The ball to powder ratio (BPR) dependent morphology and microstructure of tungsten powder refined by ball milling

Wu, Zefeng; Liang, Yanxiang; Fan, Yu; Wang, P.P.; Du, Jun; Zhao, Yunbiao; Fu, Engang

doi:10.1016/j.powtec.2018.07.094

Cited by 25 publications

(18 citation statements)

References 38 publications

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“…Initially, the milled powders coarsened for times of up to 4 h and accompanied by a transition in the particle morphologies from spherical for the W feedstock powder, as shown in the scanning electron micrograph in Figure 5b, to platelet-like geometries in Figure 5c. This morphological transition is consistent with the study by Wu et al [16] on the effect of media-to-powder ratio and indicative of a high rate of cold welding [17] combined with deformation along preferred slip systems in the coarse grain W powders [18]. Milling for additional time produced a rapid reduction in the particle size between 4 and 6 h, which we attributed to the dominant mechanism shifting toward fracture due to refinement of the grain size during this period, as shown in Figure 2b.…”

Section: Texture Evolution and Its Implications For Powder Morphologiessupporting

confidence: 94%

“…Microstructures produced via planetary ball milling ultimately depend on the characteristics of the particle impact (e.g., energy, frequency, etc. ), which are dictated by the processing parameters, including mediato-powder ratio, milling speed, atmosphere, temperature, total effective time (sometimes including intermittent off time measured by an effective duty cycle), and the selected process control agent (PCA) [15][16][17][18]. In addition to the high-volume fraction of grain boundaries intrinsic to the nanocrystalline state produced via high-energy ball milling, processed powders also contain an appreciable number of other defects including point defects, stacking faults, dislocations, and shear bands [19].…”

Section: Introductionmentioning

confidence: 99%

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Microstructural Transitions during Powder Metallurgical Processing of Solute Stabilized Nanostructured Tungsten Alloys

Olynik

Cheng

Sprouster

et al. 2022

Metals

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Exploiting grain boundary engineering in the design of alloys for extreme environments provides a promising pathway for enhancing performance relative to coarse-grained counterparts. Due to its attractive properties as a plasma facing material for fusion devices, tungsten presents an opportunity to exploit this approach in addressing the significant materials challenges imposed by the fusion environment. Here, we employ a ternary alloy design approach for stabilizing W against recrystallization and grain growth while simultaneously enhancing its manufacturability through powder metallurgical processing. Mechanical alloying and grain refinement in W-10 at.% Ti-(10,20) at.% Cr alloys are accomplished through high-energy ball milling with transitions in the microstructure mapped as a function of milling time. We demonstrate the multi-modal nature of the resulting nanocrystalline grain structure and its stability up to 1300 °C with the coarser grain size population correlated to transitions in crystallographic texture that result from the preferred slip systems in BCC W. Field-assisted sintering is employed to consolidate the alloy powders into bulk samples, which, due to the deliberately designed compositional features, are shown to retain ultrafine grain structures despite the presence of minor carbides formed during sintering due to carbon impurities in the ball-milled powders.

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Section: Texture Evolution and Its Implications For Powder Morphologiessupporting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Microstructural Transitions during Powder Metallurgical Processing of Solute Stabilized Nanostructured Tungsten Alloys

Olynik

Cheng

Sprouster

et al. 2022

Metals

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“…Thus, these results indicate the complete conversion of Cu(OH) 2 into CuO with only 20 min of milling. The charge ratio implies directly the reaction time since the higher the charge ratio is, the higher the frequency of the shocks and consequently the energy released during the milling are. , However, increasing the charge ratio too much is not always the answer because it may provide an undesired material amorphization . No precursor phases were detected when the reactions were performed at 1500 rpm (MCS-5) with 20 min of milling.…”

Section: Resultsmentioning

confidence: 99%

Improved Mechanochemical Fabrication of Copper(II) Oxide Nanoparticles with Low E-Factor. Efficient Catalytic Activity for Nitroarene Reduction in Aqueous Medium

Schio

Soares

Machado³

et al. 2021

ACS Sustainable Chem. Eng.

