TAIBI KAMEL - Academia.edu (original) (raw)

Papers by TAIBI KAMEL

AIP Conference Proceedings, 2010

ABSTRACT The Ni-Al-Ta ternary alloys in the Ni-rich part present complex microstructures. They ar... more ABSTRACT The Ni-Al-Ta ternary alloys in the Ni-rich part present complex microstructures. They are composed of multiple phases that are formed according to the nominal composition of the alloy, primary Ni(gamma), Ni3Al(gamma'), Ni6AlTa(tau3), Ni3Ta(delta) or in equilibrium: two solid phases (gamma'-tau3), (tau3-delta), (tau3-gamma), (gamma-delta) or three solid phases (gamma'-tau3-delta). The nature and the volume fraction of these phases give these alloys very interesting properties at high temperature, and this makes them attractive for specific applications. We have developed a series of ternary alloys in electric arc furnace, determining their solidification sequences using Differential Thermal Analysis (DTA), characterized by SEM-EDS, X-ray diffraction and by a microhardness tests. The follow-up results made it possible to make a correlation between the nature of the formed phases and their solidifying way into the Ni75AlxTay (x+y = 25at.%) system, which are varied and complex. In addition to the solid solution Ni (gamma), the formed intermetallics compounds (gamma', tau3 and delta) has been identified and correlated with a complex balance between phases.We noticed that the hardness increases with the tantalum which has a hardening effect and though the compound Ni3Ta (delta) is the hardest. The below results provide a better understanding of the complex microstructure of these alloys.

Matériaux & Techniques, 2011

Le present travail consiste en une etude comparative du procede de combustion auto-propagee (SHS ... more Le present travail consiste en une etude comparative du procede de combustion auto-propagee (SHS : self-propagating high temperature synthesis) applique aux systemes Ti-C, Ti-Al-C et Fe-Al. Il apparait que la reaction, enclenchee par chauffage local, est plus rapide dans le cas du Ti-C ou la forte exothermicite se manifeste par une sorte d’explosion contrairement au systeme Fe-Al ou le front de reaction se deplace dans l’echantillon sous forme de « flamme solide ». L’interet de l’activation mecanique associee au procede SHS apparait notamment dans les cas Ti-C et Ti-Al-C contrairement au Fe-Al ou la reaction s’enclenche seulement par simple chauffage. La synthese du carbure de titane TiC et du carbure mixte de titane et d’aluminium Ti4 Al2 C2 a ete realisee par SHS a partir de melanges pulverulents (Ti-C ou Ti-Al-C) prealablement actives. Pour le systeme Fe-Al, la reaction s’enclenche et se deplace dans une pastille obtenue par compression uniaxiale d’un melange de poudres non broyees et produit le compose intermetallique FeAl. Dans ce cas, l’influence de la morphologie et de la granulometrie des particules de fer a ete abordee en etudiant le gonflement engendre par la reaction et les produits synthetises.

Intermetallics, 2013

ABSTRACT Detailed electrochemical analysis in moderate corrosive environment and the microstructu... more ABSTRACT Detailed electrochemical analysis in moderate corrosive environment and the microstructures examination have been conducted for different iron-aluminide Fe-28% Al alloys prepared from Cr, Nb and Zr additions. The electrochemical corrosion tests performed in a low chlorinated medium (Na2SO4 0.05 mol L−1 + NaCl 0.5 g L−1) showed an increasing protective effect against corrosion attack for 2% and 5% Cr and for 0.5% and 2% Nb alloys. In contrast addition of 0.5% and 2% Zr to Fe-28% Al leads to a generalized corrosion phenomenon, which decreases after the addition of Cr and Nb. The examination by a dispersive energy spectrometer in scanning electron microscope of corroded samples reveals the origin of pits initiation, which are developed around Fe2AlCr, Fe3Nb(Al), Fe2(AlZr) phases and are also present around Fe3AlC0.69,Cr23C6, NbC, and ZrC carbide precipitates. It is noted that these carbides are formed at the grain boundaries and inside grain of Fe3Al matrix. Details microstructural study of these phases were confirmed by X-ray diffraction analysis and present the driving main cause of the embrittlement and pitting corrosion of these alloys.

