Study of Precipitation Hardening in Two Al-Mg-Si Alloys with and without Copper and Excess Silicon Using Kissinger and Boswell Methods

2019 ◽  
Vol 397 ◽  
pp. 101-110
Author(s):  
Fares Serradj ◽  
Hichem Farh ◽  
Brahim Belfarhi
Keyword(s):  
Isoconversional Methods ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Electron Microscopic ◽  
X Ray ◽  
Excess Silicon ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Dsc Curves

The precipitation of two 6xxx (Al-Mg-Si) alloys with and without copper (Cu) and excess silicon (Si) has been investigated by using the differential scanning calorimetry (DSC), transmission electron microscopic (TEM) and X ray diffraction (XRD) analysis. The analysis of the DSC curves found that the excess Si accelerate the precipitation. The values of activation energies for each peak of DSC curves were determined by using Kissinger–Akahira–Sunose (KAS) and Boswell isoconversional methods. The alloy which has an excess Si and copper require larger activation energy for precipitation despite the acceleration of the precipitation by the excess Si. TEM observation result shows there is smaller size and higher density of precipitate in excess Si alloy than those of excess-free.

Synthesis of nanometer-sized particles of barium orthotitanate prepared through a modified reverse micellar route: Structural characterization, phase stability and dielectric properties

2004 ◽  
Vol 19 (10) ◽  
pp. 2905-2912 ◽  
Author(s):  
Tokeer Ahmad ◽  
Ashok K. Ganguli
Keyword(s):  
Martensitic Transition ◽  
Line Broadening ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Microscopic Studies ◽  
Size Of Particles ◽  
Reverse Micellar

Nanoparticles of barium orthotitanate (Ba2TiO4) was obtained using microemulsions (avoiding Ba-alkoxide). Powder x-ray diffraction studies of the powder after calcining at 800 °C resulted in a mixture of orthorhombic (70%) and monoclinic (30%) phases. The high-temperature orthorhombic form present at 800 °C was due to the small size of particles obtained by the reverse micellar route. Pure orthorhombic Ba2TiO4 was obtained on further sintering at 1000 °C with lattice parameters a = 6.101(2) Å, b =22.94(1) Å, c = 10.533(2) Å (space group, P21nb). The particle size obtained from x-ray line broadening studies and transmission electron microscopic studies was found to be 40–50 nm for the powder obtained after heating at 800 °C. Sintering at 1000 °C showed increase in grain size up to 150 nm. Our studies corroborate well with the presence of a martensitic transition in Ba2TiO4. The dielectric constant was found to be 40 for Ba2TiO4 (at 100 kHz) for samples sintered at 1000 °C. The dielectric loss obtained was low (0.06) at 100 kHz.

scholarly journals Synthesis, Characterization, and Photocatalytic Performance of Mesoporous α-Mn2O3 Microspheres Prepared via a Precipitation Route

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Manoj Pudukudy ◽  
Zahira Yaakob
Keyword(s):  
Electron Microscopy ◽  
Uv Light ◽  
Thermal Transformation ◽  
Xrd Analysis ◽  
Structural Deformation ◽  
Blue Dye ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Transmission Electron

α-Mn2O3 microspheres with high phase purity, crystallinity, and surface area were synthesized by the thermal decomposition of precipitated MnCO3 microspheres without the use of any structure directing agents and tedious reaction conditions. The prepared Mn2O3 microspheres were characterized by Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) and photoluminescence (PL) studies. The complete thermal transformation of MnCO3 to Mn2O3 was clearly shown by the FTIR and XRD analysis. The electron microscopic images clearly confirmed the microsphere-like morphology of the products with some structural deformation for the calcined Mn2O3 sample. The mesoporous texture generated from the interaggregation of subnanoparticles in the microstructures is visibly evident from the TEM and BET studies. Moreover, the Mn2O3 microstructures showed a moderate photocatalytic activity for the degradation of methylene blue dye pollutant under UV light irradiation, using air as the potential oxidizing agent.

