Browsing by Author "H. Belhouchet"

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    Heat treatment and kinetics of precipitation of β-Mg17Al12 phase in AZ91 alloy
    (Université de M'sila, 2018) M. Fatmi; A. Djemli; A. Ouali; T. Chihi; M.A. Ghebouli; H. Belhouchet
    This study investigated the effect of aging on the precipitation and kinetics of second phase Mg17Al12 in AZ91 magnesium alloy (Mg-9 wt% Al-1 wt% Zn), using X-ray diffraction, microhardness measurements and differential scanning calorimetric analysis (DSC). With the last instrument, the all samples were heated from room temperature to 400 °C, at heating rates of 10–30 °C/min. The results were supplemented by measuring the average of activation energies, using isothermal treatments by Johnson–Mehl–Avrami (JMA) methods and by non-isothermal treatments using Ozawa, Boswell, Kissinger, Mahadevan, Augis and Bennett methods, were around 67.18 and 62.02 kJ/mol. The frequency factor k0 calculated by the isothermal treatment is equal to 1.24 109 s−1. In non-isothermal treatment, the numerical factor m and the Avrami parameter n is estimated to be approximately equal to 3 and 2.79 respectively. This value corresponding that the bulk nucleation with a constant number of nuclei was dominant in three-dimensional (polyhedron) controlled by interface reaction.
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    Sintering behaviour of fluorapatite–silicate composites produced from natural fluorapatite and quartz
    (Université de M'sila, 2021) D. Kherifi; H. Belhouchet; S. Ramesh; K.Y. Sara Lee; A. Kenzour; S. Djoualah; M.K; G. Abbas; Y.H. Wong; S. Ramesh
    In this work, the sintering behaviour of fluorapatite (FAp)–silicate composites prepared by mixing variable amounts of natural quartz (2.5 wt% to 20 wt%) and FAp was studied. The composites were pressureless sintered in air at temperatures from 1000 ◦C to 1350 ◦C. The effects of temperatures on the densification, phase formation, chemical bonding and Vickers hardness of the composites were evaluated. All the samples exhibited mixed phase, comprising FAp and francolite as the major constituents along with some minor phases of cristobalite, wollastonite, dicalcium silicate and/or whitlockite dependent on the quartz content and sintering temperature. The composite containing 2.5 wt% quartz exhibited the best sintering properties. The highest bulk density of 3 g/cm3 and a Vickers hardness of >4.2 GPa were obtained for the 2.5 wt% quartz–FAp composite when sintered at 1100 ◦C. The addition of quartz was found to alter the microstructure of the composites, where it exhibited a rod-like morphology when sintered at 1000 ◦C and a regular rounded grain structure when sintered at 1350 ◦C. A wetted grain surface was observed for composites containing high quartz content and was believed to be associated with a transient liquid phase sintering