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3 pages, 165 KiB

Open AccessEditorial

Mechanical Alloying: Processing and Materials

by Joan-Josep Suñol

Metals 2021, 11(5), 798; https://doi.org/10.3390/met11050798 - 14 May 2021

Cited by 8 | Viewed by 1741

Abstract

Mechanical alloying is a technique involving the production of alloys and compounds, which permits the development of metastable materials (with amorphous or nanocrystalline microstructure) or the obtention of solid solutions with extended solubility [...] Full article

(This article belongs to the Special Issue Mechanical Alloying: Processing and Materials)

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14 pages, 3045 KiB

Open AccessFeature PaperArticle

Fe-X-B-Cu (X = Nb, NiZr) Alloys Produced by Mechanical Alloying: Influence of Milling Device

by Albert Carrillo, Joan Saurina, Lluisa Escoda and Joan-Josep Suñol

Metals 2021, 11(3), 379; https://doi.org/10.3390/met11030379 - 25 Feb 2021

Cited by 4 | Viewed by 1506

Abstract

In this work, we analyze the influence of the milling device in the microstructural evolution of two Fe-X-B-Cu (X = Nb, NiZr) alloys produced by mechanical alloying (MA). The two milling devices are a planetary mil (P7) and a shaker mill (SPEX 8000). [...] Read more.

In this work, we analyze the influence of the milling device in the microstructural evolution of two Fe-X-B-Cu (X = Nb, NiZr) alloys produced by mechanical alloying (MA). The two milling devices are a planetary mil (P7) and a shaker mill (SPEX 8000). Microstructural analysis by X-ray diffraction detects the formation of a Fe rich solid solution. In the Fe-Nb-B-Cu alloy produced in the shaker mill also appears a Nb(B) minor phase, whereas in the Fe-NiZr-B-Cu alloy produced in the planetary mill, a minor disordered phase is formed. The comparative study regarding the energy transferred per unit of time in both devices determines that the shaker mill is more energetic. This fact explains that in the Fe-Nb-B-Cu alloy, Nb has not been introduced in the main Fe rich phase, whereas in the Fe-NiZr-B-Cu alloy milled in the shaker mill was formed the highly disordered phase. With regard to thermal analysis, the values of the apparent activation energies of the main crystallization process (above 200 kJ/mol) correspond to the crystalline growth of the nanocrystalline Fe rich phase. Full article

(This article belongs to the Special Issue Mechanical Alloying: Processing and Materials)

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16 pages, 2986 KiB

Open AccessArticle

Structure-Phase Transformations in the Course of Solid-State Mechanical Alloying of High-Nitrogen Chromium-Manganese Steels

by Kirill Lyashkov, Valery Shabashov, Andrey Zamatovskii, Kirill Kozlov, Natalya Kataeva, Evgenii Novikov and Yurii Ustyugov

Metals 2021, 11(2), 301; https://doi.org/10.3390/met11020301 - 09 Feb 2021

Cited by 5 | Viewed by 1960

Abstract

The solid-state mechanical alloying (MA) of high-nitrogen chromium-manganese austenite steel—MA in a planetary ball mill, —was studied by methods of Mössbauer spectroscopy and transmission electron microscopy (TEM). In the capacity of a material for the alloying we used mixtures of the binary Fe–Mn [...] Read more.

The solid-state mechanical alloying (MA) of high-nitrogen chromium-manganese austenite steel—MA in a planetary ball mill, —was studied by methods of Mössbauer spectroscopy and transmission electron microscopy (TEM). In the capacity of a material for the alloying we used mixtures of the binary Fe–Mn and Fe–Cr alloys with the nitrides CrN (Cr₂N) and Mn₂N. It is shown that ball milling of the mixtures has led to the occurrence of the α → γ transitions being accompanied by the (i) formation of the solid solutions supersaturated with nitrogen and by (ii) their decomposition with the formation of secondary nitrides. The austenite formed by the ball milling and subsequent annealing at 700–800 °C, was a submicrocrystalline one that contained secondary nano-sized crystalline CrN (Cr₂N) nitrides. It has been established that using the nitride Mn₂N as nitrogen-containing addition is more preferable for the formation and stabilization of austenite—in the course of the MA and subsequent annealing—because of the formation of the concentration-inhomogeneous regions of γ phase enriched with austenite-forming low-mobile manganese. Full article