Ceramics International, 2014

ABSTRACT Nickel-copper ferrites with the general formula Ni1-xCuxFe2O4 (0 <= x <= 1... more ABSTRACT Nickel-copper ferrites with the general formula Ni1-xCuxFe2O4 (0 <= x <= 1) were studied using X-ray diffraction and infrared absorption spectroscopy. XRD diffraction patterns show that all samples have a pure single-phase cubic spinel structure over the whole composition range. From these patterns, the lattice parameters, crystallite size and porosity of these samples have been calculated and compared with those predicted theoretically. Most of the values were found to increase with increasing Cu content. Far infrared absorption spectra show high and low absorption bands corresponding to tetrahedral and octahedral sites confirming the single phase spinnel structure. The calculated force constants, K-t, and K-o for the two sites are found to increase with increasing Cu content and their relative values are consistent with bond length magnitudes at tetrahedral and octahedral sites. Crown Copyright

Powder Technology, 2011

This work focuses on the synthesis of FeAl intermetallic compound by combustion synthesis (SHS pr... more This work focuses on the synthesis of FeAl intermetallic compound by combustion synthesis (SHS process) and its inclusion as dispersoids in a copper matrix to develop a metal matrix composite (MMC) by sintering. In the first step, FeAl compound was produced by the sintering of Fe–50 at.%Al at 1100 °C. Then, after grinding and mixing with copper powder, it was sintered in solid phase and liquid phase to obtain a metal matrix composite. The Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM and EDS-X) analysis showed that copper diffuses in the microporosity of the FeAl particles and leaves porosity in the matrix. FeAl was milled by high energy to reduce the size of particles. It was then co-milled with copper to coat its particles in order to achieve higher density. The results showed that copper coats the FeAl particles which become finer and less porous. However, a low porosity persists in the matrix after sintering.A copper matrix composite reinforced with FeAl particles, synthesized by combustion synthesis, was developed by sintering. It was noted that copper diffuses in the FeAl microporosity and generates porosity in the matrix. The high energy ball milling of FeAl powder reduces size of particles and micro-porosity, this leads to higher bulk density.

Applied Mathematical Modelling, 2011

This paper presents a 3D geometric modelling of a twin helical spring and its finite element anal... more This paper presents a 3D geometric modelling of a twin helical spring and its finite element analysis to study the spring mechanical behaviour under tensile axial loading. The spiralled shape graphic design is achieved through the use of Computer Aided Design (CAD) tools, of which a finite element model is generated. Thus, a 3D 18-dof pentaedric elements are employed to discretise the complex “wired-shape” of the spring, allowing the analysis of the mechanical response of the twin spiralled helical spring under an axial load. The study provides a clear match between the evolution of the theoretical and the numerical tensile and compression normal stresses, being of sinusoidal behaviour. The overall equivalent stress isovalues increases radially from 0° to 180°, being maximal on the internal radial zone at the section 180°. On the other hand, the minimum stress level is located in the centre of the filament cross section.

Journal of Solid State Electrochemistry, 2010

... steel in a simulated solution at different temperatures and immersion times Yamina Louafi &am... more ... steel in a simulated solution at different temperatures and immersion times Yamina Louafi &Mohamed Arezki Ladjouzi & Kamel Taibi Received: 22 July 2009 /Revised: 27 October 2009 /Accepted: 28 October 2009 /Published online: 11 December 2009 © Springer-Verlag 2009 ...

Journal of Non-crystalline Solids, 2007

Cu70Fe18Co12 alloy is prepared by mechanical alloying of pure Cu, Fe, Co powder using a high ener... more Cu70Fe18Co12 alloy is prepared by mechanical alloying of pure Cu, Fe, Co powder using a high energy ball mill, with increasing milling time ranging from 4 to 8, 24, 36 and 54 h. The variation of the morphology and the elemental distribution were measured at these different stages on various grains of the alloy using a scanning electron microscope with a dispersive energy analyzer. Atomic clusters of iron were observed on some grains after 8 h of milling, confirming the non-homogenisation of the powder at this stage. Beyond 12 h, the homogenisation is ensured over a volume of one cube micron. Microstructural changes during the mechanical alloying have been studied by X-ray diffractometry (XRD) and Mössbauer spectroscopy. X-ray diffraction measurements confirm the dissolution of iron and cobalt phases in the FCC matrix of copper after 24 h of milling with increase of the structural parameter. This same dissolution was also measured by Mössbauer spectroscopy, confirming that after 4 h of milling the CuFe phase begins to form and iron dissolution is incomplete with partial amount of alpha Fe phase surviving after 36 h of milling.