On the crystallite size refinement of ZrB2 by high-energy ball-milling in the presence of SiC

In the present work, multiwalled carbon nanotubes (MWNTs) were synthesized by electric arc discharge method in open air atmosphere. The synthesized nanotubes were subjected to multistep purification followed by characterization using Raman spectroscopy and transmission electron microscopy (TEM). These carbon nanotubes (CNTs) have inner and outer diameters of the order of 3.5 nm and 16 nm with an aspect ratio of 63. AA 4032 nanocomposites reinforced with MWNTs were produced by high energy ball milling using elemental powder mixtures. X-ray diffraction (XRD) and scanning electron microscope (SEM) studies showed different phases of composite with and without CNTs. The crystallite size and lattice strain were calculated using an anisotropic model of Williamson–Hall peak broadening analysis, which showed in decreased crystallite size with increasing milling time. TEM studies reveal that the MWNTs were uniformly distributed in the matrix. Thermal stability of the nanocrystalline powders was studied using a differential thermal analyzer (DTA). The mechanically alloyed powders were consolidated using a novel method called equal channel angular pressing (ECAP) at room temperature. The consolidated samples were sintered at 480 °C in argon atmosphere for 90 min. ECAP method was investigated as an alternative to conventionally sintered powder composites. CNT addition has shown significant improvement in the hardness of the system, even though the observed density is relatively low compared with a base alloy. Thus, the results show that ECAP enables sufficient shear deformation results in good metallurgical bonds between particles at lower compaction pressures. Hence, it is proven that ECAP can be effectively used as one of the consolidation technique especially for powders that are difficult to consolidate by other means.

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Hydrogen in Metallic Nanostructures

Materials Science Forum ◽

10.4028/www.scientific.net/msf.555.327 ◽

2007 ◽

Vol 555 ◽

pp. 327-334 ◽

Cited By ~ 1

Author(s):

R.A. Andrievski

Keyword(s):

Physical Properties ◽

Crystallite Size ◽

Ball Milling ◽

High Energy ◽

Structural Features ◽

Metallic Nanostructures ◽

High Energy Ball Milling ◽

Universal Method ◽

Characterization Methods ◽

Energy Ball

Features of hydrogen nanostructure synthesis are described as applied to metals (Mg and Pd) and intermetallics (Mg2Ni, FeTi and LaNi5). Attention is focused on the high-energy ball milling as a universal method for hydrogen nanostructure preparation. The effect of crystallite size, absorption/desorption properties of Pd - H2, Mg2Ni - H2, TiFe - H2 and Mg - H2 systems are characterized in detail. Structural features and some physical properties of nanohydrides studied by different independent characterization methods are considered.

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High-Energy Ball Milling Conditions in Formation of NiTiCu Shape Memory Alloys

Microscopy and Microanalysis ◽

10.1017/s143192762101271x ◽

2021 ◽

pp. 1-7

Author(s):

Tomasz Goryczka ◽

Piotr Salwa ◽

Maciej Zubko

Keyword(s):

Chemical Composition ◽

Shape Memory ◽

Crystallite Size ◽

Ball Milling ◽

Average Crystallite Size ◽

High Energy ◽

High Energy Ball Milling ◽

Energy Ball ◽

Average Size ◽

Grinding Time

The properties and the shape memory effect depend, among other things, on chemical composition, as well as the method of shape memory alloy (SMA) production. One of the manufacturing methods that leads to the amorphous/nanocrystalline SMA is high-energy ball milling combined with annealing. Using this technique, an SMA memory alloy, with the nominal chemical composition of Ni25Ti50Cu25, was produced from commercial elemental powders (purity −99.7%). The structure and morphology were characterized (at the various stages of its production) by the use of X-ray diffraction, as well as electron microscopy (both scanning and transmission). Choosing the appropriate grinding time made it possible to produce an NiTiCu alloy with a different crystallite size. Its average size changed from 6.5 nm (after 50 h) to about 2 nm (100 h). Increasing the grinding time up to 140 h resulted in the formation of areas that showed the B19 martensite and the Ti2(Ni,Cu) phase with the average crystallite size of about 6 nm (as milled). After crystallization, the average size increased to 11 nm.

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High Energy Planetary Ball Milling of SiC Powders

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.351.7 ◽

2007 ◽

Vol 351 ◽

pp. 7-14 ◽

Cited By ~ 1

Author(s):

Yu Bai Pan ◽

Zheng Ren Huang ◽

Dong Liang Jiang ◽

Léo Mazerolles ◽

D. Michel ◽

...

