Microstructure and mechanical behavior of Al-xMg/5Al2O3 nanostructured composites

Abstract The effect of Mg content and milling time were investigated on the microstructure and microhardness values of Al-xMg/5Al2O3 (x = 0, 4, 8 and 12 wt %) nanostructured composite prepared via high energy milling technique. XRD results showed an acceleration of alloying process and formation of Al (Mg) ss by enhancing percentage of Mg element. Also, by increase in Mg percentage the grain size reduction was more considerable during milling treatment. Additionally, increment of the Mg content up to 12 wt%, causes the increase in micro-strain of the samples (from 0.31 to 0.82%). Increase in Mg concentration accelerates the mechanical milling process. According to SEM results a coaxial and circular morphology with a uniform distribution of powder particles has been formed. Up to 12 wt% (for each milling time), significant increase in microhardness (215 HV) was carried out due to solid solution hardening and crystallite refinement. From 10 to 15 h, a slight increase in microhardness up to 218 HV can be observed.

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MICROSTRUCTURE AND MAGNETIC PROPERTIES OF NANOSTRUCTURED Al2O3-20vol%Fe70Co30 COMPOSITE PREPARED BY HIGH ENERGY MECHANICAL MILLING

International Journal of Modern Physics B ◽

10.1142/s0217979209061937 ◽

2009 ◽

Vol 23 (06n07) ◽

pp. 1383-1388 ◽

Cited By ~ 2

Author(s):

MASLEEYATI YUSOP ◽

DELIANG ZHANG ◽

MARCUS WILSON ◽

NICK STRICKLAND

Keyword(s):

Grain Size ◽

Magnetic Properties ◽

Alloy Powder ◽

Milling Time ◽

High Energy ◽

Composite Powders ◽

Nanostructured Composite ◽

Alloy Particles ◽

Average Grain Size ◽

Microstructure And Magnetic Properties

Al 2 O 3-20 vol % Fe 70 Co 30 composite powders have been prepared by high energy ball milling a mixture of Al 2 O 3 powder and Fe 70 Co 30 alloy powder. The Fe 70 Co 30 alloy powder was also prepared by mechanical alloying of Fe and Co powders using the same process. The effects of milling duration from 8 to 48 hours on microstructure and magnetic properties of the nanostructured composite powders have been studied by means of X-ray Diffractometry (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometry (VSM). It was found that the nanostructured composite powder particles with irregular shapes and Fe 70 Co 30 alloy particles being embedded in them formed after 8 hours of milling. The average grain size of the Al 2 O 3 matrix reduced drastically to less than 18nm after 16 hours of milling. On the other hand, the embedded alloy particles demonstrated almost unchanged average grain size in the range of 14-15nm. Magnetic properties of the powder compacts at room temperature were measured from hysteresis curves, and show strong dependence of the milling time, with the coercivity increasing from 67.1 up to 127.9kOe with increasing the milling time from 8 to 48 hours. The possible microstructural reasons for this dependence are discussed.

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Microstructures and Functional Group Properties of Nano-Sized Chitosan Prepared by Ball Milling

Materials Science Forum ◽

10.4028/www.scientific.net/msf.948.192 ◽

2019 ◽

Vol 948 ◽

pp. 192-197

Author(s):

Kartika Sari ◽

Edi Suharyadi ◽

Roto Roto ◽

Kamsul Abraha

Keyword(s):

Grain Size ◽

Ball Milling ◽

Milling Time ◽

Functional Group ◽

High Energy ◽

Milling Process ◽

Sem Images ◽

Infra Red ◽

Group A ◽

The Fourier Transform

Nano-sized chitosan has been prepared by ball mill (High Energy Milling) with 1500 rpm to determine itsgrainz size and functional group. A nanopowder sample was prepared in the various milling time of the precusor. The milling time were 60, 120, 180, 240, 300 and 360 minutes. The Scanning Electron Microscopy (SEM)images indicated that the microstructures and grain size of as-prepared chitosan changed by increasing the milling time. The average of grain size is 15,1 nm. The Fourier Transform Infra-Red (FTIR) spectra showedthat the -OH bond shifted after milling process. The new C=O roups formedduring the milling process, because of the ordered microstructures in the nano-sized chitosan granules weredestroyed after ball millingThe surface area of the nano-sized chitosan was high, the particles tend to agglomerate since the ionic electrostatic could not prevent to form the agglomeration. The ball milling treatment was an effective method to reduce the grain size of chitosan, and functional groups will not automatically change during the milling process.

