of the MP powder sintered specimen is reduced by 100 °C, the Vickers hardness is increased by 15%, and the room temperature bending strength is increased by 51.9% at a sintering temperature of 1250 °C. The microstructure analysis shows that the Ti-48Al-2Cr-8Nb alloy has the best bending strength when it has a fine grain phase structure. Full article
(This article belongs to the Special Issue Advances in Powder Metallurgy)
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Review

Jump to: Research

14 pages, 2748 KiB  
Review
Research Progress of Nano Copper Lubricant Additives on Engineering Tribology
by Junde Guo, Yingxiang Zhao, Biao Sun, Puchao Wang, Zhijie Wang and Hao Dong
Metals 2021, 11(12), 2006; https://doi.org/10.3390/met11122006 - 12 Dec 2021
Cited by 10 | Viewed by 3790
Abstract
Nanoparticles have as characteristics super sliding, extreme pressure, self-healing, etc., which can improve the friction reduction and anti-wear performance of sliding components, when used as lubricating oil additives. Nano-copper particles have a good synergistic effect with other antifriction agents, anti-wear agents, antioxidants and [...] Read more.
Nanoparticles have as characteristics super sliding, extreme pressure, self-healing, etc., which can improve the friction reduction and anti-wear performance of sliding components, when used as lubricating oil additives. Nano-copper particles have a good synergistic effect with other antifriction agents, anti-wear agents, antioxidants and grease additives because of their low shear strength and grain boundary slip effect, showing a better anti-friction and anti-wear effect. However, nanoparticles are prone to conglomerate, and this causes a bottleneck in the application of dispersant for nano-copper in a lubricating oil system. The regulation of nanosized effect and surface properties has great engineering significance in compensating for the precision in manufacturing accuracy. This paper comprehensively reviews the tribological research progress of nano-copper as a lubricant additive, which provides a reference to the application of nano-copper particles as lubricating oil additives on engineering tribology. Full article
(This article belongs to the Special Issue Advances in Powder Metallurgy)
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