Papers by Author: M. Draissia

Abstract: Rapidly solidified Al-Zn alloys with Zn contents ranging up to 50 wt.% were made under vacuum, by high-frequency (HF) induction melting, from compacted mixture targets of Al and Zn of fine (99.99 % purity) elemental powders. The microstructural characteristics and strengthening mechanisms were investigated. The crystallographic microstructures were characterized by means of X-ray diffraction (XRD) analyses and optical microscopy observations as well as Vickers microhardness testing. Detailed overviews of alloying solubility of zinc in aluminium were given. Extensive solid solutions of CFC Al were found in the (HF) Al-Zn alloys, and a higher Vickers microhardnesses compared to that of pure (HF) aluminium.

Abstract: In this article, the liquid-solid interface solidification stability of dilute binary alloy systems during unidirectional (z) solidification was investigated. A new quantitative approach is proposed with (z-δ) as a variable to solve the equation of solute diffusion in the liquid, where δ is the real diffusion layer thickness.

Abstract: X-ray tools are being powerful methods for qualitative and quantitative analyses of nanocrystalline materials This work is an overview of detailed X-ray investigations relative to microstructural studies applied for a refined binary Al-based alloys thin films system as samples deposited on glass substrates. Energy dispersive analysis of X-ray (EDAX), X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods were used to determine the chemical composition, the microstructure parameters and the solubility of copper in aluminum.

Abstract: The instrumented indentation technique is being widely used for the determination of elasto-plastic properties of metallic materials by analyzing located atomic force microscopy (AFM) image area and loading-displacement data of indentation imprints after testing. This data analysis is highly dependent on the method followed for interpretation the loading and unloading curves. We have detailed the two common methods, the Oliver&Pharr method based on a power law and the energetic approach method based on finite elements, in order of understanding the nano-indentation unloading behavior to determine the closer hardness and Young’s modulus of metallic materials..

Abstract: The thermomechanical treatment at 1050°C under a stress of about 30 MPa, of milled ribbons from Fe-25Cr-20Ni (0.060%Ni-0.1%Ti) refractory stainless steel, leads to a recrystallisation of the as-melt-spun structure which is intermediate between cellular and columnar dendritic. The mean grain size in the relatively high density zones (85%) may be considered as low and do not exceed 10µm. Other grains appear abnormally large and reach 30µm. The origin of these grains, must be researched in an exaggerate growth phenomenon under a local deformation near the critical work hardening.