Bicontinuous Cubic Phase as a Matrix for the Synthesis of Semiconductor Nanocrystallites

1996 ◽  
Vol 431 ◽  
Author(s):  
Jianping Yang ◽  
Syed Qadri ◽  
Banahalli Ratna
Keyword(s):  
Size Distribution ◽  
Cubic Phase ◽  
Lipid Matrix ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Bicontinuous Cubic ◽  
First Time

AbstractBicontinuous cubic phase of lipid has been utilized for the first time as a matrix to synthesize II–VI (CdS) and IV–VI (PbS) semiconductor nanocrystallites. The nanoparticles were isolated from the lipid matrix and stabilized by capping with a thiol compound before purification. Two different sizes (2.3 nm and 3.0 nm) of CdS particles were prepared by varying the conditions of preparation. The size was determined by a combination of UV-vis absorption spectra and X-ray diffraction (XRD). The steep absorption edges of the two CdS samples indicate very narrow size distribution. XRD and transmission electron microscopic imaging of PbS nanocrystallites revealed that the size was 4.9 nm with nearly monodispersed size distribution.

High Temperature MOVPE Growth of AlxGa1−xN (0.2-1) Layers on Sapphire and SiC Substrates for the Fabrication Deep UV Optical Devices

2006 ◽  
Vol 955 ◽  
Author(s):  
Balakrishnan Krishnan ◽  
Masataka Imura ◽  
Kazuyoshi Iida ◽  
Kentaro Nagamatsu ◽  
Hiroki Sugimura ◽  
...  
Keyword(s):  
High Temperature ◽  
Microscopic Analysis ◽  
Dislocation Loops ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Transmission Electron Microscopic ◽  
Transmission Electron Microscopic Analysis

ABSTRACTSingle crystalline AlN epitaxial layers have been grown on and (0001) sapphire and 6H-SiC substrates by MOVPE technique at high temperatures in the range of 1340-1500°C. The structural qualities of the high temperature grown AlN layers were found to be good as evidenced by X-ray diffraction analyses results. By transmission electron microscopic analysis, dislocation densities of the layers were found to be 6.2 × 107 cm−2 or lower and the formation of dislocation loops was confirmed. High temperature bridge layers of AlN and AlxGa1−xN layers were grown on linear-groove patterned sapphire based AlN templates and 6H-SiC substrates. AlxGa1−xN bridge layers exhibited different growth behaviours depending on the direction of groove patterns on the sub-strates.

scholarly journals Crystallization of Fe-Based Bulk Amorphous Alloys

2015 ◽  
Vol 60 (1) ◽  
pp. 7-10 ◽  
Author(s):  
K. Błoch ◽  
M. Nabiałek ◽  
M. Dośpiał ◽  
S. Garus
Keyword(s):  
Amorphous Alloys ◽  
Rapid Quenching ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Two Stages ◽  
Two Peaks ◽  
Structure Investigations ◽  
Dsc Curves

Abstract The aim of this paper is to present the results of crystallization studies for the bulk amorphous (Fe0.61Co0.10Zr0.025Hf0.025 Ti0.02W0.02B0.20)98Y2, Fe61Co10TixY6B20, Fe61Co10Ti2Y7B20 alloys. The crystallization of the alloys was studied by differential scanning calorimetry (DSC). The amorphicity of the investigated alloys in the as-quenched state was testified using Mossbauer spectroscopy, X-ray diffractometry and transmission electron microscopy. Moreover, X-ray diffractometry was applied to structure investigations of partially crystallized samples. The crystallization process in the investigated alloys occurs in one or two stages. Two peaks in the DSC curves can be overlapped or well separated indicating the complex crystallization processes. From X-ray diffraction we have stated that in both types of devitrification the crystalline phase can be ascribed to the α-FeCo. In the first stage the crystalline grains seem to grow from the nuclei frozen in the samples during the rapid quenching, whereas in the second one both the growth of the existed grains and creation of new ones during annealing may occur.

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