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Copper(II) oxide nanoparticles (CuONPs) have become an essential material with a wide range of applications in different areas. Although different methodologies are available to fabricate CuONPs, most of them are solvent based, which generate a high amount of waste. Therefore, synthetic methodologies under dry conditions are an interesting alternative for seeking high yields, scale-up, and waste minimization. In this work, we describe an improved and lower environmental impact methodology to synthesize CuONPs through one-step high-energy mechanochemical milling under dry conditions. The methodology proved itself efficient to prepare CuONPs in gram-scale quantities, with 88% yield after 20 min at 1000 rpm and in the absence of additional heat treatment. The CuONPs exhibited a predominantly quasi-spherical morphology and an average size of 7.84 ± 2.08 nm. The nanoparticles showed a surface area of 68 ± 10 m2 g–1 and an energy gap value of 2.28 eV. The catalytic activity of the mechanochemically obtained CuONPs was successfully explored for nitroarene reduction in an aqueous medium. Conversion and selectivity both reached 99% for eight nitroarene examples. The catalyst was reused up to five times in consecutive runs without a significant decrease in the catalytic activity.

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“…The high ductility of Al and the heat generated during milling due to the high impact collision forces between the balls and the Al powders resulted in Al agglomeration. As a result, welding became more dominant than fracturing (Suryanarayana, 2019;Wu et al, 2018). The significant increase in the average particle size of the initial fine powders from 15 μm to 0.45 mm after 2 h of milling, indicated that cold welding of the Al particles was clearly activated, see Figure 2B.…”

Section: Conventional Milling Vialmentioning

confidence: 99%

The Effect of the Milling Vial Shape on the In-Situ Consolidation of a Nanocrystalline Al-Li-GNPs Nanocomposite Synthesized by Room Temperature Ball-Milling

Ahmad

Youssef

2022

Front. Mater.

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Several studies investigating the ball-milling of ductile face-centered cubic metals have reported a so-called in-situ consolidation phenomenon where the milled powder is also consolidated during the milling process. Thus, instead of refined powders or agglomerated particles, the formation of spherical bulk particles of the milled material is reported using a combination of cryomilling and room temperature milling processes. In this study, we studied the effect of the milling vial shape on the in-situ consolidation of a graphene nanoplatelets (GNPs) reinforced aluminum-lithium (Al-Li) matrix nanocomposite for the first time. An in-situ consolidated nanometric Al-Li-GNPs nanocomposite with an average grain size of 48 nm and high hardness of 1.48 GPa was attained after only 8 h of room-temperature milling. The results presented suggest that dense nanostructured composites can be prepared by in-situ consolidation during a one-step milling process and subsequently investigated in order to analyze their mechanical behavior. This allows for the intrinsic mechanical behavior of the synthesized material to be examined without the interference of subsequent high-temperature consolidation processes, thus avoiding unwanted structural changes such as grain growth and second phase formations.

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The ball to powder ratio (BPR) dependent morphology and microstructure of tungsten powder refined by ball milling

Cited by 25 publications

References 38 publications

Microstructural Transitions during Powder Metallurgical Processing of Solute Stabilized Nanostructured Tungsten Alloys

Microstructural Transitions during Powder Metallurgical Processing of Solute Stabilized Nanostructured Tungsten Alloys

Improved Mechanochemical Fabrication of Copper(II) Oxide Nanoparticles with Low E-Factor. Efficient Catalytic Activity for Nitroarene Reduction in Aqueous Medium

The Effect of the Milling Vial Shape on the In-Situ Consolidation of a Nanocrystalline Al-Li-GNPs Nanocomposite Synthesized by Room Temperature Ball-Milling

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