Special Issue "Mechanical Alloying"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (31 October 2016)

Special Issue Editor

Guest Editor
Dr. Chun-Liang Chen

Department of Materials Science and Engineering, National Dong Hwa University, Hualien 97401, Taiwan
Website | E-Mail
Interests: mechanical alloying; oxide dispersion strengthened (ODS) alloys; high temperature alloys; nuclear structural materials; irradiation damage; friction stir welding

Special Issue Information

Dear Colleagues,

The materials fabricated by mechanical alloying (MA) make a significant contribution to industrial applications. They represent a highly diverse and strongly multidisciplinary area, with links to numerous industrial sectors such as aerospace, energy, construction, automotive, transport, packaging, security and defense.

Mechanical alloying was selected as the most appropriate processing method to produce oxide dispersion strengthened (ODS) alloys that can be used at high temperature and radiation resistance applications. This special issue will include all aspects of theory, methods, materials and applications of mechanical alloying. Contributions in the following topics are encouraged.

  • Synthesis and processing in solid-state science and technology: high-energy milling, severe plastic deformation of materials (SPD), reaction milling.
  • New materials/processes: oxide dispersion strengthened (ODS) alloys, nanomaterial, nano-composites, and quasi-crystalline phases/materials.
  • Structural characterization: mechanically induced structural changes in materials (point defects, dislocations, clusters, precipitates, grain boundaries), surfaces and interfaces in activated solids.
  • New equipment and procedures: milling equipment based on improved milling dynamics, processing optimization and milling contamination.

Dr. Chun-Liang Chen
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 1000 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

  • mechanical alloying
  • oxide dispersion strengthened alloys
  • microstructure
  • nanomaterial
  • nano-composites

Published Papers (11 papers)

