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3 pages, 195 KiB

Open AccessEditorial

Novel Materials Synthesis by Mechanical Alloying/Milling

by Joan-Josep Suñol and Lluisa Escoda

Materials 2022, 15(19), 6973; https://doi.org/10.3390/ma15196973 - 8 Oct 2022

Cited by 4 | Viewed by 1576

Abstract

Mechanical alloying (MA) and mechanical milling (MM) are based on the ball milling technique/procedure [...] Full article

(This article belongs to the Special Issue Novel Materials Synthesis by Mechanical Alloying/Milling)

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13 pages, 2385 KiB

Open AccessArticle

Study of the Influence of Sintering Atmosphere and Mechanical Activation on the Synthesis of Bulk Ti₂AlN MAX Phase Obtained by Spark Plasma Sintering

by Christopher Salvo, Ernesto Chicardi, Cristina García-Garrido, Rosalía Poyato, José A. Jiménez and R. V. Mangalaraja

Materials 2021, 14(16), 4574; https://doi.org/10.3390/ma14164574 - 14 Aug 2021

Cited by 6 | Viewed by 2227

Abstract

The influence of the mechanical activation process and sintering atmosphere on the microstructure and mechanical properties of bulk Ti₂AlN has been investigated. The mixture of Ti and AlN powders was prepared in a 1:2 molar ratio, and a part of this [...] Read more.

The influence of the mechanical activation process and sintering atmosphere on the microstructure and mechanical properties of bulk Ti₂AlN has been investigated. The mixture of Ti and AlN powders was prepared in a 1:2 molar ratio, and a part of this powder mixture was subjected to a mechanical activation process under an argon atmosphere for 10 h using agate jars and balls as milling media. Then, the sintering and production of the Ti₂AlN MAX phase were carried out by Spark Plasma Sintering under 30 MPa with vacuum or nitrogen atmospheres and at 1200 °C for 10 min. The crystal structure and microstructure of consolidated samples were characterized by X-ray Diffraction, Scanning Electron Microscopy, and Energy Dispersive X-ray Spectroscopy. The X-ray diffraction patterns were fitted using the Rietveld refinement for phase quantification and determined their most critical microstructural parameters. It was determined that by using nitrogen as a sintering atmosphere, Ti₄AlN₃ MAX phase and TiN were increased at the expense of the Ti₂AlN. In the samples prepared from the activated powders, secondary phases like Ti₅Si₃ and Al₂O₃ were formed. However, the higher densification level presented in the sample produced by using both nitrogen atmosphere and MAP powder mixture is remarkable. Moreover, the high-purity Ti₂AlN zone of the MAX-1200 presented a hardness of 4.3 GPa, and the rest of the samples exhibited slightly smaller hardness values (4.1, 4.0, and 4.2 GPa, respectively) which are matched with the higher porosity observed on the SEM images. Full article

(This article belongs to the Special Issue Novel Materials Synthesis by Mechanical Alloying/Milling)

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12 pages, 2124 KiB

Open AccessArticle

Structural, Thermal and Magnetic Analysis of Fe₇₅Co₁₀Nb₆B₉ and Fe₆₅Co₂₀Nb₆B₉ Nanostructured Alloys

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

Materials 2021, 14(16), 4542; https://doi.org/10.3390/ma14164542 - 12 Aug 2021

Cited by 9 | Viewed by 1821

Abstract

Two nanocrystalline ferromagnetic alloys of the Fe-Co-Nb-B system have been produced by mechanical alloying (MA). Their microstructure, thermal behavior and magnetic response were checked by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and vibrating sample magnetometry (VSM). After 80 h of MA, the [...] Read more.

