EFFECT OF SUBSTRATE THICKNESS ON NANOSTRUCTURE AND MECHANICAL PROPERTIES OF BULK NANOCRYSTALLINE Fe3Al PREPARED BY ALUMINOTHERMIC REACTION

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1572-1577
Author(s):  
PEIQING LA ◽  
LI WANG ◽  
YANG ZHAO ◽  
CHUNJIE CHEN
Keyword(s):  
Grain Size ◽  
Nanocrystalline Phase ◽  
Substrate Thickness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Aluminothermic Reaction ◽  
Transmission Electron ◽  
Bulk Nanocrystalline ◽  
Nanocrystalline Phases ◽  
Different Thickness

Bulk nanocrystalline Fe 3 Al materials were prepared by aluminothermic reaction on the substrates with different thickness of 5~15 mm . Grain size of the materials was measured by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Compressive strength and hardness of the materials were tested. The results showed the materials consisted of amorphous and nanocrystalline phases. With the substrate thickness increasing, amount of the nanocrystalline phase increased and that of the amorphous decreased and grain size of the nanocrystalline increased and a few grains in micrometer appeared in part areas of the materials. Yield strength and hardness of the materials remarkably decreased with the substrate thickness.

Microstructures and Mechanical Properties of Bulk Nanocrystalline Fe3Al Materials With 5, 10 and 15 wt. % Cu Prepared by Aluminothermic Reaction

2011 ◽  
Vol 236-238 ◽  
pp. 2191-2196 ◽  
Author(s):  
Yu Peng Wei ◽  
Pei Qing La ◽  
Mei Dan Que ◽  
Wen Sheng Li ◽  
Yang Yang ◽  
...  
Keyword(s):  
Yield Strength ◽  
Optical Microscope ◽  
Matrix Phase ◽  
Coarse Grained ◽  
Compressive Yield Strength ◽  
Nanocrystalline Phase ◽  
X Ray Diffraction ◽  
Aluminothermic Reaction ◽  
Transmission Electron ◽  
Bulk Nanocrystalline

Bulk nanocrystalline Fe3Al based materials with 5, 10 and 15 wt. % Cu were prepared by aluminothermic reaction in which the melts were superheated about 1600 K before solidification. Microstructures of those materials were investigated by optical microscope, electron probe microanalysis, X-ray diffraction and transmission electron microscope. It was shown that microstructures of the materials consisted of a nanocrystalline matrix phase and a little contamination Al2O3and Fe3AlCxfiber phases. The nanocrystalline matrix phase was composed of Fe, Al and Cu elements and disordered bcc which did not change with content of Cu. Average grain sizes of the nanocrystalline phase of the materials with 5, 10 and 15 wt. % Cu were 18, 24 and 25 nm respectively and that of the material with 5 wt. % Cu was the smallest. Compressive properties of the materials were tested. The material with 5 wt. % Cu has good ductility compared with the materials with 10 and 15 wt. % Cu. Yield strength of the materials was about two times higher than that of coarse grained Fe3Al material. The compressive yield strength of the material with 5 wt. % Cu was higher than those of the materials with 10 and 15 wt. % Cu and its flow stress in compression was up to about 1500 MPa.

Effect of Nitridation Magnetic Properties of Nanocrystalline Fe-Co Alloy Powders

2010 ◽  
Vol 654-656 ◽  
pp. 1106-1109
Author(s):  
Ya Qiong He ◽  
Chang Hui Mao ◽  
Jian Yang
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Alloy Powder ◽  
High Energy ◽  
X Ray Diffraction ◽  
Powder Mixtures ◽  
X Ray ◽  
Transmission Electron ◽  
Nitridation Temperature ◽  
Microstructure And Magnetic Properties