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Research

Open AccessArticle Formation and Corrosion Behavior of Mechanically-Alloyed Cu–Zr–Ti Bulk Metallic Glasses
Metals 2017, 7(4), 148; doi:10.3390/met7040148
Received: 31 August 2016 / Revised: 8 April 2017 / Accepted: 18 April 2017 / Published: 20 April 2017
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Abstract
Cu60Zr30Ti10 metallic glass powder was prepared by mechanically alloying a mixture of pure Cu, Zr, and Ti powders after 5 h of milling. Cu60Zr30Ti10 bulk metallic glass (BMG) was synthesized by vacuum hot
[...] Read more.
Cu60Zr30Ti10 metallic glass powder was prepared by mechanically alloying a mixture of pure Cu, Zr, and Ti powders after 5 h of milling. Cu60Zr30Ti10 bulk metallic glass (BMG) was synthesized by vacuum hot pressing the as-milled Cu60Zr30Ti10 metallic glass powder at 746 K in the pressure range of 0.72–1.20 GPa, and the structure was analyzed through X-ray diffraction and transmission electron microscopy. The pressure could enhance the thermal stability, and prolong the existence, of the amorphous phase inside the Cu60Zr30Ti10 powder. Furthermore, the corrosion behavior of the Cu-based BMG in four corrosive media was studied using a potentiodynamic method. The Cu60Zr30Ti10 BMG exhibited a low corrosion rate and current density in 1 N solutions of H2SO4, NaOH, and HNO3. X-ray photoelectron spectroscopy results revealed that the formation of Zr- and Ti-rich passive oxide layers provides a high corrosion resistance against 1 N H2SO4 and HNO3 solutions, and the breakdown of the protective film by Cl attack was responsible for pitting corrosion in a 3 wt % NaCl solution. The formation of oxide films and the nucleation and growth of pitting were analyzed through microstructural investigations. Full article
(This article belongs to the Special Issue Mechanical Alloying)
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Open AccessFeature PaperArticle A Study on the Aging Behavior of Al6061 Composites Reinforced with Y2O3 and TiC
Metals 2017, 7(1), 11; doi:10.3390/met7010011
Received: 12 October 2016 / Revised: 31 October 2016 / Accepted: 3 November 2016 / Published: 4 January 2017
Cited by 1 | PDF Full-text (7974 KB) | HTML Full-text | XML Full-text
Abstract
The reinforcement particles play important roles in determining microstructural development and properties of Al6061 composites. In the present work, the aging behavior of Al6061 reinforced with Y2O3 and TiC particles produced via mechanical alloying are investigated. The results indicate that
[...] Read more.
The reinforcement particles play important roles in determining microstructural development and properties of Al6061 composites. In the present work, the aging behavior of Al6061 reinforced with Y2O3 and TiC particles produced via mechanical alloying are investigated. The results indicate that the peak-aged Al6061 alloy without reinforcement demonstrates the highest hardness, which corresponds to the formation of the Mg–Si precipitates. However, precipitation formation is not observed in the case of the Al6061 composites, which can be attributed to the fact that the Mg–Si clusters and GP zones are inhibited by the presence of the reinforcement particles. The solute elements segregate in the complex oxides or carbides and contribute to only a slight increase in hardness. Full article
(This article belongs to the Special Issue Mechanical Alloying)
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Open AccessArticle Microstructures and Properties Evolution of Al-Cu-Mn Alloy with Addition of Vanadium
Metals 2017, 7(1), 10; doi:10.3390/met7010010
Received: 15 October 2016 / Revised: 22 December 2016 / Accepted: 23 December 2016 / Published: 30 December 2016
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Abstract
The effect of the vanadium addition on the microstructure, the precipitation behavior, and the mechanical properties of the Al-5.0Cu-0.4Mn alloy has been studied. The as-cast Al-5.0Cu-0.4Mn alloy was produced by squeeze casting and the heat treatment was carried out following the standard T6
[...] Read more.
The effect of the vanadium addition on the microstructure, the precipitation behavior, and the mechanical properties of the Al-5.0Cu-0.4Mn alloy has been studied. The as-cast Al-5.0Cu-0.4Mn alloy was produced by squeeze casting and the heat treatment was carried out following the standard T6 treatment. It is shown that, with the addition of V, grain refinement of aluminum occurred. During heat treatment, the addition of V accelerates the precipitation kinetics of θ′ (Al2Cu) phase along the grain boundaries, and promotes the growth rate of the θ′ in the α(Al) matrix. Meanwhile, the addition of V retards the precipitation of T (Al20Cu2Mn3) phase. The tensile strength of the Al-5.0Cu-0.4Mn alloy increases with the increase of V content, which can be explained by combined effects of the solid solution strengthening and precipitate strengthening. However, excessively high V addition deteriorates the mechanical properties by forming brittle coarse intermetallic phases. Full article