Keyword(s):

Crystallite Size ◽

Ball Milling ◽

Average Crystallite Size ◽

High Energy ◽

High Energy Ball Milling ◽

Fine Powders ◽

Sic Ceramics ◽

Sem And Tem ◽

Planetary Ball Milling ◽

Energy Ball

The effects of high-energy ball milling on SiC powders were studied using a planetary apparatus. Conditions to obtain nanostructured SiC powders with an average crystallite size of 4 nm were determined and powders were characterized by XRD, SEM and TEM analyses. This process was applied to prepare fine powders leading to dense SiC ceramics by sintering at 1900oC for 30 minutes under 30 MPa in argon.

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Enhancement in Thermoelectric Figure-of-merit of n-type Si-Ge Alloy Synthesized Employing High Energy Ball Milling and Spark Plasma Sintering

MRS Proceedings ◽

10.1557/opl.2012.1731 ◽

2013 ◽

Vol 1490 ◽

pp. 51-56 ◽

Cited By ~ 5

Author(s):

Sivaiah Bathula ◽

M. Jayasimhadri ◽

Ajay Dhar ◽

M. Saravanan ◽

D. K. Misra ◽

...

Keyword(s):

Crystallite Size ◽

Ball Milling ◽

Spark Plasma Sintering ◽

Figure Of Merit ◽

High Energy ◽

High Energy Ball Milling ◽

Sintered Alloy ◽

Plasma Sintering ◽

Spark Plasma ◽

Energy Ball

ABSTRACTIn the present study, we report the enhancement in figure-of-merit (ZT) of nanostructured n-type Silicon-Germanium (Si80Ge20) thermoelectric alloy synthesized using high energy ball milling followed by spark plasma sintering (SPS). After 90 h of ball milling of elemental powders of Si, Ge and P (2 at.%), a complete dissolution of Ge in Si matrix has been observed forming the nanostructured n-type Si80Ge20 alloy powder. X-ray diffraction analysis (XRD) confirmed the crystallite size of the host matrix (Si) to be ∼7 nm and also indicated the formation of an additional phase of SiP nano-precipitates after SPS. HR-TEM analysis revealed that the nano-grained network was retained post-sintering with a crystallite size of size of 9 nm and also confirmed the SiP precipitates formation with a size of 4 to 6 nm. As a result, a very low thermal conductivity of ∼2.3W/mK at 900°C has been observed for Si80Ge20 alloy primarily due to scattering of phonons by nanostructured grains and nano-scaled SiP precipitates which further contribute to this scattering mechanism. Electrical conductivity values of SiGe sintered alloy are slightly lower to that of reported values in literature. This was attributed to the formation of SiP which creates a compositional difference between the grain boundary region and the grain region, leading to a chemical potential difference at interface and the grain region. Figure-of-merit (ZT) of n-type Si80Ge20 nanostructured alloy was found to be ≈1.5 at 900°C, which is the highest reported so far at this temperature.

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Evolution of crystallite size, lattice parameter and internal strain in Al precipitates during high energy ball milling of partly amorphous Al87Ni8La5 alloy

Materials Science and Engineering A ◽

10.1016/j.msea.2014.03.004 ◽

2014 ◽

Vol 604 ◽

pp. 27-33 ◽

Cited By ~ 16

Author(s):

M. Dittrich ◽

G. Schumacher

Keyword(s):

Crystallite Size ◽

Ball Milling ◽

High Energy ◽

Lattice Parameter ◽

High Energy Ball Milling ◽

Internal Strain ◽

Energy Ball

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102213 Use of High Energy Ball Milling on the Sintering Optimization of Alumina Ceramics

Materials Science Forum ◽

10.4028/www.scientific.net/msf.660-661.701 ◽

2010 ◽

Vol 660-661 ◽

pp. 701-706

Author(s):

Helio R. Simoni ◽

Eduardo Saito ◽

Claudinei dos Santos ◽

Felipe Antunes Santos ◽

Alfeu Saraiva Ramos ◽

...

Keyword(s):

Crystallite Size ◽

Ball Milling ◽

Milling Time ◽

High Energy ◽

High Energy Ball Milling ◽

Green Density ◽

Alumina Ceramics ◽

X Ray Diffraction ◽

X Ray ◽

Energy Ball

In this work, the effect of the milling time on the densification of the alumina ceramics with or without 5wt.%Y2O3, is evaluated, using high-energy ball milling. The milling was performed with different times of 0, 2, 5 or 10 hours. All powders, milled at different times, were characterized by X-Ray Diffraction presenting a reduction of the crystalline degree and crystallite size as function of the milling time increasing. The powders were compacted by cold uniaxial pressing and sintered at 1550°C-60min. Green density of the compacts presented an increasing as function of the milling time and sintered samples presented evolution on the densification as function of the reduction of the crystallite size of the milled powders.

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