Browsing by Author "Mahmoud, M. A."

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    Effect of torsional oscillations on the stress-strain behavior of Al-5 wt% Mg alloy
    (ELSEVIER SCIENCE SA, 2011) Mahmoud, M. A.; El-Rehim, A. F. Abd; Sobhy, M.; Rahman, R. M. Abdel
    The microstructure and mechanical properties of a precipitation hardenable Al-5 wt% Mg alloy subjected to low frequency torsional oscillations and aging treatments are reported in the present work. The stress-strain response was examined at different frequencies (1.53-3.3 Hz) and at constant shear strain amplitude ((phi = 5.69 x 10(-4)). An excessive in the softening was observed by increasing both frequency of the applied oscillations and deformation temperature. The change in the hardening and softening parameters of stress-strain relations was explained in view of spinodal decomposition in Al-Mg systems. The mean value of activation energy was found to be equal to that quoted for precipitate-dislocation intersection. (C) 2011 Elsevier B.V. All rights reserved.
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    The variation of work hardening characteristics of Al-5 wt% Mg alloy during phase transition
    (ELSEVIER, 2010) Mahmoud, M. A.; Sobhy, M.; Abd El-Rehim, A. F.; Rahman, R. M. Abdel
    The aim of this study is to investigate the effect of aging conditions on the stress-strain behavior along with microstructure changes of the Al-5 wt% Mg alloy. Following solid solution treatment and aging of specimens at temperatures ranging from 373 to 573 K for various aging times (1/4 to 4 h), stress-strain tests were performed at different testing temperatures (313-343 K). The work hardening parameters (sigma(y), sigma(f), chi(p), and Y) were found to decrease continuously with pre-aging times at all aging and testing temperatures, where the softening parameters (epsilon(f) and L) oppose this behavior. The variation in stress-strain parameters with increasing aging temperatures and aging times was explained on the basis of structural transformations taking place in the Al-Mg alloy. A precipitate-dislocation intersections mechanism was assumed as the rate-controlling mechanism for alloy. (C) 2010 Elsevier B.V. All rights reserved.