(This article belongs to the Special Issue Mechanical Alloying)
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Open AccessArticle Properties of Mechanically Alloyed W-Ti Materials with Dual Phase Particle Dispersion
Metals 2017, 7(1), 3; doi:10.3390/met7010003
Received: 31 October 2016 / Revised: 13 December 2016 / Accepted: 20 December 2016 / Published: 26 December 2016
Cited by 1 | PDF Full-text (3781 KB) | HTML Full-text | XML Full-text
Abstract
W alloys are currently widely studied materials for their potential application in future fusion reactors. In the presented study, we report on the preparation and properties of mechanically alloyed W-Ti powders compacted by pulsed electric current sintering. Four different powder compositions of W-(3%–7%)Ti
[...] Read more.
W alloys are currently widely studied materials for their potential application in future fusion reactors. In the presented study, we report on the preparation and properties of mechanically alloyed W-Ti powders compacted by pulsed electric current sintering. Four different powder compositions of W-(3%–7%)Ti with Hf or HfC were prepared. The alloys’ structure contains only high-melting-point phases, namely the W-Ti matrix, complex carbide (Ti,W,Hf)C and HfO2 particle dispersion; Ti in the form of a separate phase is not present. The bending strength of the alloys depends on the amount of Ti added. The addition of 3 wt. % Ti led to an increase whereas 7 wt. % Ti led to a major decrease in strength when compared to unalloyed tungsten sintered at similar conditions. The addition of Ti significantly lowered the room-temperature thermal conductivity of all prepared materials. However, unlike pure tungsten, the conductivity of the prepared alloys increased with the temperature. Thus, the thermal conductivity of the alloys at 1300 °C approached the value of the unalloyed tungsten. Full article
(This article belongs to the Special Issue Mechanical Alloying)
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Open AccessArticle Wear Behavior of Mechanically Alloyed Ti-Based Bulk Metallic Glass Composites Containing Carbon Nanotubes
Metals 2016, 6(11), 289; doi:10.3390/met6110289
Received: 23 August 2016 / Revised: 7 November 2016 / Accepted: 11 November 2016 / Published: 21 November 2016
Cited by 1 | PDF Full-text (3404 KB) | HTML Full-text | XML Full-text
Abstract
The present paper reports the preparation and wear behavior of mechanically alloyed Ti-based bulk metallic glass composites containing carbon nanotube (CNT) particles. The differential scanning calorimeter results show that the thermal stability of the amorphous matrix is affected by the presence of CNT
[...] Read more.
The present paper reports the preparation and wear behavior of mechanically alloyed Ti-based bulk metallic glass composites containing carbon nanotube (CNT) particles. The differential scanning calorimeter results show that the thermal stability of the amorphous matrix is affected by the presence of CNT particles. Changes in glass transition temperature (Tg) and crystallization temperature (Tx) suggest that deviations in the chemical composition of the amorphous matrix occurred because of a partial dissolution of the CNT species into the amorphous phase. Although the hardness of CNT/Ti50Cu28Ni15Sn7 bulk metallic glass composites is increased with the addition of CNT particles, the wear resistance of such composites is not directly proportional to their hardness, and does not follow the standard wear law. A worn surface under a high applied load shows that the 12 vol. % CNT/Ti50Cu28Ni15Sn7 bulk metallic glass composite suffers severe wear compared with monolithic Ti50Cu28Ni15Sn7 bulk metallic glass. Full article
(This article belongs to the Special Issue Mechanical Alloying)
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Open AccessFeature PaperArticle Similarities and Differences in Mechanical Alloying Processes of V-Si-B and Mo-Si-B Powders
Metals 2016, 6(10), 241; doi:10.3390/met6100241
Received: 31 August 2016 / Revised: 29 September 2016 / Accepted: 8 October 2016 / Published: 14 October 2016
Cited by 1 | PDF Full-text (3432 KB) | HTML Full-text | XML Full-text
Abstract
V-Si-B and Mo-Si-B alloys are currently the focus of materials research due to their excellent high temperature capabilities. To optimize the mechanical alloying (MA) process for these materials, we compare microstructures, morphology and particles size as well as hardness evolution during the milling
[...] Read more.