Nanocrystalline Fe-Co alloy powders, which were prepared by high-energy mechanical milling, were nitrided under the mixing gas of NH3/H2 in the temperature range from 380°C to 510°C. X-ray diffraction (XRD) was used to analyze the grain size and reaction during the processing. The magnetic properties of the nitrided powders were measured by Vibrating Sample Magnetometer (VSM). The results show that with the appearance of Fe4N phase after nitride treatment, and the grain-size of FeCo phase decreases with the increase of nitridation temperature between 380°C to 450°C.The saturation magnetization of nitrided alloy powder treated at 480°C is about 18% higher than that of the initial Fe-Co alloy powder, accompanied by the reduction of the coercivity. Transmission electron microscope (TEM) was used, attempting to further analyze the effect of Fe4N phase on microstructure and magnetic properties of the powder mixtures.

TEM Study of FePt and FePt:C/FePt Composite Double-Layered Thin Films

2013 ◽  
Vol 275-277 ◽  
pp. 1952-1955
Author(s):  
Ling Fang Jin ◽  
Xing Zhong Li
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Magnetic Properties ◽  
Composite Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

New functional nanocomposite FePt:C thin films with FePt underlayers were synthesized by noneptaxial growth. The effect of the FePt layer on the ordering, orientation and magnetic properties of the composite layer has been investigated by adjusting FePt underlayer thickness from 2 nm to 14 nm. Transmission electron microscopy (TEM), together with x-ray diffraction (XRD), has been used to check the growth of the double-layered films and to study the microstructure, including the grain size, shape, orientation and distribution. XRD scans reveal that the orientation of the films was dependent on FePt underlayer thickness. In this paper, the TEM studies of both single-layered nonepitaxially grown FePt and FePt:C composite L10 phase and double-layered deposition FePt:C/FePt are presented.

EFFECT OF NANOCRYSTALLIZATION ANNEALING ON MAGNETIC PROPERTIES AND MAGNETOIMPEDANCE OF CO-BASE RIBBONS

2012 ◽  
Vol 05 ◽  
pp. 841-846
Author(s):  
AMIR KEYVANARA ◽  
REZA GHOLAMIPOUR ◽  
SHAMSEDIN MIRDAMADI ◽  
FARZAD SHAHRI ◽  
HOSSEIN SEPEHRI AMIN
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Magnetic Properties ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Melt Spun ◽  
Melt Spun Ribbons ◽  
Nanocrystalline Phases

Melt spun ribbons of Co 64 Fe 4 Ni 2 B 19 Si 8 Cr 3 alloy have been prepared and the nanocrystallization process was carried out by the heat treatment of the as spun ribbons above the crystallization temperature. Structural studies of the samples have been performed by transmission electron microscopy and X-ray diffraction. Magnetic properties of the samples and magnetoimpedance measurements were investigated and it was revealed that magnetic properties and magnetoimpedance of the samples deteriorate by the formation of nanocrystalline phases.

Grain Size Dependent Magnetic Properties of Nanocrystalline Sm [BE]Co [BD][BJ]/Cu

2001 ◽  
Vol 703 ◽  
Author(s):  
L. Bessais ◽  
C. Djéga-Mariadassou ◽  
J. Zhang ◽  
V. Lalanne ◽  
A. Percheron-Guégan
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Rietveld Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Magnetic Metal ◽  
Chemical Distribution

ABSTRACTThe evolution of both micro structural and magnetic properties of the Sm[BE]Co[BD][BJ] Cu powder, is studied as a function of soft co-milling time. The average grain size in the range 20 - 50 nm was determined by transmission electron microscopy coupled with x-ray diffraction using the Rietveld method. The particle shape and chemical distribution were investigated by elemental mapping, using wavelength dispersive x-ray analysis with electron microprobe analysis. The coercivity evolution shows that an optimum value of 6 kOe is obtained after 5 h co-milling. The microstructure analysis indicates that both materials are well mixed in nanometer scale. This technique appears as a potential route to synthesize nanocrystalline Sm[BE]Co[BD][BJ] isolated by non-magnetic metal Cu.

