Characterization of the Consolidation Behavior of Fabricated Nanocrystalline-Nanopowders of TiC/Al-2124 Composite

2006 ◽  
Author(s):  
Hanadi G. Salem ◽  
Sherif El Eskandarany ◽  
Hassan Abdul Fattah
Keyword(s):  
Internal Structure ◽  
Applied Pressure ◽  
Processing Parameters ◽  
High Energy ◽  
Nanocrystalline Powders ◽  
X Ray Diffraction ◽  
Major Interest ◽  
The Matrix ◽  
Average Size ◽  
Consolidation Behavior

Nanoscale materials have been the subject of major interest in recent years due to the anticipated ultrahigh strength and toughness combination anticipated in contrast to materials with conventional meso and micro-scale structures. The key issue lays in the optimization of the processing parameters suitable for the production of bulk nanostructured materials (BNSM) with superior properties suitable for elevated and cryogenic temperature applications. In the current research, a top down approach was employed for the refinement of a micron scale Al-2124 alloy powder about 45μm in average size using high energy ball milling up to 24 hours. Reinforcement of the refined Al-2124 nanocrystalline powders with 1μm nanostructured powder of TiC with internal structure <100 nm was performed to investigate the compaction and consolidation behavior of the produced nanocomposites. X-ray diffraction was employed to determine the crystallite size as a function of milling time (MT). microhardness of the milled powders was characterized for the hot compacts. Microstructural evolution of the green compacts was investigated by a 1nm resolution field emission scanning electron microscope (SEM), while the hot compacts were investigated using optical microscopy. Nanocrystalline-nanopowders <300nm in particle size and 20nm internal structural size were fabricated successfully at 24hr of MT from a 45μm particle sized 2124-Al powder with internal structure of 78nm in average size. The green compact densities of the nanoscale powder decreased to 92% compared to 97% for the microscale as-received powder due to the resistance of the strain hardened agglomerates to the applied pressure used for compaction. The microscale as-received powder was severely deformed during compaction, which resulted in higher densities. The degree by which the density decreased with the addition of 5-wt% TiC to the matrix was much lower for the nanoscale powder compared to the microscale one due to the low RPS ratio between the matrix and the reinforcement which promoted uniform distribution of the TiC particles within the matrix agglomerates. Increasing TiC content up to 10 wt% resulted in the formation of large voids and cavities. Refinement of the microscale powder to the nanoscale size resulted in 22.5% increase in hardness in the un-reinforced condition. Moreover, significant increase in hardness was also achieved with increasing TiC-content up to 10%.

scholarly journals Multiscale Copper-µDiamond Nanostructured Composites

2012 ◽  
Vol 730-732 ◽  
pp. 925-930
Author(s):  
Daniela Nunes ◽  
Vanessa Livramento ◽  
Horácio Fernandes ◽  
Carlos Silva ◽  
Nobumitsu Shohoji ◽  
...  
Keyword(s):  
Pure Copper ◽  
Thermal Stabilization ◽  
Hot Extrusion ◽  
Processing Parameters ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Optimal Processing ◽  
Novel Approach ◽  
Transmission Electron

Nanostructured copper-diamond composites can be tailored for thermal management applications at high temperature. A novel approach based on multiscale diamond dispersions is proposed for the production of this type of materials: a Cu-nDiamond composite produced by high-energy milling is used as a nanostructured matrix for further dispersion of micrometer sized diamond. The former offers strength and microstructural thermal stability while the latter provides high thermal conductivity. A series of Cu-nDiamond mixtures have been milled to define the minimum nanodiamond fraction suitable for matrix refinement and thermal stabilization. A refined matrix with homogenously dispersed nanoparticles could be obtained with 4 at.% nanodiamond for posterior mixture with mDiamond and subsequent consolidation. In order to define optimal processing parameters, consolidation by hot extrusion has been carried out for a Cu-nDiamond composite and, in parallel, for a mixture of pure copper and mDiamond. The materials produced were characterized by X-ray diffraction, scanning and transmission electron microscopy and microhardness measurements.

