EVALUATION OF NANOCRYSTALLINE BA(ZRXTI1-X)O3 PRODUCED BY MECHANICAL ALLOYING

2012 ◽  
Vol 05 ◽  
pp. 472-479
Author(s):  
M. Hajfathalian ◽  
Z. A. Nemati ◽  
H. R. Madaah Hosseini
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Structural Changes ◽  
Ferroelectric Properties ◽  
High Energy ◽  
Structural Development ◽  
Transition Electron Microscopy ◽  
Nano Crystalline ◽  
High K ◽  
Different Temperatures

BaTiO 3-based solid solutions involve high piezoelectric and ferroelectric properties. One of the most favorable systems of this material is Ba ( Zr x Ti 1- x ) O 3. While nano structured ceramics of which have a great potential for using them in capacitors, actuators, transducers and dielectrics to reach high K values. In this study, nano crystalline Ba ( Zr x Ti 1- x ) O 3( x =0.1-0.8) which is called BZT composite has been prepared by mechanical alloying. The parameters affecting the process and properties were evaluated. The starting powders that are used here were nano sized high pure ZrO 2; submicron sized high pure TiO 2 and BaCO 3. The prepared powder was calcined, compacted and sintered at different temperatures and in various times. The structural changes and phase developments during mechanical alloying were studied by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) and Transition Electron Microscopy (TEM). The results showed that by using mechanical alloying method, high dense nano crystalline BZT ceramics were obtained successfully at very low sintering temperature. The dielectric constant of BZT was much great, because of using nano materials in this method at the temperatures of 1250-1400°C. The effect of high energy milling in micro structural development of nano crystalline BZT has been discussed as well as dielectric properties.

SYNTHESIS OF NANO-CRYSTALLINE Cu-Cr ALLOY BY MECHANICAL ALLOYING

2012 ◽  
Vol 05 ◽  
pp. 496-501 ◽  
Author(s):  
S. SHEIBANI ◽  
S. HESHMATI-MANESH ◽  
A. ATAIE
Keyword(s):  
Mechanical Alloying ◽  
Structural Evolution ◽  
High Energy ◽  
Lattice Parameter ◽  
Control Agent ◽  
Milling Process ◽  
X Ray Diffraction ◽  
Nano Crystalline ◽  
High Energy Ball Mill ◽  
Energy Ball

In this paper, the influence of toluene as the process control agent (PCA) and pre-milling on the extension of solid solubility of 7 wt.% Cr in Cu by mechanical alloying in a high energy ball mill was investigated. The structural evolution and microstructure were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, respectively. The solid solution formation at different conditions was analyzed by copper lattice parameter change during the milling process. It was found that both the presence of PCA and pre-milling of Cr powder lead to faster dissolution of Cr . The mean crystallite size was also calculated and showed to be about 10 nm after 80 hours of milling.

Structural and Chemical Properties of MBE Grown Niobium Overlayers on (110) Rutile

1996 ◽  
Vol 441 ◽  
Author(s):  
J. Marien ◽  
T. Wagner ◽  
M. Rühle
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Defect Structure ◽  
Chemical Properties ◽  
High Energy ◽  
Initial Growth ◽  
High Energy Electron ◽  
Transmission Electron ◽  
Different Temperatures ◽  
And Chemical Properties

AbstractThin Nb films were grown by MBE in a UHV chamber at two different temperatures (50°C and 950°C) on the (110) surface of TiO2 (rutile).At a growth temperature of 50°C, reflection high energy electron diffraction (RHEED) revealed epitaxial growth of Nb on rutile: (110)[001] TiO2 ¦¦ (100)[001] Nb. In addition, investigations with Auger electron spectroscopy (AES) revealed that a chemical reaction took place between the Nb overlayer and the TiO2 substrate at the initial growth stage. A 2 nm thick reaction layer at the Nb/TiO2 interface has been identified by means of conventional transmission electron microscopy (CTEM) and high-resolution transmission electron microscopy (HRTEM).At a substrate temperature of 950°C, during growth, the Nb film was oxidized completely, and NbO2 grew epitaxially on TiO2. The structure and the chemical composition of the overlayers have been investigated by RHEED, AES, CTEM and HRTEM. Furthermore, it was determined that the reaction of Nb with TiO2 is governed by the defect structure of the TiO2 and the relative oxygen affinities of Nb and TiO2.

