Papers by Author: S.A. Aly

Abstract: The electrical resistivity and the corresponding mechanical properties (hardness) of some 5xxx Al-Mg alloy processed by plastic deformation were investigated. Plastic deformation was performed at room temperature. Isothermal annealing produced a significant change in both the electrical and mechanical properties of the samples. As the annealing time was increased, the resistivity and hardness up to full recovery. The activation enthalpy of migration of defects was determined, was found to be 0.234±0.06 eV, 0.218±0.049 eV, 0.316±0.016 eV 0.232±0.012 eV for 5005, 5251, 5052 and 5754 alloys, respectively.

Abstract: Electrical techniques have been used to study the thermal vacancies in 401.0 casting aluminum alloy. Quenching experiments were usually performed on thin specimens to ensure a uniform quenching rate throughout the specimen. After grinding, polishing and etching, samples of 401.0 were homogenized for 12h at 673K and annealed for 90min., before quenched in water (277K) and then subjected to electrical measurements. From such measurements it is possible to deduce the vacancy formation enthalpy, which in combination with the results of self-diffusion measurements, give a value for the migration enthalpy of the vacancy.

Abstract: A Vanadium Pentoxide Sample with a Film Thickness of 75 Nm Has Been Thermally Evaporated on Unheated Glass Substrate Using V₂O₅ High Purity Powder. the Sample Was Subjected to a Subsequent Post-Deposition Annealing in Air at Different Temperatures for a Period of One Hour. the Optical Properties Were Studied by Transmittance and Reflectance Measurements. the Integrated Visible ,T_Vis, and Solar, T_Sol, Transmittance Were Calculated. the Spectral Behaviour of the Refractive Index as Well as the Absorption Coefficient before and after Post-Deposition Heat-Treatment Was Also Reported. X-Ray Diffraction Confirmed that the Film in the as-Deposited as Well as after Annealing up to 400 °C Is in the Amorphous State.

Abstract: The optical properties of cobalt oxide samples prepared by spray pyrolysis technique on glass substrates with different film thicknesses have been studied. The structural characteristics of the samples were investigated using X-ray diffraction. The optical properties of the prepared films were studied by transmittance and reflectance measurements, and the integrated transmittance (TVIS, and TNIR) and absorptance (AVIS and ANIR) in VIS and NIR regions was calculated and found to be affected by film thickness. The dependence of absorption coefficient on wave length was also reported. The energy gap was calculated and two energies have been observed at 2.15 and 1.5 eV suggesting that the deposited films are semi-conducting with allowed direct transitions.

Abstract: The optical properties of tungsten oxide (WO3) films prepared by DC sputtering on unheated glass substrates with different film thicknesses have been studied. The structural characteristics of the samples were investigated using X-ray diffraction. The optical properties of the prepared films were studied by transmittance and reflectance measurements, and the integrated transmittance (TUV, TVIS, and TNIR) and absorption (AUV, AVIS, and ANIR) in UV, VIS and NIR regions. The integrated UV absorption and transmittance are varied with the film thicknesses, also, no remarkable change in VIS and NIR regions was observed. The dependence of refractive index as well as extinction coefficient on wavelength was also reported. The energy gap was calculated and is located around 3.25 eV.