Appropriate Conditions for Preparation of Nanosized WO3 through High-Energy-Milling

2011 ◽  
Vol 194-196 ◽  
pp. 665-668
Author(s):  
Chun Huan Chen ◽  
Rui Ming Ren
Keyword(s):  
Grain Size ◽  
Milling Time ◽  
Rotation Speed ◽  
Processing Parameters ◽  
High Energy ◽  
Charge Ratio ◽  
Activation Process ◽  
X Ray Diffraction ◽  
High Energy Milling ◽  
Transmission Electron

In order to synthesize WC-Co nanopowders through an integrated mechanical and thermal activation process, WO3-Co2O3-C nanopowders need to be obtained first. It is critical how to obtain the WO3-Co2O3-C nanopowders efficiently. The effect of processing parameters on the grain size during high-energy-milling of WO3-Co2O3-C mixed powders was studied via X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the grain size of reactants can be effectively decreased with increasing the milling time, rotation speed, and charge ratio. After a certain time milling, both WO3 and C powders achieve nano-level in grain size and mixed homogeneously. The appropriate milling parameters for fabricating nanosized WO3+C+Co2O3 powders are suggested to be 4 to 8 hours of milling time, 400 RPM of rotation speed, and 40:1 to 60:1 of charge ratio.

Effect of Milling Speed on the Synthesis of In-Situ Cu-25 Vol. % WC Nanocomposite by Mechanical Alloying

2012 ◽  
Vol 59 (2) ◽  
Author(s):  
Nurulhuda Bashirom ◽  
Nurzatil Ismah Mohd Arif
Keyword(s):  
Stainless Steel ◽  
Mechanical Alloying ◽  
Weight Ratio ◽  
High Energy ◽  
Milling Process ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
The Matrix ◽  
Steel Balls

This paper presents a study on the effect of milling speed on the synthesis of Cu-WC nanocomposites by mechanical alloying (MA). The Cu-WC nanocomposite with nominal composition of 25 vol.% of WC was produced in-situ via MA from elemental powders of copper (Cu), tungsten (W), and graphite (C). These powders were milled in the high-energy “Pulverisette 6” planetary ball mill according to composition Cu-34.90 wt% W-2.28 wt% C. The powders were milled in different milling speed; 400 rpm, 500 rpm, and 600 rpm. The milling process was conducted under argon atmosphere by using a stainless steel vial and 10 mm diameter of stainless steel balls, with ball-to-powder weight ratio (BPR) 10:1. The as-milled powders were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). XRD result showed the formation of W2C phase after milling for 400 rpm and as the speed increased, the peak was broadened. No WC phase was detected after milling. Increasing the milling speed resulted in smaller crystallite size of Cu and proven to be in nanosized. Based on SEM result, higher milling speed leads to the refinement of hard W particles in the Cu matrix. Up to the 600 rpm, the unreacted W particles still existed in the matrix showing 20 hours milling time was not sufficient to completely dissolve the W.

Obtaining of the Ir-Al Nanocrystalline Powders by Mechanical Alloying

2011 ◽  
Vol 672 ◽  
pp. 171-174
Author(s):  
Ionel Chicinaş ◽  
P. Cârlan ◽  
Florin Popa ◽  
Virgiliu Călin Prică ◽  
Lidia Adriana Sorcoi
Keyword(s):  
Mechanical Alloying ◽  
Particle Morphology ◽  
High Energy ◽  
Atomic Ratio ◽  
Planetary Mill ◽  
Nanocrystalline Powders ◽  
Alloy Formation ◽  
X Ray Diffraction ◽  
Chemical Homogeneity ◽  
Diffraction Patterns

The Ir-Al powder in the 1:1 atomic ratio was obtained by high energy mechanical alloying in a Pulverisette 4 Fritch planetary mill. The final product was obtained after 28 h of milling in argon atmosphere. Alloy formation was investigated by X-ray diffraction. After 4 h of milling the new structure of IrAl compound is found in the diffraction patterns. The obtained powders are nanocrystalline with a mean crystallite size of 11 nm after 28 h of milling. The particle morphology and the chemical homogeneity were studied using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDX). It was found that the obtained compound present large particles composed by smaller one.