Two nanocrystalline ferromagnetic alloys of the Fe-Co-Nb-B system have been produced by mechanical alloying (MA). Their microstructure, thermal behavior and magnetic response were checked by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and vibrating sample magnetometry (VSM). After 80 h of MA, the alloys were nanostructured (bcc-Fe(Co)-rich phase). As the Co content increases, the density of the dislocations decreases. Besides, a higher concentration of Co causes an increase in the activation energy of the crystallization process. The calculated energies, 267 and 332 kJ/mol, are associated to the crystalline growth of the bcc-Fe-rich phase. The Co content of the samples has no effect on the value of the saturation magnetization, whereas the coercivity is lower in the alloy containing less Co. Samples were compacted and heat-treated. Optimal annealing reduces the coercivity by a factor of two. Results were compared with the data of Fe-Nb-B and Fe-Ni-Nb-B alloys. Full article

(This article belongs to the Special Issue Novel Materials Synthesis by Mechanical Alloying/Milling)

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14 pages, 1845 KiB

Open AccessArticle

High-Energy Mechanical Milling-Driven Reamorphization in Glassy Arsenic Monoselenide: On the Path of Tailoring Special Molecular-Network Glasses

by Yaroslav Shpotyuk, Pavlo Demchenko, Oleh Shpotyuk, Valentina Balitska, Catherine Boussard-Pledel, Bruno Bureau, Zdenka Lukáčová Bujňáková and Peter Baláž

Materials 2021, 14(16), 4478; https://doi.org/10.3390/ma14164478 - 10 Aug 2021

Cited by 11 | Viewed by 1665

Abstract

The impact of high-energy milling on glassy arsenic monoselenide g-AsSe is studied with X-ray diffraction applied to diffuse peak-halos proper to intermediate- and extended-range ordering revealed in first and second sharp diffraction peaks (FSDP and SSDP). A straightforward interpretation of this effect is [...] Read more.

The impact of high-energy milling on glassy arsenic monoselenide g-AsSe is studied with X-ray diffraction applied to diffuse peak-halos proper to intermediate- and extended-range ordering revealed in first and second sharp diffraction peaks (FSDP and SSDP). A straightforward interpretation of this effect is developed within the modified microcrystalline approach, treating “amorphous” halos as a superposition of the broadened Bragg diffraction reflexes from remnants of some inter-planar correlations, supplemented by the Ehrenfest diffraction reflexes from most prominent inter-molecular and inter-atomic correlations belonging to these quasi-crystalline remnants. Under nanomilling, the cage-like As₄Se₄ molecules are merely destroyed in g-AsSe, facilitating a more polymerized chain-like network. The effect of nanomilling-driven molecular-to-network reamorphization results in a fragmentation impact on the correlation length of FSDP-responsible entities (due to an increase in the FSDP width and position). A breakdown in intermediate-range ordering is accompanied by changes in extended-range ordering due to the high-angular shift and broadening of the SSDP. A breakdown in the intermediate-range order is revealed in the destruction of most distant inter-atomic correlations, which belong to remnants of some quasi-crystalline planes, whereas the longer correlations dominate in the extended-range order. The microstructure scenarios of milling-driven reamorphization originated from the As₄Se₄ molecule, and its network derivatives are identified with an ab initio quantum-chemical cluster modeling code (CINCA). Full article

(This article belongs to the Special Issue Novel Materials Synthesis by Mechanical Alloying/Milling)

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23 pages, 18707 KiB

Open AccessArticle

Investigation of the Microstructure and Compressibility of Biodegradable Fe-Mn-Cu/W/Co Nanostructured Alloy Powders Synthesized by Mechanical Alloying

by Hany R. Ammar, Subbarayan Sivasankaran and Abdulaziz S. Alaboodi

Materials 2021, 14(11), 3088; https://doi.org/10.3390/ma14113088 - 4 Jun 2021

Cited by 12 | Viewed by 2335

Abstract

In this research work, the nanostructured Fe-Mn (BM0), Fe-Mn-Cu (BM1), Fe-Mn-W (BM2), and Fe-Mn-Co (BM3) biodegradable alloys were successfully synthesized using mechanical alloying. The microstructure of the synthesized alloys was examined using XRD, SEM equipped with EDS, and HRTEM techniques. The results obtained [...] Read more.