V-Si-B and Mo-Si-B alloys are currently the focus of materials research due to their excellent high temperature capabilities. To optimize the mechanical alloying (MA) process for these materials, we compare microstructures, morphology and particles size as well as hardness evolution during the milling process for the model alloys V-9Si-13B and Mo-9Si-8B. A variation of the rotational speed of the planetary ball mill and the type of grinding materials is therefore investigated. These modifications result in different impact energies during ball-powder-wall collisions, which are quantitatively described in this comparative study. Processing with tungsten carbide vials and balls provides slightly improved impact energies compared to vials and balls made of steel. However, contamination of the mechanically alloyed powders with flaked particles of tungsten carbide is unavoidable. In the case of using steel grinding materials, Fe contaminations are also detectable, which are solved in the V and Mo solid solution phases, respectively. Typical mechanisms that occur during the MA process such as fracturing and comminution are analyzed using the comminution rate KP. In both alloys, the welding processes are more pronounced compared to the fracturing processes. Full article
(This article belongs to the Special Issue Mechanical Alloying)
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Open AccessArticle Study on the Thermal Conductivity Characteristics of Graphene Prepared by the Planetary Ball Mill
Metals 2016, 6(10), 234; doi:10.3390/met6100234
Received: 16 August 2016 / Revised: 13 September 2016 / Accepted: 26 September 2016 / Published: 29 September 2016
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Abstract
This study was designed to examine the physical disintegration of graphene (GN), an excellent heat conductor, by using the planetary ball mill, a simple and convenient means to produce particles arbitrarily. The conditions for the disintegration of GN were distinguished by the rotation
[...] Read more.
This study was designed to examine the physical disintegration of graphene (GN), an excellent heat conductor, by using the planetary ball mill, a simple and convenient means to produce particles arbitrarily. The conditions for the disintegration of GN were distinguished by the rotation of the planetary ball mill (200 rpm, 400 rpm, and 600 rpm) and by the duration of its operation (30 min, 60 min, and 90 min), respectively. From the results, we saw that, when experimental conditions are 200 rpm with 60 min, the particle size was the smallest (at 328 nm) and the results of thermal conductivity were the highest. In the absorbance results, GN was well dispersed because the value of its absorbance is high. Full article
(This article belongs to the Special Issue Mechanical Alloying)
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Open AccessFeature PaperArticle Strong and Stable Nanocomposites Prepared by High-Pressure Torsion of Cu-Coated Fe Powders
Metals 2016, 6(10), 228; doi:10.3390/met6100228
Received: 30 August 2016 / Revised: 16 September 2016 / Accepted: 19 September 2016 / Published: 22 September 2016
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Abstract
Segregation and chemical inhomogeneity are well-known problems in powder metallurgy and are also an issue for new applications of powder mixtures, for example as starting materials for severe plastic deformation. In this study, Cu-coated Fe powder was prepared via immersion deposition, inductively hot-pressed
[...] Read more.
Segregation and chemical inhomogeneity are well-known problems in powder metallurgy and are also an issue for new applications of powder mixtures, for example as starting materials for severe plastic deformation. In this study, Cu-coated Fe powder was prepared via immersion deposition, inductively hot-pressed and subsequently deformed using high-pressure torsion. The homogeneity of the pressed material was found to be much better than that of powder mixtures that were prepared for comparison. During severe plastic deformation, higher hardness was observed for the coated powder as compared to powder mixtures even after low strains. In the saturation state, the coated powder was found to result in a hardness of about 600 HV, which is significantly harder than for the powder mixtures. This is attributed to the greater amount of impurities introduced by the coating process. It is shown that coated powders are promising starting materials for severe plastic deformation in order to reduce the amount of strain necessary to reach the saturation state and to obtain high strength and more homogeneous mechanical alloying. Full article
(This article belongs to the Special Issue Mechanical Alloying)
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Open AccessArticle Influence of Milling Atmosphere on the Controlled Formation of Ultrafine Dispersoids in Al-Based MMCs
Metals 2016, 6(9), 224; doi:10.3390/met6090224
Received: 27 July 2016 / Revised: 31 August 2016 / Accepted: 8 September 2016 / Published: 12 September 2016
Cited by 1 | PDF Full-text (4092 KB) | HTML Full-text | XML Full-text
Abstract
Properties of compacts made from aluminium powder, milled under different atmospheres, were evaluated. The duration of all the milling processes was 10 h, although different atmospheres were tested: vacuum, confined ammonia, and vacuum combined with a short-time ammonia gas flow (5 min). Milled
[...] Read more.
Properties of compacts made from aluminium powder, milled under different atmospheres, were evaluated. The duration of all the milling processes was 10 h, although different atmospheres were tested: vacuum, confined ammonia, and vacuum combined with a short-time ammonia gas flow (5 min). Milled powders were consolidated by cold uniaxial pressing and vacuum sintering. Full article