The Effect of Reinforcement Phase on the Microstructure of Al-SiC Nanocomposite Powder Prepared via Mechanical Alloying

2009 ◽  
Vol 83-86 ◽  
pp. 764-770
Author(s):  
Taha Rostamzadeh ◽  
H. Shahverdi ◽  
R. Sarraf-Mamoory ◽  
A. Shanaghi
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Metal Matrix ◽  
Milling Time ◽  
Lattice Strain ◽  
Volume Fraction ◽  
Aluminum Matrix ◽  
High Energy ◽  
Nanocomposite Powder ◽  
Nanocomposite Powders

Mechanical alloying is one of the most successful methods for the manufacturing of metal matrix nanocomposite powders. In this study, Al/SiC metal matrix composite (MMCp) powders with volume fractions of 5, 10, and 15 percent SiC were successfully obtained after milling the powder for a period of 25 hours at a ball to powder ratio of 15:1 using high energy planetary milling. The Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were conducted to investigate the lattice strain of the matrix phase and the microstructure of the nanocomposite powders after 1, 10, and 25 hours of milling time. Also, the morphology of the Al-5%SiC nanocomposite powder was investigated using transmission electron microscopy (TEM). The results show that with the increase of both milling time and the reinforcement phase volume fraction, the lattice strain increases and the average size of aluminum phase crystallites decreases. Eventually, after 25 hours of milling, the nanocomposite powders show a spherical-like morphology and SiC particles were distributed in an aluminum matrix with appropriate order.

scholarly journals Synthesis of the Mg2Ni Alloy Prepared by Mechanical Alloying Using a High Energy Ball Mill

2019 ◽  
Vol 54 (1) ◽  
Author(s):  
José Luis Iturbe-García ◽  
Manolo Rodrigo García-Núñez ◽  
Beatriz Eugenia López-Muñoz
Keyword(s):  
Mechanical Alloying ◽  
Ball Mill ◽  
Structural Changes ◽  
Weight Ratio ◽  
Structural Evolution ◽  
High Energy ◽  
Process Time ◽  
High Energy Ball Mill ◽  
Energy Ball ◽  
Steel Balls

Mg2Ni was synthesized by a solid state reaction from the constituent elemental powder mixtures via mechanical alloying. The mixture was ball milled for 10 h at room temperature in an argon atmosphere. The high energy ball mill used here was fabricated at ININ. A hardened steel vial and three steel balls of 12.7 mm in diameter were used for milling. The ball to powder weight ratio was 10:1. A small amount of powder was removed at regular intervals to monitor the structural changes. All the steps were performed in a little lucite glove box under argon gas, this glove box was also constructed in our Institute. The structural evolution during milling was characterized by X-ray diffraction and scanning electron microscopy techniques. The hydrogen reaction was carried out in a micro-reactor under controlledconditions of pressure and temperature. The hydrogen storage properties of mechanically milled powders were evaluated by using a TGA system. Although homogeneous refining and alloying take place efficiently by repeated forging, the process time can be reduced to one fiftieth of the time necessary for conventional mechanical milling and attrition.        

Effect of Boron on the Amorphization of Fe-Si Alloys by Mechanical Alloying

2012 ◽  
Vol 730-732 ◽  
pp. 739-744 ◽  
Author(s):  
Petr Urban ◽  
Francisco Gomez Cuevas ◽  
Juan M. Montes ◽  
Jesus Cintas
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Alloy System ◽  
High Energy ◽  
Milling Process ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Structural And Phase Transformations ◽  
Transmission Electron ◽  
Energy Ball

The amorphization process by mechanical alloying in the Fe-Si alloy system has been studied. High energy ball milling has been applied for alloys synthesis. X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to monitor the structural and phase transformations through the different stages of milling. The addition of amorphous boron in the milling process and the increase of the milling time were used to improve the formation of the amorphous phase. Heating the samples resulted in the crystallization of the synthesized amorphous alloys and the appearance of equilibrium intermetallic compounds.

Synthesis of LaCoO3 powder by a combined mechanical/thermal process

2018 ◽  
Vol 73 (10) ◽  
pp. 719-724
Author(s):  
Vittorio Berbenni ◽  
Chiara Milanese ◽  
Giovanna Bruni ◽  
Alessandro Girella
Keyword(s):  
Electron Microscopy ◽  
Thermal Process ◽  
Electrode Materials ◽  
Gas Sensing ◽  
High Energy ◽  
Combined Use ◽  
Synthetic Procedure ◽  
Different Temperatures ◽  
Physical Mixing ◽  
Scanning Electron

AbstractLanthanum cobaltite, LaCoO3, finds applications as an oxidation and reduction catalyst in gas-sensing materials and in electrode materials for high-temperature fuel cells. The compound has been synthesized through several routes aimed at obtaining LaCoO3 at lower temperatures. We propose a synthetic procedure based on the combined use of mechanical and thermal energy on mixtures of Co(II) oxalate dehydrate and La acetate sesquihydrate. We studied the reactions taking place by increasing the temperature. The study has been performed either on mixtures prepared by a simple physical mixing of the reactants or on the same mixtures after having been subjected to mechanical activation by high-energy milling. The products formed in the mixtures by annealing at different temperatures have been characterized by means of different experimental techniques (thermogravimetric analysis, XRPD, IR, scanning electron microscopy).