Nanocomposite Bi(Sb)Te(Se) Materials by Cryogenic Mechanical Alloying and Optimized High Pressure Hot-pressing

2012 ◽  
Vol 1456 ◽  
Author(s):  
Tsung-ta E. Chan ◽  
Rama Venkatasubramanian ◽  
James M. LeBeau ◽  
Peter Thomas ◽  
Judy Stuart ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Hot Pressing ◽  
High Energy ◽  
Structural Features ◽  
Milling Process ◽  
Nanocrystalline Powders ◽  
Full Density ◽  
Seebeck Coefficients ◽  
The Matrix ◽  
Cryogenic Process

ABSTRACTNanocomposite Bi2Te3 based alloys are attractive for their potentially high thermoelectric figure-of-merit (ZT) around room temperature. The nano-scale structural features embedded in the matrix provide more scattering of phonons and can thus reduce the lattice thermal conductivity. To further take advantage of such nanocomposite structures, we focus on the development of nanocrystalline Bi(Sb)Te(Se) powders by high energy cryogenic mechanical alloying followed by an optimized hot pressing process. This approach is shown to successfully produce Bi(Sb)Te(Se) alloy powders with grain size averaging about 9 nm for n-type BiTe(Se) and about 16 nm for p-type Bi(Sb)Te respectively. This cryogenic process offers much less milling time and prevents thermally activated contamination or imperfections from being introduced during the milling process. The nanocrystalline powders are then compacted at optimized pressures and temperatures to achieve full density compactions and preserve the grain sizes effectively. The resulting nano-bulk materials have optimal Seebeck coefficients and are expected to have improved ZT. Thermoelectric properties and microstructure studies by X-ray diffraction and transmission electron microscopy will also be presented and discussed.

Synthesis and Characterization of CeO2 Nanoparticles

2016 ◽  
Vol 683 ◽  
pp. 281-287 ◽  
Author(s):  
Ivan N. Lapin ◽  
Anastasiia V. Shabalina ◽  
Valery Svetlichnyi
Keyword(s):  
Cerium Oxide ◽  
Ethanol Solution ◽  
Nanocrystalline Powders ◽  
X Ray Diffraction ◽  
Active Components ◽  
X Ray ◽  
Average Size ◽  
First Time ◽  
Metallic Target

Dispersions of cerium oxide nanoparticles in water, ethanol, and water-ethanol solution were synthesized for the first time using laser ablation of metallic target. The fundamental harmonic of nanosecond Nd:YAG laser was used. Nanocrystalline powders of cerium oxide were obtained from the dispersions. The average size of the crystallites was 17-19 nm. Phase composition of nanoparticles was confirmed by X-ray diffraction and Raman spectroscopy. It was found that carbon present on the surface of CeO2 particles. The materials obtained may be used as catalyst carriers for CO oxidation, and as active components of sunscreen cosmetic products.

In Situ Structural Evolution of Steel-Based MMC by High Energy X-Ray Diffraction and Comparison with Micromechanical Approach

2013 ◽  
Vol 768-769 ◽  
pp. 313-320 ◽  
Author(s):  
Guillaume Geandier ◽  
Moukrane Dehmas ◽  
Mickael Mourot ◽  
Elisabeth Aeby-Gautier ◽  
Sabine Denis ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Coefficient Of Thermal Expansion ◽  
Hydrostatic Stress ◽  
Structural Evolution ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
The Matrix

In situ high energy X-ray diffraction synchrotron was used to provide direct analysis of the transformation sequences in steel-based matrix composite (MMC) reinforced with TiC particles. Evolution of the phase fractions of the matrix and TiC particles as well as the mean cell parameters of each phase were determined by Rietveld refinement from high energy X-ray diffraction (ID15B, ESRF, Grenoble, France). In addition, some peaks were further analysed in order to obtain the X-ray strain during the cooling step. Non-linear strain evolutions of each phase are evidenced, which are either associated with differences in the coefficient of thermal expansion (CTE) between matrix and TiC particle or to the occurrence of phase transformation. Micromechanical calculations were performed through the finite element method to estimate the stress state in each phase and outline the effects of differences in CTE and of volume change associated with the matrix phase transformation. The calculated results led to a final compressive hydrostatic stress in the TiC reinforcement and tensile hydrostatic stress in the matrix area around the TiC particles. Besides, the tendencies measured from in situ synchrotron diffraction (mean cell parameters) matched with the numerical estimates.