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Decomposition and Crystallization Induced by High-Energy Ball-Milling

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.119.1 ◽

2007 ◽

Vol 119 ◽

pp. 1-4 ◽

Cited By ~ 2

Author(s):

Young Soon Kwon ◽

Ji Soon Kim ◽

Cheol Eeh Kim

Keyword(s):

Grain Size ◽

Phase Transformation ◽

Ball Milling ◽

Milling Time ◽

High Energy ◽

Thermally Induced ◽

Average Grain Size ◽

Powder Particles ◽

Energy Ball ◽

Decomposition Behavior

Phase transformation induced by ball-milling was studied in this work. It was found that amorphous Fe90Zr10 ribbons undergo crystallization into BCC α-Fe(Zr) under milling in an AGO-2 mill. The decomposition degree of the amorphous phase increased with increasing milling time and intensity. Analyses of samples milled at different speeds suggested that the observed crystallization is a deformation-induced process rather than a thermally induced one. In addition, the decomposition behavior of a FeSn intermetallic under ball-milling was carefully studied. Upon milling a large amount of the FeSn intermetallic decomposed into Fe5Sn3 and FeSn2, where the average grain size of the product phases stayed nearly constant with milling-time. It is suggested that the mechanically driven decomposition of FeSn results from local melting of powder particles due to high temperature pulses during ball collisions.

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Mechanical Hardness as a Probe of Nanocrystalline Materials

MRS Proceedings ◽

10.1557/proc-362-253 ◽

1994 ◽

Vol 362 ◽

Cited By ~ 4

Author(s):

C. C. Koch ◽

T. D. Shen ◽

T. Malow ◽

O. Spaldon

Keyword(s):

Solid Solution ◽

Grain Size ◽

Grain Boundary ◽

Nanocrystalline Materials ◽

Size Dependence ◽

Solid Solution Hardening ◽

Solution Hardening ◽

Softening Effect ◽

Mechanical Hardness ◽

Solid Solution Softening

AbstractThe use of mechanical hardness as a probe of nanocrystalline materials is reviewed. The fact that the grain size dependence of hardness is very different for nanocrystalline materials compared to conventional (≥1 μm diameter) polycrystals suggests a different deformation mechanism may be operative in nanocrystalline materials. Hardness is useful for following the sintering, densification reactions of nanoparticles. Solid solution hardening in nanocrystalline alloys is found to be overwhelmed by the grain boundary hardening. If alloying decreases the grain boundary hardening, i.e. increases grain size, an apparent solid solution softening effect is observed.

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On the Orowan stress in intermetallic ODS alloys and its superposition with grain size and solid solution hardening

Zeitschrift für Metallkunde ◽

10.3139/146.101105 ◽

2005 ◽

Vol 96 (7) ◽

pp. 801-806

Author(s):

Holger Saage ◽

Martin Heilmaier ◽

Jürgen Eckert

Keyword(s):

Solid Solution ◽

Grain Size ◽

Solid Solution Hardening ◽

Solution Hardening ◽

Orowan Stress ◽

Ods Alloys

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Research of the Milling Time Influence on Ag-Cu Powder Particles Size Processed by Mechanical Alloying Route

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.188.382 ◽

2012 ◽

Vol 188 ◽

pp. 382-387 ◽

Cited By ~ 5

Author(s):

Oana Gîngu ◽

Claudiu Nicolicescu ◽

Gabriela Sima

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Mechanical Alloying ◽

Size Distribution ◽

Powder Mixture ◽

Milling Time ◽

High Energy ◽

Milling Process ◽

Future Research ◽

Powder Particles

This research focuses on Ag-Cu powder particles processing by mechanical alloying (MA) route. The powder mixture is representative for the eutectic composition, respectively 72%wt. Ag + 28% wt. Cu. The milling process is developed in high energy ball mill Pulverisette 6, using different size for the milling balls, in wet conditions for 80 hours. One of the most important parameter studied in this research is the particle size distribution of the processed powder mixture. Thus, it changes along the milling time, from 10…75 µm at the beginning of MA process up to (60 – 80) nm at 80 h. The milling parameters will be optimized in future research depending on the particle size distribution related with thermophysical and thermodynamic properties focused on electrical and optical properties improvement.