Nanocrystallization of gas atomized Cu47Ti33Zr11Ni8Si1 metallic glass

2006 ◽  
Vol 21 (3) ◽  
pp. 597-607 ◽  
Author(s):  
S. Venkataraman ◽  
S. Scudino ◽  
J. Eckert ◽  
T. Gemming ◽  
C. Mickel ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Primary Crystallization ◽  
Nanocrystalline Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
20 Nm ◽  
Annealing Experiments

Cu47Ti33Zr11Ni8Si1 metallic glass powder was prepared by gas atomization. Decomposition in the amorphous alloy and primary crystallization has been studied by differential scanning calorimetry (DSC), x-ray diffraction (XRD), and transmission electron microscopy (TEM). The glassy powder exhibits a broad DSC exotherm prior to bulk crystallization. Controlled annealing experiments reveal that this exotherm corresponds to a combination of structural relaxation and nanocrystallization. A uniform featureless amorphous contrast is observed in the TEM prior to the detection of nanocrystals of 4–6 nm in size. High-resolution TEM studies indicate that this nanocrystalline phase has a close crystallographic relationship with the γ–CuTi phase having a tetragonal structure. The product of the main crystallization event is also nanocrystalline, hexagonal Cu51Zr14, having dimensions of 20 nm. However, there is no evidence for possible amorphous phase separation prior to the nanocrystallization events.

Reaction Layer Microstructure of SiC/SiC Joints Brazed by Ag-Cu-Ti Filler Metal

2010 ◽  
Vol 434-435 ◽  
pp. 202-204 ◽  
Author(s):  
Yan Liu ◽  
Zheng Ren Huang ◽  
Xiu Jian Liu
Keyword(s):  
Grain Size ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Reaction Layer ◽  
Filler Metal ◽  
Growth Behavior ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electronic Probe

Abstract. The reaction layer microstructure of SiC/SiC joints brazed by Ag-Cu-Ti filler metal, including composition, morphology, grain size were investigated by X-ray diffraction, electronic probe microanalysis, transmission electron microscope. An obvious reaction layer composed of TiC and Ti5Si3 was observed at the interface of SiC substrate and filler metal. There is a representative structure of SiC substrate/continuous fine TiC layer /discontinuous coarse Ti5Si3 layer/filler metal in the reaction layer. The continuous TiC layer, composed of about 10 nm roundish grains, is 350 ~ 400 nm thick. Ti5Si3 layer is composed of only one row of Ti5Si3 grains, which disperse with diverse size from 100 ~ 500 nm. Different growth behavior of TiC and Ti5Si3 is the main reason to form this microstructure.

Heat Treatment of Nanocrystalline Al2O3-Zr02

1996 ◽  
Vol 457 ◽  
Author(s):  
Bridget M. Smyser ◽  
Jane F. Connelly ◽  
Richard D. Sisson ◽  
Virgil Provenzano
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Grain Size ◽  
Monoclinic Phase ◽  
Phase Distribution ◽  
Critical Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated

ABSTRACTThe effects of grain size on the phase transformations in nanocrystalline ZrO2-Al2O3 have been experimentally investigated. Compositions from 10 to 50 vol% Al2O3 in ZrO2 were obtained as a hydroxide gel. The powders were then calcined at 600 °C for 17 hours and heat treated at 1100 °C for 24 and 120 hours and at 1200 °C for 2 hours. The phase distribution and grain size were determined using x-ray diffraction and transmission electron microscopy. The initial grain size after calcining was 8–17 nm. It was determined that the critical ZrO2 grain size to avoid the tetragonal to monoclinic phase transformation on cooling from 1100 °C was between 17 and 25 nm. Samples containing 50% Al2O3 maintained a grain size below the critical size for all times and temperatures. The 30% Al2O3 samples showed the same behavior in all but one heat treatment. The remainder of the samples showed significant grain growth and at least partial transformation to the monoclinic phase.

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