(This article belongs to the Special Issue Mechanical Alloying: Processing and Materials)

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16 pages, 3023 KiB

Open AccessArticle

Effects of the Addition of Fe, Co on the Azo Dye Degradation Ability of Mn-Al Mechanically Alloyed Powders

by Wael Ben Mbarek, Joan Saurina, Lluisa Escoda, Eloi Pineda, Mohamed Khitouni and Joan-Josep Suñol

Metals 2020, 10(12), 1578; https://doi.org/10.3390/met10121578 - 25 Nov 2020

Cited by 6 | Viewed by 2071

Abstract

Azo compounds are used in the textile and leather industry. A significant step during the azo dyes treatment of water is the degradation by breaking the N=N bonds. This break produces the decolorization of water. In this research work, 10% atomic of Fe [...] Read more.

Azo compounds are used in the textile and leather industry. A significant step during the azo dyes treatment of water is the degradation by breaking the N=N bonds. This break produces the decolorization of water. In this research work, 10% atomic of Fe or Co was added to produce ternary Mn-Al-rich, nanostructured, mechanically alloyed powders in order to improve the decolorization of Reactive Black 5 solutions and to check Fe and Co addition’s influence. The microstructure was followed by X-ray diffraction, the morphology and composition by electronic microscopy and energy-dispersive X-ray spectroscopy (EDS) microanalysis. The dye degradation was monitored with ultraviolet/visible absorption spectrophotometry. After degradation, the remaining organic compound was checked by high-performance liquid chromatography (HPLC) and the functional groups of the powdered alloys by infrared spectroscopy. Fe addition to Mn-Al displayed faster kinetics and a higher efficiency than the Co addition. The Mn-Al-Fe solution (0.25 g/100 mL) was fully decolorized in 5 min. On the other side, Mn-Al-Co powders were able to successfully decolorize the dyed solution in 10 min under the same conditions. Thus, nanocrystalline Fe-doped Mn-Al alloys are good candidates for use in the decolorization process, in comparison with Co-doped and other intermetallic particles. Full article

(This article belongs to the Special Issue Mechanical Alloying: Processing and Materials)

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13 pages, 7684 KiB

Open AccessArticle

A Novel Non-Equiatomic (W₃₅Ta₃₅Mo₁₅Nb₁₅)₉₅Ni₅ Refractory High Entropy Alloy with High Density Fabricated by Powder Metallurgical Process

by Bohua Duan, Yingrui Yu, Xinli Liu, Dezhi Wang and Zhuangzhi Wu

Metals 2020, 10(11), 1436; https://doi.org/10.3390/met10111436 - 29 Oct 2020

Cited by 7 | Viewed by 2235

Abstract

A non-equiatomic refractory high entropy alloy (RHEA), (W₃₅Ta₃₅Mo₁₅Nb₁₅)₉₅Ni₅ with high density of 14.55 g/cm³ was fabricated by powder metallurgical process of mechanical alloying (MA) and spark plasma sintering (SPS). The mechanical [...] Read more.