(This article belongs to the Special Issue Mechanical Alloying)
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Open AccessArticle Microstructure, Hardness Evolution, and Thermal Stability Mechanism of Mechanical Alloyed Cu-Nb Alloy during Heat Treatment
Metals 2016, 6(9), 194; doi:10.3390/met6090194
Received: 14 July 2016 / Revised: 11 August 2016 / Accepted: 12 August 2016 / Published: 26 August 2016
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Abstract
The microstructure, hardness evolution, and thermal stability of mechanically alloyed (MA-ed) nanocrystalline Cu–10 wt %Nb solid solution during heat treatment were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) observations, and microhardness measurement. It is
[...] Read more.
The microstructure, hardness evolution, and thermal stability of mechanically alloyed (MA-ed) nanocrystalline Cu–10 wt %Nb solid solution during heat treatment were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM) observations, and microhardness measurement. It is found that the pronounced precipitation of Nb from the Cu-Nb supersaturated solid solution occurs at temperatures up to 700 °C, and the annealed alloy shows a bi-nanostructure with Nb nanoparticles dispersed in the nanocrystalline Cu matrix. The bi-nanostructure remains stable with Cu crystalline grain size below 100 nm and Nb particle size around 10 nm even after annealing at 900 °C for 3 h. The microhardness of the annealed sample shows a small increase after annealing at 400 °C, and then it shows a slow decreasing trend with further increasing temperatures. With the help of the kinetics analyses, it is found that the coarsening of the stable Nb nanoparticles is controlled by volume diffusion. The enhanced stability of the nanocrystalline Cu microstructure is mainly attributed to the solute drag and precipitate pinning effects. Full article
(This article belongs to the Special Issue Mechanical Alloying)
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Open AccessCommunication Mechanical Alloying Synthesis of Co9S8 Particles as Materials for Supercapacitors
Metals 2016, 6(6), 142; doi:10.3390/met6060142
Received: 6 May 2016 / Revised: 28 May 2016 / Accepted: 31 May 2016 / Published: 16 June 2016
Cited by 7 | PDF Full-text (1330 KB) | HTML Full-text | XML Full-text
Abstract
Cobalt sulfide (Co9S8) particles are compounded as the electrode materials of supercapacitors by a mechanical alloying method. They show excellent properties including good cycling stability and high specific capacitance. A supercapacitor is assembled using Co9S8 as
[...] Read more.
Cobalt sulfide (Co9S8) particles are compounded as the electrode materials of supercapacitors by a mechanical alloying method. They show excellent properties including good cycling stability and high specific capacitance. A supercapacitor is assembled using Co9S8 as the anode and activated carbon (AC) as the cathode. It gains a maximum specific capacitance of 55 F·g−1 at a current density of 0.5 A·g−1, and also an energy density of 15 Wh·kg−1. Those results show that the novel and facile synthetic route may be able to offer a new way to synthesize alloy compounds with excellent supercapacitive properties. Full article
(This article belongs to the Special Issue Mechanical Alloying)
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Planned Papers

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

Title: Structural evolution of copper coated iron powder during severe plastic deformation
Author: Timo Müller, Andrea Bachmaier, Reinhard Pippan
Affiliation: Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Leoben, Austria
Abstract: Severe plastic deformation of binary immiscible alloys can result in either nanostructured composites or supersaturated solutions depending on the chemical composition of the material and the amount of strain. During deformation, refinement of the microstructure takes place until a state of saturation is obtained. The kinetics of the refinement process can be adjusted by various parameters. One of these is the initial structure of the material. In this study, iron powder was coated with copper via immersion deposition. Subsequently, the coated powder was deformed using high pressure torsion. The coating of the powder does not allow any agglomeration of one element over larger regions, as it might occur in powder mixtures. Therefore, an acceleration of the structural refinement process was expected as compared to the deformation of powder mixtures. X-ray diffraction as well as scanning electron microscopy including electron backscatter diffraction was used to analyze the structure after different amounts of deformation, which was then related to the microhardness of the material. Equivalent experiments using mixtures of iron and copper powders were performed to compare the results and discuss both the avoidance of agglomeration and the enhanced presence of impurities in the coated powder.

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