In this research work, the nanostructured Fe-Mn (BM0), Fe-Mn-Cu (BM1), Fe-Mn-W (BM2), and Fe-Mn-Co (BM3) biodegradable alloys were successfully synthesized using mechanical alloying. The microstructure of the synthesized alloys was examined using XRD, SEM equipped with EDS, and HRTEM techniques. The results obtained based on these techniques confirmed the development of nanostructured BM0, BM1, BM2, and BM3 alloys and homogenous solid solutions with an even elemental dispersion. The compressibility of the synthesized alloys was investigated experimentally and empirically in the as-milled conditions and after applying a stress relief treatment (150 °C for 1 h). The load applied for compaction experiments ranged from 25–1100 MPa with a rate of 1 mm/min. According to the experimentation performed in the current study, the relative density of the as-milled BM0, BM1, BM2, and BM3 alloys was 72.90% and 71.64%, 72.32%, and 72.03%, respectively. After applying the stress relief treatment, the density was observed to increase to 75.23%, 77.10%, 72.65%, and 72.86% for BM0-S, BM1-S, BM2-S and BM3-S samples, respectively. A number of compaction models were tested to identify the optimum models for predicting the compressibility behavior of nanostructured Fe-Mn, Fe-Mn-Cu, Fe-Mn-W, and Fe-Mn-Co alloys in the as-milled and stress-relieved conditions. Full article

(This article belongs to the Special Issue Novel Materials Synthesis by Mechanical Alloying/Milling)

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15 pages, 20981 KiB

Open AccessArticle

Effect of Mo and Ta on the Mechanical and Superelastic Properties of Ti-Nb Alloys Prepared by Mechanical Alloying and Spark Plasma Sintering

by Damian Kalita, Łukasz Rogal, Katarzyna Berent, Anna Góral and Jan Dutkiewicz

Materials 2021, 14(10), 2619; https://doi.org/10.3390/ma14102619 - 17 May 2021

Cited by 8 | Viewed by 2244

Abstract

The effect of ternary alloying elements (Mo and Ta) on the mechanical and superelastic properties of binary Ti-14Nb alloy fabricated by the mechanical alloying and spark plasma sintering was investigated. The materials were prepared in two ways: (i) by substituting Nb in base [...] Read more.

The effect of ternary alloying elements (Mo and Ta) on the mechanical and superelastic properties of binary Ti-14Nb alloy fabricated by the mechanical alloying and spark plasma sintering was investigated. The materials were prepared in two ways: (i) by substituting Nb in base Ti-14Nb alloy by 2 at.% of the ternary addition, giving the following compositions: Ti-8Nb-2Mo and Ti-12Nb-2Ta and (ii) by adding 2 at.% of the ternary element to the base alloy. The microstructures of the materials consisted of the equiaxed β-grains and fine precipitations of TiC. The substitution of Nb by both Mo and Ta did not significantly affect the mechanical properties of the base Ti-14Nb alloy, however, their addition resulted in a decrease of yield strength and increase of plasticity. This was associated with the occurrence of the {332} <113> twinning that was found during the in-situ observations. The elevated concentration of interstitial elements (oxygen and carbon) lead to the occurrence of stress-induced martensitic transformation and twinning mechanisms at lower concentration of β-stabilizers in comparison to the conventionally fabricated materials. The substitution of Nb by Mo, and Ta caused the slight improvement of the superelastic properties of the base Ti-14Nb alloy, whereas their addition deteriorated the superelasticity. Full article

(This article belongs to the Special Issue Novel Materials Synthesis by Mechanical Alloying/Milling)

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13 pages, 8426 KiB

Open AccessFeature PaperArticle

Investigation of the Critical Behavior, Magnetocaloric Effect and Hyperfine Structure in the Fe₇₂Nb₈B₂₀ Powders

by Safia Alleg, Thaounza Chabi, Nadia Bensebaa, Joan Saurina, Lluisa Escoda, El-Kebir Hlil and Joan-Josep Suñol