In Situ Fabrication and Characterization of (NiCr)Al-Al2O3 Nanocomposite by Mechanical Alloying

2012 ◽  
Vol 16 ◽  
pp. 21-27 ◽  
Author(s):  
Amir Reza Shirani-Bidabadi ◽  
Ali Shokuhfar ◽  
Mohammad Hossein Enayati ◽  
Mazda Biglari
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Structural Changes ◽  
Formation Mechanisms ◽  
Cross Sectional ◽  
Molar Ratios ◽  
Transmission Electron ◽  
Powder Particles

In this research, the formation mechanisms of a (NiCr)Al-Al2O3 nanocomposite were investigated. The structural changes of powder particles during mechanical alloying were studied by X-ray difractometry (XRD) and the morphology and cross sectional microstructure of powder particles were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The methodology involved mechanical alloying of NiO, Cr, and Al with molar ratios of 3:3:8. During mechanical alloying, NiO was first quickly reduced by aluminum atoms to produce NiAl nanocrystalline and Al2O3. Subsequently, and when a longer milling time was applied, chromium atoms diffused into the NiAl lattice. The heat treatment of this structure led to the formation of the (NiCr)Al intermetallic compound as well as Al2O3 with crystalline sizes of 23 nm and 58 nm, respectively.

Synthesis of Nanocrystalline Fe25Al57.5Ni17.5 by Mechanical Alloying

2012 ◽  
Vol 476-478 ◽  
pp. 1318-1321
Author(s):  
Qi Zhi Cao ◽  
Jing Zhang
Keyword(s):  
Thermal Analysis ◽  
Solid Solution ◽  
Differential Thermal Analysis ◽  
Mechanical Alloying ◽  
Ball Mill ◽  
Structural Changes ◽  
Early Stage ◽  
High Energy ◽  
X Ray Diffraction ◽  
X Ray

Nanostructured Fe25Al57.5Ni17.5intermetallics was prepared directly by mechanical alloying (MA) in a high-energy planetary ball-mill. The phase transformations and structural changes occurring in the studied material during mechanical alloying were investigated by X-ray diffraction (XRD). Thermal behavior of the milled powders was examined by differential thermal analysis (DTA). Disordered Al(Fe,Ni) solid solution was formed at the early stage. After 50 h of milling, Al(Fe,Ni) solid solution transformed into Al3Ni2，AlFe3，AlFe0.23Ni0.77 phase. The power annealed at temperature 500 results in forming of intermetallics AlFe3 and FeNi3 after 5h milling. The nanocrystalline intermetallic compound was obtained after 500h milling.

Nanotubes Obtained from Mono and Bimetallic Carbides Produced by Mechanical Alloying

2007 ◽  
Vol 539-543 ◽  
pp. 2731-2736
Author(s):  
Lucia Díaz-Barriga Arceo ◽  
L. Rendón-Vázquez ◽  
Eligio Orozco ◽  
V. Garibay-Febles ◽  
E. Palacios Gonzalez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Mechanical Alloying ◽  
High Energy ◽  
Step Method ◽  
Heat Treated ◽  
Microstructural Characterisation

The main purpose of this work was to produce nanotubes using a two step method: mechanical alloying and heat treatment. Mechanical Alloying (MA) was used to prepare the monometallic Co3C carnide and the bimetallic C-25%at Ni-25%at Mo carbide with Ti impuririties by milling of pure elemental powders of cobalt, molibdenum, titanium and carbon, in a high-energy rotatory mill under an Ar atmosphere. The nanocrystalline carbides were used to produce metal filled nanotubes and nanoparticles, by means of precipitation after heating for 15 minutes at 800°C. Microstructural characterisation of the as-milled and heat-treated powders was performed using Transmisssion Electron Microscopy (TEM) techniques. It was possible to obtain filled nanotubes, carbide nanorods, and observe a nucleation phenomena inside carbon cavities.

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