A non-equiatomic refractory high entropy alloy (RHEA), (W₃₅Ta₃₅Mo₁₅Nb₁₅)₉₅Ni₅ with high density of 14.55 g/cm³ was fabricated by powder metallurgical process of mechanical alloying (MA) and spark plasma sintering (SPS). The mechanical alloying behavior of the metallic powders was studied systematically, and the microstructure and phase composition for both the powders and alloys were analyzed. Results show that the crystal consists of the primary solid solution and marginal oxide inclusion (Nb_5.7Ni₄Ta_2.3O₂). In addition, the maximum strength, yield strength and fracture strain are, 2562 MPa, 2128 MPa, 8.16%, respectively. Full article

(This article belongs to the Special Issue Mechanical Alloying: Processing and Materials)

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9 pages, 2845 KiB

Open AccessArticle

Mechanical Amorphization and Recrystallization of Mn-Co(Fe)-Ge(Si) Compositions

by Antonio Vidal-Crespo, Jhon J. Ipus, Javier S. Blázquez and Alejandro Conde

Metals 2019, 9(5), 534; https://doi.org/10.3390/met9050534 - 08 May 2019

Cited by 5 | Viewed by 2536

Abstract

Mechanical alloying using a planetary ball mill allowed us to obtain two homogeneous systems formed by units with nanometer size and MnCo_0.8Fe_0.2Ge_1−xSi_x stoichiometry (x = 0 and 0.5). The phase evolution of the systems [...] Read more.

Mechanical alloying using a planetary ball mill allowed us to obtain two homogeneous systems formed by units with nanometer size and MnCo_0.8Fe_0.2Ge_1−xSi_x stoichiometry (x = 0 and 0.5). The phase evolution of the systems with the milling time was analyzed using X-ray diffraction. Thermal stability of the final products was studied using differential scanning calorimetry. Room temperature ⁵⁷Fe Mössbauer spectroscopy was used to follow the changes in the Fe environments. A paramagnetic Co-based amorphous phase developed in both alloys as milling progressed. However, while the presence of Si stabilized the Mn-type phase, mechanical recrystallization was observed in a Si-free composition leading to the formation of a MnCo(Fe)Ge intermetallic (Pnma space group) with a crystal size of 7 ± 1 nm. Mössbauer results indicate that Fe atoms migrate from the initial bcc phase to the amorphous and intermetallic phases. Full article

(This article belongs to the Special Issue Mechanical Alloying: Processing and Materials)

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9 pages, 3532 KiB

Open AccessArticle

Microstructure and Compressive Behavior of Al–Y₂O₃ Nanocomposites Prepared by Microwave-Assisted Mechanical Alloying

by Manohar Reddy Mattli, R. A. Shakoor, Penchal Reddy Matli and Adel Mohamed Amer Mohamed

Metals 2019, 9(4), 414; https://doi.org/10.3390/met9040414 - 05 Apr 2019

Cited by 30 | Viewed by 3735

Abstract

In this study, Al–Y₂O₃ nanocomposites were synthesized via mechanical alloying and microwave-assisted sintering. The effect of different levels of yttrium oxide on the microstructural and mechanical properties of the Al–Y₂O₃ nanocomposites were investigated. The density of the [...] Read more.

In this study, Al–Y₂O₃ nanocomposites were synthesized via mechanical alloying and microwave-assisted sintering. The effect of different levels of yttrium oxide on the microstructural and mechanical properties of the Al–Y₂O₃ nanocomposites were investigated. The density of the Al–Y₂O₃ nanocomposites increased with increasing Y₂O₃ volume fraction in the aluminum matrix, while the porosity decreased. Scanning electron microscopy analysis of the nanocomposites showed the homogeneous distribution of the Y₂O₃ nanoparticles in the aluminum matrix. X-ray diffraction analysis revealed the presence of yttria particles in the Al matrix. The mechanical properties of the Al–Y₂O₃ nanocomposites increased as the addition of yttria reached to 1.5 vol. % and thereafter decreased. The microhardness first increased from 38 Hv to 81 Hv, and then decreased to 74 ± 4 Hv for 1.5 vol. % yttria. The Al–1.5 vol. % Y₂O₃ nanocomposite exhibited the best ultimate compressive strength and yielded a strength of 359 ± 7 and 111 ± 5 MPa, respectively. The Al–Y₂O₃ nanocomposites showed higher hardness, yield strength, and compressive strength than the microwave-assisted mechanically alloyed pure Al. Full article