Materials 2020, 13(20), 4476; https://doi.org/10.3390/ma13204476 - 9 Oct 2020

Cited by 5 | Viewed by 1841

Abstract

Microstructure as well as magnetic, thermal and magnetocaloric properties of the mechanically alloyed Fe₇₂Nb₈B₂₀ powders have been investigated by means of Mössbauer spectrometry, differential scanning calorimetry (DSC), and magnetic measurements. The Mössbauer spectrometry results showed the formation of [...] Read more.

Microstructure as well as magnetic, thermal and magnetocaloric properties of the mechanically alloyed Fe₇₂Nb₈B₂₀ powders have been investigated by means of Mössbauer spectrometry, differential scanning calorimetry (DSC), and magnetic measurements. The Mössbauer spectrometry results showed the formation of nanostructured Fe(B) and Fe(Nb) solid solutions, Fe₂B boride, and an amorphous phase. The endothermic and exothermic peaks that are observed in the DSC curves might be related to the Curie temperature, and the crystallization of the amorphous phase, respectively. The critical exponent values around the magnetic phase transition of the amorphous phase (T_C = 480 K), are deduced from the modified Arrott plots, Kouvel−Fisher curves and critical isotherm examination. The calculated values (β = 0.457 ± 0.012, γ = 0.863 ± 0.136 and δ = 3.090 ± 0.004) are near to those of the mean field model, revealing a dominating role of magnetic order arising due to long-range ferromagnetic interactions, as the critical exponents are mean-field-like. The maximum entropy change and the refrigerant capacity values are 1.45 J/kg·K and 239 J/kg, respectively, under a magnetic field of 5 T. Full article

(This article belongs to the Special Issue Novel Materials Synthesis by Mechanical Alloying/Milling)

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11 pages, 2759 KiB

Open AccessFeature PaperArticle

Influence of Milling Time on the Homogeneity and Magnetism of a Fe₇₀Zr₃₀ Partially Amorphous Alloy: Distribution of Curie Temperatures

by Alejandro F. Manchón-Gordón, Jhon J. Ipus, Javier S. Blázquez, Clara F. Conde and Alejandro Conde

Materials 2020, 13(2), 490; https://doi.org/10.3390/ma13020490 - 20 Jan 2020

Cited by 13 | Viewed by 2984

Abstract

In this work, the mechanically alloyed Fe₇₀Zr₃₀ (at. %) composition has been used to study the influence of milling time on its homogeneity and magnetic properties. The microstructure and Fe environment results show the formation of an almost fully amorphous [...] Read more.

In this work, the mechanically alloyed Fe₇₀Zr₃₀ (at. %) composition has been used to study the influence of milling time on its homogeneity and magnetic properties. The microstructure and Fe environment results show the formation of an almost fully amorphous alloy after 50 h of milling in a mixture of pure 70 at. % Fe and 30 at. % Zr. The soft magnetic behavior of the samples enhances with the increase of the milling time, which is ascribed to the averaging out of the magnetocrystalline anisotropy as the crystal size decreases and the amorphous fraction increases. The formation of a non-perfectly homogenous system leads to a certain compositional heterogeneity, motivating the existence of a distribution of Curie temperatures. The parameters of the distribution (the average Curie temperature,

\bar{T_{C}}

, and the broadening of the distribution,

∆ T_{C}

) have been obtained using a recently reported procedure, based on the analysis of the approach towards the saturation curves and the magnetocaloric effect. The decrease of

∆ T_{C}

and the increase of

\bar{T_{C}}

with the milling time are in agreement with the microstructural results. As the remaining α-Fe phase decreases, the amorphous matrix is enriched in Fe atoms, enhancing its magnetic response. Full article

(This article belongs to the Special Issue Novel Materials Synthesis by Mechanical Alloying/Milling)

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