Papers by Author: Ali Mostaed

Abstract: In this work, the preparation of nanostructured Al-4.5wt%Mg powder through the mechanical alloying (MA) process was evaluated. The X-ray diffraction (XRD) technique was used to calculate the crystallite size and microstrain. Scanning electron microscopy (SEM) was used not only to study the morphology of the powders but also to show the fact that the Mg powders were distributed during the MA process. Transmission electron microscopy (TEM) was also used to demonstrate whether the produced powders are nanostructured or not. XRD results showed that microstrain and crystallite size of milled powder (after 10 h milling at the ball-to-powder weight ratio (BPR) of 20:1) were ≈-0.34% and ≈20nm respectively. XRD and TEM results showed that Al₁₂Mg₁₇ has been formed during MA process. This means that during this process, mutual diffusion of Al and Mg has occurred.

Abstract: Fabrication of alloys in the solid state via mechanical alloying (MA) process has been studied by earlier researchers. The effects of milling time and impact force, defined as the ball-to-powder weight ratio (BPR), on the elemental diffusion during synthesis of nanostructured Fe-50at.%Cu alloy via MA process were evaluated in the current work. X-ray diffraction patterns revealed that increasing the milling time and impact force give rise to increasing the micro-strain, lattice parameter and decreasing the crystallite size during the MA process. Furthermore, scanning electron microscopy (SEM) was utilized not only for evaluating the microstructure of the milled powder particles but also for proving this claim that during MA process, the mutual diffusion of Cu and Fe has occurred. The interpretation of data resulted have been discussed in details.

Abstract: The effects of volume fraction at different milling times and impact forces, defined as the ball-to-powder weight ratio (BPR), on the elemental diffusion during mechanical alloying process of Al-4.5wt%Cu/SiC composite were evaluated and compared with the SiC free samples (Al-4.5wt%Cu alloy) in the current work. X-ray diffraction patterns of the monolithic and composite samples imply the fact that a higher level of mutual diffusion of constituents, Al and Cu, happened in the matrix in the presence of SiC particles. This effect of the reinforcing particles can be attributed to the increased densities of dislocation and vacancy caused by the presence of SiC particles within the matrix giving rise to increasing the micro-strain, lattice parameter and decreasing the crystallite size.

Abstract: The study of mechanical alloying (MA) process on the immiscible Al–Cu systems having positive heats of mixing has been investigated by the earlier researchers. However, a comprehensive understanding of the diffusion phenomenon during the mechanical alloying process is still far from complete. The effects of milling time and impact force, defined as the ball-to-powder weight ratio (BPR), on the elemental diffusion during mechanical alloying process of Al-4.5wt%Cu were evaluated in the current work. X-ray diffraction results showed that increasing the milling time and impact force led to increasing the dislocation as because of increasing the micro-strain, lattice parameter and decreasing the crystallite size. As a result of this, the diffusion rate was enhanced. The interpretation of data resulted have been discussed in details.