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Structural and ferroelectrical properties of bismuth titanate ceramic powders prepared by mechanically assisted synthesis

Science of Sintering ◽

10.2298/sos0702177l ◽

2007 ◽

Vol 39 (2) ◽

pp. 177-184 ◽

Cited By ~ 7

Author(s):

Z.Z. Lazarevic ◽

N.Z. Romcevic ◽

M. Todorovic ◽

B.D. Stojanovic

Keyword(s):

Grain Size ◽

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Milling Time ◽

Bismuth Titanate ◽

Ferroelectric Properties ◽

High Energy ◽

Milling Process ◽

Oxide Mixture

Nanosized bismuth titanate, Bi4Ti3O12, was prepared via a high-energy ball milling process through mechanically assisted synthesis directly from the oxide mixture of Bi2O3 and TiO2. The Bi4Ti3O12 phase started to form after 1 h of milling. With increasing the milling time from 3 to 12 h, the particle size of formed Bi4Ti3O12 did not reduce significantly. The grain size was less than 16 nm and showed a strong tendency to agglomeration. The nucleation and phase formation of Bi4Ti3O12, crystal structure, microstructure, powder grain size and specific surface area were followed by XRD, Rietveld refinement analysis, SEM and the BET specific surface area measurements. Raman spectroscopy was used to explain the structural properties of Bi4Ti3O12 powder, prepared by mechanically assisted synthesis. Reduction in grain size with the increase of milling time was also noted (change in the position and relative intensity), which indicated changes in the structure, caused by nanodimension grains. The sample milled for 12 h and subsequently sintered at 1000?C for 24 h exhibited a hysteresis loop, confirming that the synthesized material possesses ferroelectric properties. .

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A Tem Study of Slip Systems in MoSi2/WSi2 Alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100089020 ◽

1991 ◽

Vol 49 ◽

pp. 942-943

Author(s):

Stuart A. Maloy

Keyword(s):

Solid Solution ◽

Solid Solution Hardening ◽

Slip Systems ◽

High Melting ◽

Group 14 ◽

Solution Hardening ◽

Brittle To Ductile Transition ◽

High Melting Temperature ◽

Tetragonal Unit Cell ◽

Structural Applications

MoSi2 has recently been investigated as a potential material for high temperature structural applications. It has excellent oxidation resistance up to 1700°C, a high melting temperature, 2030°C, and a brittle-to-ductile transition temperature at 900-1000°C. WSi2 is isomorphous with MoSi2 and has a body-centered tetragonal unit cell of the space group 14/mmm. The lattice parameters are a=3.20 Å and c=7.84 Å for MoSi2 and a=3.21 Å and c=7.88 Å for WSi2. Therefore, WSi2 was added to MoSi2 to improve its strength via solid solution hardening. The purpose of this study was to investigate the slip systems in polycrystalline MoSi2/WSi2 alloys.

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Effect of Composition on the Morphology and Hardness of Nanostructured Cu Based Composite and Alloy Powders/Granules Produced by High Energy Mechanical Milling

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.29-30.143 ◽

2007 ◽

Vol 29-30 ◽

pp. 143-146 ◽

Cited By ~ 1

Author(s):

Aamir Mukhtar ◽

De Liang Zhang ◽

C. Kong ◽

P. R. Munroe

Keyword(s):

Grain Size ◽

Mechanical Milling ◽

Alloy Powder ◽

High Energy ◽

Al2o3 Nanoparticles ◽

X Ray ◽

Fine Powders ◽

Average Grain Size ◽

Powder Particles

Cu-(2.5 or 5.0vol.%)Al2O3 nanocomposite balls and granules and Cu-(2.5vol.% or 5.0vol.%)Pb alloy powder were prepared by high energy mechanical milling (HEMM) of mixtures of Cu and either Al2O3 or Pb powders. It was observed that with the increase of the content of Al2O3 nanoparticles from 2.5vol.% to 5vol.% in the powder mixture, the product of HEMM changed from hollow balls into granules and the average grain size and microhardness changed from approximately 130nm and 185HV to 100nm and 224HV, respectively. On the other hand, HEMM of Cu–(2.5 or 5.0vol.%) Pb powder mixtures under the same milling conditions failed to consolidate the powder in-situ. Instead, it led to formation of nanostructured fine powders with an average grain size of less than 50nm. Energy dispersive X-ray mapping showed homogenous distribution of Pb in the powder particles in Cu–5vol.%Pb alloy powder produced after 12 hours of milling. With the increase of the Pb content from 2.5 to 5.0 vol.%, the average microhardness of the Cu-Pb alloy powder particles increases from 270 to 285 HV. The mechanisms of the effects are briefly discussed.

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