Synthesis and Characterization of Sn Doped SiO2 by Reverse Micelle and Sol-Gel Process

2012 ◽  
Vol 724 ◽  
pp. 225-228
Author(s):  
Kwang Jin Jeong ◽  
Dong Sik Bae
Keyword(s):  
Reverse Micelle ◽  
Sol Gel ◽  
Processing Parameters ◽  
Metal Alkoxide ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Hydrolysis And Condensation ◽  
Micro Emulsion ◽  
Average Size

Sn doped SiO2nanoparticles have been synthesized using a reverse micelle technique combined with metal alkoxide hydrolysis and condensation. The size of the particles and the thickness of the coating can be controlled by manipulating the relative rates of the hydrolysis and condensation reactions of tetraethyl orthosilicate (TEOS) within the micro-emulsion. The properties of the Sn doped SiO2nanoparticles were studied as a function of various processing parameters such as R and H value. The average size of synthesized Sn doped SiO2nanoparticles was about in the size range of 20-40 nm and core particle (Sn) 1-5 nm. The Sn doped SiO2nanoparticles were characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM).

Recovering Nano-Sized SnO2 from Electronic Wastes by Ultrasonic-Assisted Electrochemical Method

2012 ◽  
Vol 550-553 ◽  
pp. 2024-2028
Author(s):  
Jian Jun Shi ◽  
Sheng Wang ◽  
Ting Ting He ◽  
Dao Yuan Zhou
Keyword(s):  
Electrochemical Method ◽  
Room Temperature ◽  
Tin Dioxide ◽  
High Energy ◽  
X Ray Diffraction ◽  
Environment Friendly ◽  
X Ray ◽  
Ultrasonic Assisted ◽  
One Step ◽  
Average Size

Tin dioxide nanoparticles were directly one-step recovered from electronic wastes using ultrasonic-assisted electrochemical method. The products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), which indicated that the average size of tetragonal SnO2 is 100 nm. The experiment parameters, such as the concentration of electrolyte, electrolysis current, reaction time and electrode distance, were also discussed. The proposed method is high energy efficient, non-toxic and environment-friendly, and suitable for the recovering of electronic wastes under the controllable reaction condition at room temperature.

scholarly journals Bulk Behavior of Ball Milled AA2124 Nanostructured Powders Reinforced with TiC

2009 ◽  
Vol 2009 ◽  
pp. 1-12 ◽  
Author(s):  
Hanadi G. Salem ◽  
Sherif El-Eskandarany ◽  
Amr Kandil ◽  
Hassan Abdul Fattah
Keyword(s):  
Compressive Strength ◽  
Internal Structure ◽  
Research Work ◽  
High Energy ◽  
Reinforced Composite ◽  
Peak Aging ◽  
Energy Ball ◽  
Average Size ◽  
20 Nm ◽  
Bulk Behavior

In the current research work, a top-down approach was employed for the refinement of a micron scale AA2124 alloy powder 40 μm in average size using high-energy ball milling up to 60 hours. The produced nanopowders were investigated compared to the micron gas atomized powder both in the monolithic and the reinforced composite states. 1 μm powder of TiC with internal structure <100 nm was used for the reinforcement of the 2124-Al matrices. Milling time of 36 hours produced a <100 nm nanopowders with internal structure size <20 nm. The nanopowder monolithic consolidates exhibited compressive strength of 388 MPa compared to 313 MPa for micronpowder one. Addition of TiC nanostructured powder to the nanopowder consolidated matrix resulted in increase of 130% in compressive strength compared to that produced for the microscale one. Nanopowder of Alalloys produced by mechanical milling reinforced with 10 wt% TiC is recommended for products suitable for high wear and erosion resistance applications. Peak aging increased the hardness and compressive strength of the as compacted micronpowder matrices by an average of 188% and 123%, while increased that of the nanopowder matrices by an average of 110% and 117%, respectively.

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