(This article belongs to the Special Issue Mechanical Alloying: Processing and Materials)

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Review

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11 pages, 1794 KiB

Open AccessFeature PaperReview

Mechanical Alloying of Elemental Powders into Nanocrystalline (NC) Fe-Cr Alloys: Remarkable Oxidation Resistance of NC Alloys

by R. K. Singh Raman

Metals 2021, 11(5), 695; https://doi.org/10.3390/met11050695 - 23 Apr 2021

Cited by 8 | Viewed by 1929

Abstract

Mechanical alloying is among the few cost effective techniques for synthesizing nanocrystalline alloy powders. This article reviews mechanical alloying or ball-milling of (NC) powders of Fe-Cr alloys of different compositions, and the remarkable oxidation resistance of the NC alloy. The article also reviews [...] Read more.

Mechanical alloying is among the few cost effective techniques for synthesizing nanocrystalline alloy powders. This article reviews mechanical alloying or ball-milling of (NC) powders of Fe-Cr alloys of different compositions, and the remarkable oxidation resistance of the NC alloy. The article also reviews challenges in thermal processing of the mechanically alloyed powders (such as compaction into monolithic mass) and means to overcome the challenges. Full article

(This article belongs to the Special Issue Mechanical Alloying: Processing and Materials)

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26 pages, 10294 KiB

Open AccessFeature PaperReview

A Comprehensive Review on Hydrogen Absorption Behaviour of Metal Alloys Prepared through Mechanical Alloying

by Thabang Ronny Somo, Thabiso Carol Maponya, Moegamat Wafeeq Davids, Mpitloane Joseph Hato, Mykhaylo Volodymyrovich Lototskyy and Kwena Desmond Modibane

Metals 2020, 10(5), 562; https://doi.org/10.3390/met10050562 - 26 Apr 2020

Cited by 30 | Viewed by 5541

Abstract

Hydride-forming alloys are currently considered reliable and suitable hydrogen storage materials because of their relatively high volumetric densities, and reversible H₂ absorption/desorption kinetics, with high storage capacity. Nonetheless, their practical use is obstructed by several factors, including deterioration and slow hydrogen absorption/desorption [...] Read more.

Hydride-forming alloys are currently considered reliable and suitable hydrogen storage materials because of their relatively high volumetric densities, and reversible H₂ absorption/desorption kinetics, with high storage capacity. Nonetheless, their practical use is obstructed by several factors, including deterioration and slow hydrogen absorption/desorption kinetics resulting from the surface chemical action of gas impurities. Lately, common strategies, such as spark plasma sintering, mechanical alloying, melt spinning, surface modification and alloying with other elements have been exploited, in order to overcome kinetic barriers. Through these techniques, improvements in hydriding kinetics has been achieved, however, it is still far from that required in practical application. In this review, we provide a critical overview on the effect of mechanical alloying of various metal hydrides (MHs), ranging from binary hydrides (CaH₂, MgH₂, etc) to ternary hydrides (examples being Ti-Mn-N and Ca-La-Mg-based systems), that are used in solid-state hydrogen storage, while we also deliver comparative study on how the aforementioned alloy preparation techniques affect H₂ absorption/desorption kinetics of different MHs. Comparisons have been made on the resultant material phases attained by mechanical alloying with those of melt spinning and spark plasma sintering techniques. The reaction mechanism, surface modification techniques and hydrogen storage properties of these various MHs were discussed in detail. We also discussed the remaining challenges and proposed some suggestions to the emerging research of MHs. Based on the findings obtained in this review, the combination of two or more compatible techniques, e.g., synthesis of metal alloy materials through mechanical alloying followed by surface modification (metal deposition, metal-metal co-deposition or fluorination), may provide better hydriding kinetics. Full article

(This article belongs to the Special Issue Mechanical Alloying: Processing and Materials)

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